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Acinetobacter baumannii causes severe infections in humans, resists multiple antibiotics, and survives in stressful environmental conditions due to modulations of its complex transcriptional regulatory network (TRN). Unfortunately, our global understanding of the TRN in this emerging opportunistic pathogen is limited. Here, we apply independent component analysis, an unsupervised machine learning method, to a compendium of 139 RNA-seq data sets of three multidrug-resistant A. baumannii international clonal complex I strains (AB5075, AYE, and AB0057). This analysis allows us to define 49 independently modulated gene sets, which we call iModulons. Analysis of the identified A. baumannii iModulons reveals validating parallels to previously defined biological operons/regulons and provides a framework for defining unknown regulons. By utilizing the iModulons, we uncover potential mechanisms for a RpoS-independent general stress response, define global stress-virulence trade-offs, and identify conditions that may induce plasmid-borne multidrug resistance. The iModulons provide a model of the TRN that emphasizes the importance of transcriptional regulation of virulence phenotypes in A. baumannii. Furthermore, they suggest the possibility of future interventions to guide gene expression toward diminished pathogenic potential.IMPORTANCEThe rise in hospital outbreaks of multidrug-resistant Acinetobacter baumannii infections underscores the urgent need for alternatives to traditional broad-spectrum antibiotic therapies. The success of A. baumannii as a significant nosocomial pathogen is largely attributed to its ability to resist antibiotics and survive environmental stressors. However, there is limited literature available on the global, complex regulatory circuitry that shapes these phenotypes. Computational tools that can assist in the elucidation of A. baumanniis transcriptional regulatory network architecture can provide much-needed context for a comprehensive understanding of pathogenesis and virulence, as well as for the development of targeted therapies that modulate these pathways.

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii (CRAb) is 1 of the most problematic antimicrobial-resistant bacteria. We sought to elucidate the international epidemiology and clinical impact of CRAb. METHODS: In a prospective observational cohort study, 842 hospitalized patients with a clinical CRAb culture were enrolled at 46 hospitals in five global regions between 2017 and 2019. The primary outcome was all-cause mortality at 30 days from the index culture. The strains underwent whole-genome analysis. RESULTS: Of 842 cases, 536 (64%) represented infection. By 30 days, 128 (24%) of the infected patients died, ranging from 1 (6%) of 18 in Australia-Singapore to 54 (25%) of 216 in the United States and 24 (49%) of 49 in South-Central America, whereas 42 (14%) of non-infected patients died. Bacteremia was associated with a higher risk of death compared with other types of infection (40 [42%] of 96 vs 88 [20%] of 440). In a multivariable logistic regression analysis, bloodstream infection and higher age-adjusted Charlson comorbidity index were independently associated with 30-day mortality. Clonal group 2 (CG2) strains predominated except in South-Central America, ranging from 216 (59%) of 369 in the United States to 282 (97%) of 291 in China. Acquired carbapenemase genes were carried by 769 (91%) of the 842 isolates. CG2 strains were significantly associated with higher levels of meropenem resistance, yet non-CG2 cases were over-represented among the deaths compared with CG2 cases. CONCLUSIONS: CRAb infection types and clinical outcomes differed significantly across regions. Although CG2 strains remained predominant, non-CG2 strains were associated with higher mortality. Clinical Trials Registration. NCT03646227.

With the increase in carbapenem-resistant A. baumannii (CRAB) infections, there has been a resurgence in the use of polymyxins, specifically colistin (COL). Since the reintroduction of COL-based regimens in treating CRAB infections, several COL-resistant A. baumannii isolates have been identified, with the mechanism of resistance heavily linked with the loss of the lipopolysaccharide (LPS) layer of the bacterial outer membrane through mutations in lpxACD genes or the pmrCAB operon. SPR206, a novel polymyxin derivative, has exhibited robust activity against multidrug-resistant (MDR) A. baumannii. However, there is a dearth of knowledge regarding its efficacy in comparison with other A. baumannii-active therapeutics and whether traditional polymyxin (COL) mediators of A. baumannii resistance also translate to reduced SPR206 activity. Here, we conducted susceptibility testing using broth microdilution on 30 A. baumannii isolates (17 COL-resistant and 27 CRAB), selected 14 COL-resistant isolates for genomic sequencing analysis, and performed time-kill analyses on four COL-resistant isolates. In susceptibility testing, SPR206 demonstrated a lower range of minimum inhibitory concentrations (MICs) compared with COL, with a four-fold difference observed in MIC50 values. Mutations in lpxACD and/or pmrA and pmrB genes were detected in each of the 14 COL-resistant isolates; however, SPR206 maintained MICs ≤ 2 mg/L for 9/14 (64%) of the isolates. Finally, SPR206-based combination regimens exhibited increased synergistic and bactericidal activity compared with COL-based combination regimens irrespective of the multiple resistance genes detected. The results of this study highlight the potential utility of SPR206 in the treatment of COL-resistant A. baumannii infections.

Acinetobacter baumannii, a top‐priority WHO pathogen, causes life‐threatening infections in immunocompromised patients, leading to prolonged hospitalisation and high mortality. Here, we used the Galleria mellonella model to investigate community strain C98 (Ab‐C98) virulence via transcriptomic analysis. Ab‐C98 showed greater killing and faster colonisation in larvae than the clinical reference strain (ATCC BAA1605). Genes in three iron clusters, acinetobactin, baumannoferrin and the Feo system, were significantly up‐regulated. Targeted knockout of siderophore genes (basC, bfnD, and the gene encoding isochorismatase) significantly increased the survival of infected larvae by at least 35.16%, identifying these genes as potential targets for developing anti‐virulence agents against A. baumannii. [ABSTRACT FROM AUTHOR]

Carbapenem resistance among bacteria, especially Klebsiella pneumoniae and Acinetobacter baumannii, constitutes a dreadful threat to public health all over the world that requires developing new medications urgently. Carbapenem resistance emerges as a serious problem as this class is used as a last-line option to clear the multidrug-resistant bacteria. Arthrospira maxima (Spirulina) is a well-known cyanobacterium used as a food supplement as it is rich in protein, essential minerals and vitamins and previous studies showed it may have some antimicrobial activity against different organisms. Biosynthesized (green) zinc oxide nanoparticles have been investigated by several researchers as antibacterials because of their safety in health. In this article, previous studies were analyzed to get to a conclusion about their activity as antibacterials. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemical biosensor was developed for the sensitive and selective detection of the Acinetobacter baumannii gene sequence. The biosensor was created by immobilizing a capture probe specific to the A. baumannii gene on the surface of chitosan-gold modified pencil graphite electrodes. Following solid-state hybridization on the Chit-Au/PGE surface, the target DNA sequence of the A. baumannii was detected by measuring the guanine signal using square wave voltammetry (SWV). All experimental parameters impacting sensor response are examined in order to improve hybridization efficacy, and the electrochemical biosensor's performance. The limit of detection (LOD) for the A. baumannii gene sequence was calculated and found to be 1.93 nM. Three different non-complementary DNA sequences were used to evaluate the assay selectivity, but no interference effect was obtained. Additionally, the potential applicability of the biosensor to real samples was tested in artificial serum media. The suggested electrochemical test procedure is simple, approachable, and quick, making it a convenient approach for the screening of DNA sequence. [Display omitted] • Pencil graphite electrodes were modified with chitosan-Au composite. • CHIT-Au/PGEs were used for electrochemical biosensing of A. baumannii gene • The [Fe(CN) 6 ]3-/4- oxidation signal was measured by SWV technique. • The proposed electrochemical assay is simple, rapid, and accessible. [ABSTRACT FROM AUTHOR]

Multidrug-resistant (MDR) Acinetobacter baumannii are of major concern worldwide due to their resistance to last resort carbapenem and polymyxin antibiotics. To develop an effective treatment strategy, it is critical to better understand how an A. baumannii MDR bacterium interacts with its mammalian host. Pattern-recognition receptors sense microbes, and activate the inflammasome pathway, leading to pro-inflammatory cytokine production and programmed cell death. Here, we examined the effects of a systemic MDR A. baumannii infection and found that MDR A. baumannii activate the NLRP3 inflammasome complex predominantly via the non-canonical caspase-11-dependent pathway. We show that caspase-1 and caspase-11-deficient mice are protected from a virulent MDR A. baumannii strain by maintaining a balance between protective and deleterious inflammation. Caspase-11-deficient mice also compromise between effector cell recruitment, phagocytosis, and programmed cell death in the lung during infection. Importantly, we found that cytosolic immunity - mediated by guanylate-binding protein 1 (GBP1) and type I interferon signalling - orchestrates caspase-11-dependent inflammasome activation. Together, our results suggest that non-canonical inflammasome activation via the (Interferon) IFN pathway plays a critical role in the host response against MDR A. baumannii infection. Genetic and Immunological analysis reveal that non-canonical inflammasome activation via type I Interferon pathway plays a critical role in the host response against a multidrug-resistant Acinetobacter baumannii infection in mice. [ABSTRACT FROM AUTHOR]

Introduction: Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia due to impaired insulin production or utilization, leading to severe health complications. Diabetic foot ulcers (DFUs) represent a major complication, often exacerbated by polymicrobial infections involving Staphylococcus aureus and Acinetobacter baumannii. These pathogens, notorious for their resistance to antibiotics, complicate treatment efforts, especially due to biofilm formation, which enhances bacterial survival and resistance. This study explores the synergistic effects of combining gentamicin, imipenem, and fucoidan, a sulfated polysaccharide with antimicrobial properties, against both planktonic and biofilm forms of S. aureus and A. baumannii. Methods: Isolates of S. aureus and A. baumannii were collected from DFUs and genetically confirmed. Methicillin resistance in S. aureus was identified through disk diffusion and PCR. Biofilm formation, including dual-species biofilms, was analyzed using the microtiter plate method. The antimicrobial efficacy of gentamicin, imipenem, and fucoidan was assessed by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC). Synergistic interactions were evaluated using the fractional inhibitory concentration index (FICi) and fractional bactericidal concentration index (FBCi). The expression of biofilm-associated genes (icaA in S. aureus and bap in A. baumannii) was analyzed, and the cytotoxicity of fucoidan was assessed. Results: The study revealed that 77.4% of S. aureus and all A. baumannii isolates showed multidrug resistance. Among 837 tested conditions for dual-species biofilm formation, 72 resulted in strong biofilm formation and 67 in moderate biofilm formation. The geometric mean MIC values for gentamicin were 12.2 µg/mL for S. aureus, 22.62 µg/mL for A. baumannii, and 5.87 µg/mL for their co-culture; for imipenem, they were 19.84, 9.18, and 3.70 µg/mL, respectively, and for fucoidan, 48.50, 31.20, and 19.65 µg/mL, respectively. The MBC values for gentamicin were 119.42, 128, and 11.75 µg/mL; for imipenem, they were 48.50, 14.92, and 8 µg/mL; and for fucoidan, they were 88.37, 62.62, and 42.48 µg/mL. The MBIC values were 55.71, 119.42, and 18.66 µg/mL for gentamicin; 68.59, 48.50, and 25.39 µg/mL for imipenem; and 153.89, 101.49, and 53.53 µg/mL for fucoidan. The MBEC values were 315.17, 362.03, and 59.25 µg/mL for gentamicin; 207.93, 157.58, and 74.65 µg/mL for imipenem; and 353.55, 189.46, and 99.19 µg/mL for fucoidan. When cultured in planktonic form, the geometric mean FICi and FBCi values indicated additive effects, while co-culture showed FICi values of ≤ 0.5, suggesting a synergistic interaction. Treatment with gentamicin and fucoidan led to significant downregulation of the icaA and bap genes in both single-species and dual-species biofilms of S. aureus and A. baumannii. The reductions in gene expression were more pronounced in dual-species biofilms compared to single-species biofilms. Additionally, treatment with imipenem and fucoidan also resulted in significant downregulation of these genes in both biofilm types. Cytotoxicity assessments indicated that higher concentrations of fucoidan were toxic, yet no harmful effects were noted at the optimal synergistic concentrations used with antibiotics. Conclusion: In our investigation, we found that combining gentamicin, imipenem, and fucoidan had a synergistic effect on dual-species biofilms of S. aureus and A. baumannii, suggesting potential benefits for treating such infections effectively. This underscores the importance of understanding microbial interactions, antibiotic susceptibility, and biofilm formation in DFUs. [ABSTRACT FROM AUTHOR]

Hospital surfaces are known to contribute to the spread of healthcare-associated antimicrobial pathogens. Environmental sampling can help locate reservoirs and determine intervention strategies, although sampling and detection can be labor intensive. Composite approaches may help reduce time and costs associated with sampling and detection. We investigated optimum surface areas for sampling antimicrobial-resistant organisms (AROs) with a single side of cellulose sponge, created theoretical composites (TC) by adding recovery results from multiple optimum areas, then compared the TC to the standard Centers for Disease Control and Prevention sampling method (one sponge using all sides, whole tool; (WT)). Five AROs were evaluated: carbapenemase-producing KPC+ Klebsiella pneumoniae (KPC), Acinetobacter baumannii (AB), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecalis (VRE) and Clostridioides difficile spores (CD). Steel coupons comprising four surface areas (323; 645; 1,290 and 2,258 cm2) were inoculated, dried, and sampled with one sampling pass using the larger side (face) or the smaller side (edge) of a pre-moistened cellulose sponge tool. Based on the optimum areas determined for each organism, composite areas were 1,290 cm2 for MRSA and VRE, 1,936 cm2 for AB, 2,580 cm2 for CD spores and 3,870 cm2 for KPC. Total colony forming units (CFU) recovered using a composite approach was greater or comparable than using multiple WT samplings (over the same area as the composite) for MRSA, VRE and AB (130%; 144% and 95%) yet less than if using multiple WT samplings for KP and CD (47% and 66%). We propose a conservative composite sampling strategy if the target organism is unknown; 323 cm2 sampling area for each of the four sides of the sponge, (1290 cm2 total). The conservative composite sampling strategy improved the recovery of KP (from 47% to 85% of multiple WT samplings), while MRSA, VRE, AB and CD (131%; 144%; 97% and 66%) remained within 5% to that of the optimum area TC. [ABSTRACT FROM AUTHOR]

This untargeted metabolomics study investigated the synergistic antibacterial activity of polymyxin B and Leu10-teixobactin, a depsipeptide inhibitor of cell wall biosynthesis. Checkerboard microdilution assays revealed a significant synergy against polymyxin-susceptible and -resistant A. baumannii, excluding lipopolysaccharide-deficient variants. Time-kill assays confirmed bactericidal synergy, reducing bacterial burden by approximately 4-6-log10CFU/mL. The combination (2xMIC polymyxin B and 0.5xMIC Leu10-teixobactin) prevented bacterial regrowth after 24 h, indicating sustained efficacy against the emergence of resistant mutants. The analysis of A. baumannii ATCC™ 19606 metabolome demonstrated that the polymyxin B–Leu10-teixobactin combination produced more pronounced perturbation compared to the individual antibiotics across all time points (1, 3 and 6 h). Pathway analysis revealed that lipid metabolism, cell envelope biogenesis, and cellular respiration were predominantly impacted by the combination, and to a lesser extent by polymyxin B monotherapy. Leu10-teixobactin treatment alone had only a minor impact on the metabolome, primarily at the 6 h time point. Peptidoglycan assays confirmed the combination's concerted deleterious effects on bacterial cell envelope integrity. Electron microscopy further substantiated these findings, revealing pronounced cell envelope damage, membrane blebbing, and vacuole formation. These findings highlight the potential of the polymyxin B–Leu10-teixobactin combination as an effective treatment in preventing resistance in A. baumannii. [ABSTRACT FROM AUTHOR]

Background : Acinetobacter baumannii (AB) is a notable cause of hospital-acquired infections, with carbapenem-resistant Acinetobacter baumannii (CRAB) classified as a high-priority critical pathogen. Bacteriophage therapy is emerging as a promising alternative to combat drug-resistant bacterial infections. In this study, a lytic phage, HZY2308, was isolated from hospital sewage, and the biological properties, biosafety and anti-biofilm properties of phage HZY2308 were characterized and identified. Moreover, the antibacterial effect of phage HZY2308 in combination with antibiotics was investigated, and the apparent characteristics of phage-resistant strain AB48-R were demonstrated, which provided data support for further studies to elucidate the mechanism of generating phage resistance. Methods: Phage HZY2308 was isolated by double agar plate method using clinical strain AB48 as the host bacterium. The morphology of phage HZY2308 was identified by transmission electron microscopy (TEM), and biological characteristics of phage HZY2308 were identified by host range, the efficiency of plating (EOP), sensitivity to temperature, pH, and chloroform, one-step growth curve, the optimal multiplicity of infection (MOI), and detection of endotoxin and cytotoxicity. Besides, the complete genome map of HZY2308 was constructed using CGview, and the phylogenetic tree of HZY2308 was constructed with MEGA. Additionally, the full genomic sequence of phage HZY2308 and the selected phage were compared using Easyfig. Checkerboard test of phage HZY2308 in combination with tigecycline (TGC) was performed to investigate their synergistic effect and bactericidal kinetics. The effect of HZY2308 on biofilm was investigated by semi-quantitative staining of biofilm with crystal violet, determination of bacterial activity in biofilm by 2,3-Bis (2-methoxy-4-nitro-5-sulfophenyl) -2 H-tetrazolium-5-carboxanilide (XTT) assay and observation of biofilm structure by fluorescence microscopy. Finally, Phage-resistant bacteria AB48-R were characterized by colony-forming capacity, morphology, growth curves, adsorption efficiency, and antibiotic susceptibility assays. Results: A lytic phage, HZY2308, was isolated from hospital sewage, which exhibited advantageous traits such as a brief incubation period, large burst size, and robust stability. Safety assessments conducted at both genetic and cellular levels also have yielded positive outcomes. Besides, phage HZY2308 effectively inhibited AB biofilm formation and disrupted established biofilm structures. Furthermore, a synergistic antibacterial effect was noted when phage HZY2308 was combined with tigecycline. Interestingly, the phage-resistant strain, AB48-R was screened through natural selection. Compared to the wild strain AB48, the adsorption efficiency of the phage to AB48-R diminished. However, AB48-R's sensitivity to antibiotics such as cefepime, gentamicin, amikacin, and tobramycin increased, indicating an evolutionary trade-off. Conclusions: Phage HZY2308 shows strong antimicrobial potential, especially in combination with tigecycline, and the phage-resistant strain exhibits increased antibiotic sensitivity. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated BamA, the central component of the β-barrel assembly machinery (BAM), as an important therapeutic target to combat infections caused by Acinetobacter baumannii and other Gram-negative pathogens. Homology modeling indicates BamA in A. baumannii consists of five polypeptide transport-associated (POTRA) domains and a β-barrel membrane domain. We characterized the POTRA domains of BamA from A. baumannii in solution using size-exclusion chromatography small angle X-ray scattering (SEC-SAXS) analysis and determined crystal structures in two conformational states that are drastically different than those previously observed in BamA from other bacteria, indicating that the POTRA domains are even more conformationally dynamic than has been observed previously. Molecular dynamics simulations of the POTRA domains from A. baumannii and Escherichia coli allowed us to identify key structural features that contribute to the observed novel states. Together, these studies expand on our current understanding of the conformational plasticity within BamA across differing bacterial species. [Display omitted] • The POTRA domains of BamA are known to be flexible • Crystal structures of A. baumannii BamA POTRA domains reveal novel conformations • MD simulations and SAXS data are consistent with the crystal structures • These new conformations may explain how Bam components become surface exposed In A. baumannii , BamA has an N-terminal periplasmic domain consisting of five tandem POTRA domains. Overly Cottom et al. determined crystal structures of AbBamA POTRAs 1–4, revealing new conformations that are rotated by ∼180°, indicating even more conformational plasticity than has been observed previously and offering a possible explanation for surface exposure of accessory proteins. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii , a predominant nosocomial pathogen, represents a grave threat to public health due to its multiple antimicrobial resistance. Managing patients afflicted with severe infections caused by multiple drug-resistant A. baumannii is particularly challenging, given the associated high mortality rates and unfavorable prognoses. The diminishing efficacy of antibiotics against this superbug underscores the urgent necessity for novel treatments or strategies to address this formidable issue. Bacteriophage-derived polysaccharide depolymerase enzymes present a potential approach to combating this pathogen. These enzymes target and degrade the bacterial cell's exopolysaccharide, capsular polysaccharide, and lipopolysaccharide, thereby disrupting biofilm formation and impairing the bacteria's defense mechanisms. Nonetheless, the narrow host range of phage depolymerases limits their therapeutic efficacy. Despite the benefits of these enzymes, phage-resistant strains have been identified, highlighting the complexity of phage-host interactions and the need for further investigation. While preliminary findings are encouraging, current investigations are limited, and clinical trials are imperative to advance this treatment approach for broader clinical applications. This review explores the potential of phage-derived depolymerase enzymes against A. baumannii infections. [ABSTRACT FROM AUTHOR]

Background: Acinetobacter baumannii is a gram-negative, opportunistic pathogen, that is responsible for a wide variety of infections and is a significant cause of hospital-acquired infections. A. baumannii is listed by the World Health Organization (WHO) as a critical priority pathogen because of its high level of antibiotic resistance and the urgent need for alternative treatment solutions. To address this challenge, bacteriophages have been used to combat bacterial infections for more than a century, and phage research has regained interest in recent years due to antimicrobial resistance (AMR). However, although the vast majority of deaths from the AMR crisis will occur in developing countries in Africa and Asia, few phages' studies have been conducted in these regions. In this study, we present a comprehensive characterization of the bacteriophages vAbBal23 and vAbAbd25, actives against extremely drug-resistant (XDR) A. baumannii. Methods: Phages were isolated from environmental wastewaters in Dakar, Senegal. The host-range, thermal and pH stabilities, infection kinetics, one step growth assay, antibiofilm activity assay, sequencing, and genomic analysis, were performed to characterize the isolated phages. Results: Comparative genomic and phylogenetic analyses revealed that vAbBal23 and vAbAbd25 belong to the Caudoviricetes class, Autographiviridae family and Friunavirus genus. Both phages demonstrated activity against strains with capsular type KL230. They were stable over a wide pH range (pH 3 to 9) and at temperatures ranging from 25 °C to 40 °C. Additionally, the phages exhibited notable activity against both planktonic and biofilm cells of targeted extremely drug resistant A. baumannii. The results presented here indicate the lytic nature of vAbBal23 and vAbAbd25. This is further supported by the absence of genes encoding toxins, resistance genes and bacterial virulence factors, highlighting their potential for future phage applications. Conclusion: Phages vAbBal23 and vAbAbd25 are promising biological agents that can infect A. baumannii, making them suitable candidates for use in phage therapies. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii's extensive antibiotic resistance makes its infections difficult to treat, so effective strategies to fight this bacterium are urgently needed. This study aims to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) mediated by Rutin-Gal(III) complex and Quercetin against A. baumannii. Absorbance spectra, fluorescence spectra, and minimum inhibitory concentration (MIC) of Rutin-Gal(III) complex and Quercetin were determined. The intracellular reactive oxygen species (ROS), extracellular polymeric substances (EPS), cell membrane permeability, expression of ompA and blaOXA−23, anti-biofilm activity, and anti-metabolic activity of Rutin-Gal(III) complex- and Quercetin-mediated aPDT were measured. Rutin-Gal(III) complex and Quercetin revealed absorption peaks in the visible spectra. Quercetin and Rutin-Gal(III) complex displayed fluorescence peaks at 524 nm and 540 nm, respectively. MIC values for the Rutin-Gal(III) complex and Quercetin were 64 µg/mL and 256 µg/mL, respectively. Quercetin- and Rutin-Gal(III) complex-mediated aPDT significantly reduced the colony forming units/mL (58.4% and 67.5%), EPS synthesis (47.4% and 56.5%), metabolic activity (30.5% and 36.3%), ompA (5.5- and 10.5-fold), and blaOXA−23 (4.1-fold and 7.8-fold) genes expression (respectively; all P < 0.05). Quercetin- and Rutin-Gal(III) complex-mediated aPDT enhanced notable biofilm degradation (36.2% and 40.6%), ROS production (2.55- and 2.90-folds), and membrane permeability (10.8– and 9.6-folds) (respectively; all P < 0.05). The findings indicate that Rutin-Gal(III) complex- and Quercetin-mediated aPDT exhibits antibacterial properties and could serve as a valuable adjunctive strategy to conventional antibiotic treatments for A. baumannii infections. One limitation of this study is that it was conducted solely on the standard strain; testing on clinical isolates would allow for more reliable interpretation of the results. [ABSTRACT FROM AUTHOR]

Metallo‐β‐lactamases (MBLs), enzymes of class B, employ zinc ions to degrade β‐lactam antibiotics such as penicillins, cephalosporins, carbapenems, and cephamycins. Carbapenem‐resistant Acinetobacter baumannii (CRAB) is linked to the existence of carbapenemase enzymes such as oxacillinase and MBL. The most prevalent resistance mechanisms include imipenemases (IMP), verona integron‐encoded MBL, and New Delhi MBL‐1. The effectiveness of current antibiotics against the MBL enzyme is limited due to the presence of metal ions, underscoring the need for new antimicrobial agents. Recent research has demonstrated that natural compounds can effectively inhibit MBL. This study aims to screen natural phytochemicals against IMP‐2 MBL using in silico virtual screening techniques via AutoDock Vina and molecular dynamic simulations with GROMACS for 200 ns, followed by molecular mechanics/Poisson‒Boltzmann surface area analysis. This procedure identified new lead molecules against A. baumannii that produce IMP. A total of 588 natural compounds were screened against IMP, along with the imipenem substrate and known inhibitors of L‐captopril. The top four compounds, N025‐0038 (NC1), N062‐0008 (NC2), eupalitin, and Rosmorinic acid, demonstrated binding affinities of ‒8.5, ‒8.4, ‒7.5, and ‒7.2 kcal/mol, respectively. The structural stability of these complexes was observed to be maintained throughout the simulation in a dynamic environment, as determined by molecular dynamics trajectory analysis, and all these compounds met the SWISS‐ADME (adsorption, distribution, metabolism, and excretion) properties. NC1 and NC2 compounds are considered potential drug molecules against IMP. However, while these selected compounds showed superior binding energy in computational analysis, further in vitro analysis is required to establish an effective drug regimen against A. baumannii that produces IMP. [ABSTRACT FROM AUTHOR]

The rise of antibiotic-resistant bacteria in clinical settings has become a significant global concern. Among these bacteria, Acinetobacter baumannii stands out due to its remarkable ability to acquire resistance genes and persist in hospital environments, leading to some of the most challenging infections. Horizontal gene transfer (HGT) plays a crucial role in the evolution of this pathogen. The A. baumannii AMA205 strain, belonging to sequence type ST79, was isolated from a COVID-19 patient in Argentina in 2021. This strain's antimicrobial resistance profile is notable as it harbors multiple resistance genes, some of which had not been previously described in this species. The AmpC family β-lactamase blaCMY-6, commonly found in Enterobacterales, had never been detected in A. baumannii before. Furthermore, this is the first ST79 strain known to carry the carbapenemase blaNDM-1 gene. Other acquired resistance genes include the carbapenemase blaOXA-23, further complicating treatment. Susceptibility testing revealed high resistance to most antibiotic families, including cefiderocol, with significant contributions from blaCMY-6 and blaNDM-1 genes to the cephalosporin and carbapenem resistance profiles. The A. baumannii AMA205 genome also contains genetic traits coding for 111 potential virulence factors, such as the iron-uptake system and biofilm-associated proteins. This study underscores A. baumannii's ability to acquire multiple resistance genes and highlights the need for alternative therapies and effective antimicrobial stewardship to control the spread of these highly resistant strains. [ABSTRACT FROM AUTHOR]

Background: Management of complicated intraabdominal infections (cIAIs) requires containment of the source and appropriate initial antimicrobial therapy. Identifying the local data is important to guide the empirical selection of antimicrobial therapy. In this study, we aimed to describe the pathogen distribution and antimicrobial resistance of cIAI. Methods: In two major tertiary care hospitals in Egypt, we enrolled patients who met the case definition of cIAI from October 2022 to September 2023. Blood cultures were performed using the BACTAlert system (BioMerieux, Marcy l'Etoile, France). A culture of aspirated fluid, resected material, or debridement of the infection site was performed. Identification of pathogens and antimicrobial susceptibility testing were conducted by the VITEK-2 system (BioMerieux, Marcy l'Etoile, France). Gram-negative resistance genes were identified by PCR and confirmed by whole bacterial genome sequencing using the Nextera XT DNA Library Preparation Kit and sequencing with the MiSeq Reagent Kit 600 v3 (Illumina, USA) on the Illumina MiSeq. Results: We enrolled 423 patients, 275 (65.01%) males. The median age was 61.35 (range 25–72 years). We studied 452 recovered bacterial isolates. Gram-negative bacteria were the vast majority, dominated by E. coli, followed by Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Proteus mirabilis (33.6%, 30.5%, 13.7%, 13%, and 5.4%, respectively). High rates of resistance were detected to third- and fourth-generation cephalosporins and fluoroquinolones. No resistance was detected to colistin. Resistance to amikacin and tigecycline was low among all isolates. Resistance to meropenem and ceftazidime/avibactam was moderate. ESBL genes were common in E. coli and K. pneumoniae. CTX-M15 gene was the most frequent. Among Enterobacterales, blaOXA-48 and blaNDM were the most prevalent carbapenemase genes. Pseudomonas aeruginosa isolates harbored a wide variety of carbapenemase genes (OXA, NDM, VIM, SIM, GIM, SPM, IMP, AIM), dominated by metallo-beta-lactamases. In 20.6% of isolates, we identified two or more resistance genes. Conclusion: High resistance rates were detected to third- and fourth-generation cephalosporins and fluoroquinolones. Amikacin and tigecyclines were the most active antimicrobials. Our data call for urgent implementation of antimicrobial stewardship programs and reinforcement of infection control. [ABSTRACT FROM AUTHOR]

Purpose: Predicting infection risk in carbapenem-resistant Acinetobacter baumannii (CRAB) colonized patients may help in improving timely appropriate antibiotic therapy. This study aims to explore risk factors for developing infections in hospitalized patients with previous CRAB colonization. Methods: We performed an observational retrospective cohort study at ASST Sette Laghi-Varese Hospital between January 2020 and December 2022. All consecutive adult (> 18 years old) hospitalized patients with documented colonization by CRAB at any anatomical site or with CRAB infections preceded by CRAB colonization were included. Univariate and multivariate analyses were performed to investigate infection risk factors. Results: Overall, 144 patients were included in the study: 104 colonized only and 40 infected patients. Colonization and infection rates significantly changed over the years (2020–2022, p < 0.001). The incidence of infections in CRAB carriers was 27.8% (40/144). Median time from colonization to infection was 4 days (IQR 1-8.5). Overall, inhospital mortality was 32.7% and 55.0% in colonized only and infected patients, respectively. At the multivariable logistic regression cardiovascular disease (OR 5.83, 95% CI 1.12–30.43, p = 0.037), COVID-19 (OR 3.72, 95% CI 1.16–11.91, p = 0.027) and intensive care unit (ICU) admission (OR 8.83, 95% CI 2.94–26.51, p < 0.001) were risk factors independently associated with cardiovascular disease CRAB infection after colonization. Conclusions: We observed an increased infection risk in patients colonized with CRAB with cardiovascular disease, COVID-19 and admitted in ICU setting. Additional evidence is needed to identify predictors of infection in colonized patients. [ABSTRACT FROM AUTHOR]

Objectives To investigate the characteristics and clonal dynamics of tigecycline-resistant Acinetobacter baumannii (TRAB) isolates from a Chinese hospital from 2016 to 2021. Methods A total of 64 TRAB isolates were screened and WGS was performed. Phylogenetic analysis and non-polymorphic mutation analysis were used to analyse their clonal dynamics and tigecycline resistance-related mutations. RT-PCR was used to analyse the expression of the resistance-nodulation cell-division (RND) efflux pump genes adeB and adeJ. Gene cloning was used to explore the effect of tet (39) variants on tigecycline resistance. Results Most TRAB isolates were found to be MDR, with 95% (61/64) of the isolates showing resistance to carbapenems. These TRAB isolates were classified into three primary genetic clusters based on core-genome SNPs. The KL2 cluster persisted throughout the study period, whereas the KL7 cluster emerged in 2019 and became the dominant clone. The KL7 cluster carried more antimicrobial resistance genes than the other two clusters. The predominant tigecycline resistance mechanism of the KL2 cluster and KL7 cluster was IS insertion in adeN (82.1%, 23/28) and genetic alterations in adeS (76.2%, 16/21), respectively. Eleven novel AdeS mutations were identified associated with elevated AdeB expression and tigecycline resistance. Moreover, we characterized a plasmid-borne tet (39) variant with an Ala-36-Thr substitution that synergizes with the RND efflux pump to confer high-level tigecycline resistance. Conclusions This work provides important insights into the diverse mechanisms associated with tigecycline resistance in A. baumannii , highlighting a pressing need for further monitoring of ST2-KL7 A. baumannii in clinical settings. [ABSTRACT FROM AUTHOR]

Background: For patients with pneumonia, the rapid detection of pathogens is still a major global problem in clinical practice because traditional diagnostic techniques for infection are time-consuming and insensitive. Metagenomic next-generation sequencing (mNGS) is a novel technique that has the potential to improve pathogen diagnosis. This study aimed to investigate the microbiological diagnostic ability of mNGS compared with conventional culture and to determine the optimal time to test patients for pneumonia. Methods: A prospective study using data from June 2020 to June 2021 was performed at a tertiary teaching hospital in China. We included 56 patients from all adult patients with a clinical diagnosis of pneumonia. Blood and bronchoalveolar lavage fluid (BALF) samples were taken for simultaneous mNGS and conventional culture testing. Results: All 56 patients underwent both conventional culture and mNGS. Of these patients, 37 were diagnosed with severe pneumonia and 17 were diagnosed with non-severe pneumonia. The top three pathogenic bacteria detected by mNGS were Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Enterococcus faecium was detected more frequently in the non-severe pneumonia group (4 vs. 0, p < 0.05). The findings revealed that the detection rate of mNGS (84%) was superior to that of conventional culture methods (48%). Notably, the percentage of mNGS-positive BALF samples (46/56, 82.14%) was significantly greater than that of blood samples (27/56, 48.21%). The etiological comparison demonstrated that mNGS-positive samples, which received clinical approval, tended to be associated with a more normalized temperature, lower PCO2 levels, and a higher SOFA score than mNGS-negative samples (p = 0.022, p = 0.0.028, and p = 0.038, respectively). Conclusions: In this study, we discovered that the etiology of lung infections frequently involves multiple pathogens. The use of mNGS in BALF is instrumental for detecting nonviral pathogens associated with lung infections. Although the rate of positive blood NGS results is significantly influenced by various clinical factors, for patients suspected of having viral, Legionella, or tsutsugamushi infections, plasma mNGS could serve as a complementary diagnostic tool. [ABSTRACT FROM AUTHOR]

This work examined the antibacterial and antibiofilm properties of alginate/collagen nanoparticles containing limonene. The multi-drug resistant (MDR) strains were screened, and the morphological features of the produced nanoparticles were determined utilizing SEM, DLS, and FTIR. Additionally, the encapsulation effectiveness, stability, and drug release were assessed. The levels of OmpA and Bap biofilm genes were assessed using qRT-PCR. At the same time, the antibacterial and cytotoxic activities of the nanoparticles were evaluated using well diffusion and MTT techniques, respectively. LAC nanoparticles measuring 300 ± 9.6 nm in size, 83.64 ± 0.19% encapsulation efficiency, and 60-day stability at 4 °C were synthesized. The biological investigation demonstrated that LAC nanoparticles had potent antibacterial capabilities. This was shown by their ability to significantly decrease the transcription of OmpA and Bap biofilm genes at a statistically significant level of p ≤ 0.05. The nanoparticles exhibited reduced antibiotic resistance compared to free limonene and alginate/collagen. Compared to limonene, LAC nanoparticles exhibited negligible cytotoxicity against HEK-293 at doses ranging from 1.56 to 100 µg/mL (p ≤ 0.01). The findings underscore the potential of LAC nanoparticles as a breakthrough in the fight against highly resistant pathogens. The potent antibacterial effects of LAC nanoparticles versus Acinetobacter baumannii (A. baumannii) MDR strains, considered highly resistant pathogens of significant concern, could inspire new strategies in antibacterial research. [ABSTRACT FROM AUTHOR]

Essential oils are promising antimicrobial agents against various bacteria. The aim of the study was to examine anti- Acinetobacter baumannii activity of nine essential oils and to elucidate essential oil mechanisms of action against this. In total, 8 out of 9 examined different essential oils exhibited activity against multidrug-resistant (MDR) A. baumannii isolates. The best anti- A. baumannii activity expressed Thymus serpyllum, Satureja hortensis and Oreganum majorana essential oil (MBC 1.29 to 2.58 µg mL−1), while essential oils of Menta x piperita, Hyssopus officinalis, Foeniculum vulgare and Artemisia dracunculus expressed the same effect in higher concentrations (1.80 to 3.80 µg mL−1). The effect of Juniperus sabina, Juniperus sibirica and S. hortensis essential oils against A. baumannii is for the first time reported here. The mechanisms of Myrtus communis, Eucalyptus camaldulensis, S. hortensis and T. serpyllum essential oils were further examined. The essential oil treatments led to concentration dependent leakage of biomolecules form the cells, causing an increase in the concentrations of lipids, carbohydrates, and proteins in the suspensions. Microstructural observations confirmed the essential oil effect on cell membranes and disruption the membrane integrity, with obvious leakage of intercellular substance, collapsed cells with perforations, debris presence and autoaggregated cells. The subinhibitory concentrations of oils did not obviously changed protein patterns determined by SDS-PAGE. These results indicate that the essential oils, particularly T. serpyllum, S. hortensis, M. communis and E. camaldulensis express its anti- A. baumannii activity via membrane disruption and increased membrane permeability, representing very promising alternative antibacterial agents against MDR wound isolates. [Display omitted] • Essential oils (EO) exhibit promising antimicrobial activity against MDR A.baumannii. • M. communis, E. camaldulensis, S. hortensis, T. serpyllum EOs disrupt membranes. • EOs increase cell autoaggregation, membrane permeability and biomolecules leakage. • Microstructural observations confirmed cell collapse, perforations, debris presence. • Subinhibitory concentrations of oils did not significantly alter protein patterns. [ABSTRACT FROM AUTHOR]

• Presenting a facile method using pink flower petals as a new source of green synthesis of silver nanoparticles. • SEM analysis showed that the biosynthesized nanoparticles with pink rose petals had a spherical shape and an average size of 26 nm. • Biosynthesized nanoparticles have Ag0 structure. • Biosynthesized silver nanoparticles with a new synthesis source have antibacterial effects, the lowest minimum inhibitory concentration (MIC) of silver nanoparticles is 400 μg/ml against multidrug-resistant Staphylococcus aureus and MIC on multidrug-resistant Escherichia coli, Acinetobacter baumannii , and resistant Acinetobacter. It was 800 µg/ml, 3200 µg/ml and 1600 µg/ml, respectively, to several drugs and Klebsiella pneumoniae. Drug resistant bacterial infections can be fatal for disabled people needing multiple medications and new effective antibacterial drugs such as biosynthesized nanoparticles are needed. A cost-effective and green method was studied for the biosynthesis of silver nanoparticles using pink rose petals. Silver nanoparticles (AgNP) were synthesized using the petals of pink rose flowers. The AgNPs were characterized using FITR, SEM, XRD, and EDS analyses. The antibacterial activity of the AgNPs against multidrug-resistant bacterial pathogens Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii , and colistin-resistant Klebsiella pneumoniae were studied using the microplate method. Th AgNPs had a spherical shape and an average size of 26 nm. XRD analysis showed that the nanoparticles were Ag0. Antibacterial activity was the highest against the multidrug-resistant S. aureus the minimum inhibitory concentration (MIC) being 400 µg/ml AgNPs. The multidrug-resistant E. coli , multidrug-resistant A. baumannii , and colistin-resistant K. pneumoniae MICs were 800 µg/ml, 3200 µg/ml, and 1600 µg/ml, respectively. The green synthesized of AgNPS using pink rose petals and their antibacterial effects offer material for the treatments of common multidrug-resistant bacterial pathogens. [ABSTRACT FROM AUTHOR]

The spread of carbapenemase-producing gram-negative pathogens, especially those producing metallo-β-lactamases (MBLs), has become a major health concern. MBLs are molecularly the most diverse carbapenemases, produced by a wide spectrum of gram-negative organisms, including the Enterobacterales, Pseudomonas spp., Acinetobacter baumannii, and Stenotrophomonas maltophilia, and can hydrolyze most β-lactams using metal ion cofactors in their active sites. Over the years, the prevalence of MBL-carrying isolates has increased globally, particularly in Asia. MBL infections are associated with adverse clinical outcomes including longer length of hospital stay, ICU admission, and increased mortality across the globe. The optimal treatment for MBL infections not only depends on the pathogen but also on the underlying resistance mechanisms. Currently, there are only few drugs or drug combinations that can efficiently offset MBL-mediated resistance, which makes the treatment of MBL infections challenging. The rising concern of MBLs along with the limited treatment options has led to the need and development of drugs that are specifically targeted towards MBLs. This review discusses the prevalence of MBLs, their clinical impact, and the current treatment options for MBL infections and their limitations. Furthermore, this review will discuss agents currently in the pipeline for treatment of MBL infections. [ABSTRACT FROM AUTHOR]

BamA, an Omp85 superfamily member, is universally conserved and essential for cell viability. Using anti‐Oma87 antibodies, we focus on understanding the effect of Oma87 of Acinetobacter baumannii on pathogenicity. Oma87 was expressed, purified, and used to induce anti‐Oma87 antibodies in BALB/c mice. Acute toxicity of the protein was evaluated in mice. HeLa cells were infected with both live and killed A. baumannii 19606 and a clinical isolate. The effects of anti‐Oma87 sera on A. baumannii adherence, internalization, and proliferation in HeLa cells were studied. The roles of microfilaments and microtubules in A. baumannii invasion were demonstrated by Actin disruption. Reduced bacterial population and biofilm formation were noted. The ability of A. baumannii to provoke autophagy through Oma87 induction leads to incomplete autophagy and potentially facilitates bacterial replication. Actin‐mediated uptake, attachment, and invasion demonstrated A. baumannii survival and multiplication within vacuoles in the host cell. The findings underscore the potential of Oma87 as a therapeutic intervention target in infections caused by A. baumannii. This comprehensive analysis contributes valuable information for understanding the virulence mechanisms of A. baumannii, potentially guiding future strategies to combat infections caused by this pathogen. [ABSTRACT FROM AUTHOR]

Bacterial biofilms pose significant challenges due to their association with antibiotic resistance, metabolic adaptation, and survival under harsh conditions. Among notable pathogens forming biofilms, Staphylococcus aureus and Acinetobacter baumannii are concerning pathogens in nosocomial settings. However, their behaviour under acidic (pH 4.5) and alkaline (pH10.5) conditions, especially in co-culture setups, remains insufficiently understood. This study investigates these aspects, by examining growth rates, biofilm formation, pH shifts, phenotypic analysis, and gene expression profiles. The results showed A. baumannii exhibited reduced growth and biofilm formation at pH 4.5, while S. aureus showed slow growth and low biofilm formation at pH10.5 in mono-cultures. S. aureus leaned towards an acidic pH (6–6.5), whereas A. baumannii shifted towards an alkaline pH (8–9). In co-culture environments, growth rates and biofilm formation increased across all pH conditions, converging towards a neutral pH over time. Phenotypic motility assays indicated that A. baumannii exhibited greater motility in alkaline conditions, while S. aureus showed increased staphyloxanthin production under acidic conditions. Gene expression analyses revealed that the fibronectin-binding protein A (FnbA) and N-acetylglucosaminyl-transferase (icaA) genes, responsible for initial attachment during biofilm formation, were highly expressed in acidic co-culture condition but poorly expressed in alkaline condition. In A. baumannii, the outer membrane protein A (OmpA) gene associated with adhesion and virulence, was upregulated in co-culture. The LuxR gene involved in quorum sensing was upregulated in acidic conditions and poorly expressed at pH 10.5. This study elucidates the metabolic adaptability and biofilm formation tendencies of S. aureus towards acidic conditions and A. baumannii towards alkaline conditions, providing insights for better management of biofilm-related infections. [ABSTRACT FROM AUTHOR]

Background: Concerns are arising about Acinetobacter baumannii (A. baumannii) gaining resistance to tigecycline (TGC). AdeB efflux pump gene has been strongly associated with TGC resistance and usnic acid (UA) has been postulated to act as an efflux pump inhibitor. This study aimed at determining the antibacterial effect of UA and its effect on TGC susceptibility and on adeB gene expression in TGC non susceptible multidrug resistant (MDR) A. baumannii clinical isolates. Methods: Fifty multidrug resistant Acinetobacter baumannii isolates were identified as TGC resistant using disc diffusion method (DD). Minimal inhibitory concentration (MIC) of TGC and UA were determined using microbroth dilution (MBD) test. Checkerboard synergy test was conducted on TGC non susceptible isolates to determine UA effect on MIC of TGC. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure adeB gene expression before treatment, after treatment with TGC alone and with TGC/UA combination. Results: Tigecycline non susceptibility determined by MIC values occurred in 44/50 (88%) isolates. UA had antibacterial activity against 44/44(100%) of the isolates. Reduction in MIC of TGC in response to UA was detected in 10/44 (22.3 %) isolates in which high adeB gene expression was detected. In addition, 9/10 (90%) of them revealed highly significant reduction in adeB gene expression after treatment with TGC/UA combination. Conclusion: UA has an in vitro antibacterial action against TGC non susceptible A. baumannii with the potential ability of TGC and UA to synergistically act against them. Such synergism can be significantly attributed to UA efflux pump inhibitory action. [ABSTRACT FROM AUTHOR]

Background: Carbapenem-resistant A. baumannii pose a serious threat, limiting treatment options for severe infections induced by this emerging pathogen. This study aimed to evaluate the antimicrobial resistance profile and detect resistance mechanisms in imipenem-resistant A. baumannii from various Egyptian hospitals. Materials and Methods: A total of 59 A. baumannii isolated from various clinical specimens (blood, sputum, wound swap, urine and endotracheal tubes) collected from the microbiology lab of different Egyptian hospitals. Isolates were identified using conventional bacteriological methods. Antimicrobial susceptibility was tested using Kirby-Bauer disc diffusion method. Biofilm formation was determined spectrophotometrically using microtiter plate method. Metallo-β-lactamase (MBL) resistance was determined by combined disk test (CDT). Multiplex PCR evaluated MBL-encoding genes in imipenem-resistant isolates. Additionally, PCR was used to detect class 1 integrons in MBL-producing isolates. Results: Strong biofilm production was observed in 74% (17/23) of isolates. Class 1 integron was detected in 78.9 % (15/19) of MBL producing isolates. Out of 23 isolates 19 (32.2%) were MBL producers by CDT. Among the 19 (32.2%) CDT-positive isolates, 11 (57.9%) isolates harboured MBL encoding gene (blaNDM). Conclusion: Our findings highlight the emergence and dissemination of blaNDM in our hospitals, coupled with their biofilms and MBL production ability, represents a major public health challenge. The presence of class 1 integrons in all isolates carrying MBL-encoding gene, suggesting the critical role of Class 1 integrons in the dissemination of resistance genes. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii is an opportunistic Gram‐negative bacterium representing one of the leading causes of ventilator‐associated pneumonia. The development of pneumonia results from a complex interplay between pathogens and pulmonary innate mucosal immunity. Therefore, the knowledge of the host immune responses is pivotal for the development of effective therapeutics to treat A. baumannii infections. Previous studies were conducted using cell lines and animal models, but a comprehensive understanding of the interaction between A. baumannii and primary human immune cells is still lacking. To bridge this gap, we investigated the response of primary monocytes, macrophages, and dendritic cells to the A. baumannii‐type strain and an epidemic clinical isolate. We found that all immune cells trigger different responses when interacting with A. baumannii. In particular, macrophages and monocytes mediate bacterial clearance, whereas monocytes and dendritic cells activate a late response through the production of cytokines, chemokines, and the expression of co‐stimulatory molecules. The epidemic strain induces lower expression of interleukin‐10 and CD80 compared with the type strain, potentially constituting two immune evasion strategies. [ABSTRACT FROM AUTHOR]

Tigecycline (TGC) is currently used to treat carbapenem-resistant Acinetobacter baumannii (CRAB) infections, while eravacycline (ERV), a new-generation tetracycline, holds promise as a novel therapeutic option for these infections. However, differences in resistance mechanism between ERV and TGC against A. baumannii remain unclear. This study sought to compare the characteristics and mechanisms of ERV and TGC resistance among clinical A. baumannii isolates. A total of 492 isolates, including 253 CRAB and 239 carbapenemsensitive A. baumannii (CSAB) isolates, were collected from hospitalized patients in China. The MICs of ERV and TGC against A. baumannii were determined by broth microdilution. Genetic mutations and expressions of adeB, adeG, adeJ, adeS, adeL, and adeN in resistant strains were examined by PCR and qPCR, respectively. The in vitro recombination experiments were used to verify the resistance mechanism of ERV and TGC in A. baumannii. The MIC90 of ERV in CRAB and CSAB isolates were lower than those of TGC. A total of 24 strains resistant to ERV and/or TGC were categorized into three groups: only ERVresistant (n = 2), both ERV- and TGC-resistant (n = 7), and only TGC-resistant (n = 15). ST208 (75%, n = 18) was a major clone that has disseminated in all three groups. The ISAba1 insertion in adeS was identified in 66.7% (6/9) of strains in the only ERV-resistant and both ERV- and TGC-resistant groups, while the ISAba1 insertion in adeN was found in 53.3% (8/15) of strains in the only TGC-resistant group. The adeABC and adeRS expressions were significantly increased in the only ERV-resistant and both ERV- and TGC-resistant groups, while the adeABC and adeIJK expressions were significantly increased and adeN was significantly decreased in the only TGC-resistant group. Expression of adeS with the ISAba1 insertion in ERV- and TGC-sensitive strains significantly increased the ERV and TGC MICs and upregulated adeABC and adeRS expressions. Complementation of the wildtype adeN in TGC-resistant strains with the ISAba1 insertion in adeN restored TGC sensitivity and significantly downregulated adeIJK expression. In conclusion, our data illustrates that ERV is more effective against A. baumannii clinical isolates than TGC. ERV resistance is correlated with the ISAba1 insertion in adeS, while TGC resistance is associated with the ISAba1 insertion in adeN or adeS in A. baumannii. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a persistent nosocomial pathogen that poses a significant threat to global public health, particularly in intensive care units (ICUs). Here we report a three-month longitudinal genomic surveillance study conducted in a Hangzhou ICU in 2021. This followed a three-month study conducted in the same ICU in 2019, and infection prevention and control (IPC) interventions targeting patients, staff and the ICU environment. Most A. baumannii isolated in this ICU in 2021 were CRAB (80.9%; 419/518) with higher-level resistance to carbapenems. This was accompanied by the proportion of global clone 2 (GC2) isolates falling from 99.5% in 2019 to 50.8% (213/419) in 2021. The phylogenetic diversity of GC2 increased, apparently driven by regular introductions of distinct clusters in association with patients. The remaining CRAB (40.2%; 206/419) were a highly clonal population of ST164. Isolates of ST164 carried blaNDM-1 and blaOXA-23 carbapenemase genes, and exhibited higher carbapenem MIC50/MIC90 values than GC2. Comparative analysis of publicly available genomes from 26 countries (five continents) revealed that ST164 has evolved towards carbapenem resistance on multiple independent occasions. Its success in this ICU and global capacity for acquiring resistance determinants indicate that ST164 CRAB is an emerging high-risk lineage of global concern. Carbapenem-resistant Acinetobacter baumannii is an important nosocomial pathogen that can cause outbreaks. In 2019, these authors conducted a genomic surveillance study of A baumannii in an intensive care unit in China, and here they report findings from a follow up study in 2021. [ABSTRACT FROM AUTHOR]

The COVID‐19 pandemic has intensified the issue of multidrug‐resistant (MDR) infections, particularly in intensive care units (ICUs). This study documents the first known case of coinfection with two extensively drug‐resistant (XDR) bacterial isolates in a critically ill patient with COVID‐19 in Saudi Arabia. Both XDR isolates were recovered from blood and were resistant to all tested antimicrobial agents except colistin. Whole genome sequencing (WGS) revealed that the K. pneumoniae isolate KP‐JZ107 had sequence type 11 (ST11) and core genome MLST (cgMLST 304742), while the A. baumannii isolate AB‐JZ67 had ST2 and cgMLST 785. KP‐JZ107 was found to possess the virulence plasmid KpVP‐type‐1, carbapenemase genes blaNDM and blaKPC, and numerous antimicrobial‐resistant genes (ARGs). The AB‐JZ67 isolate had several biofilm‐related genes, including biofilm‐associated protein (BAP), csuE, and pgaB, and multiple ARGs, including blaADC−25, blaOXA−23, and blaOXA−66. Our findings suggest that the coexistence of KP‐JZ107 and AB‐JZ67 isolates may indicate their widespread presence in ICUs, requiring comprehensive surveillance studies across all hospitals. [ABSTRACT FROM AUTHOR]

Background: Microecological equilibrium is essential for human health. Previous research has demonstrated that Streptococcus strain A, the main bacterial group in the respiratory tract, can suppress harmful microbes and protect the body. In this study, Streptococcus strain D19T was isolated from the oral and pharyngeal cavities of healthy children. Its antibacterial mechanism against Acinetobacter baumannii was examined, as well as its potential to prevent inflammatory damage to cells. We evaluated the effect of the fermentation conditions of D19T on inhibition of Acinetobacter baumannii growth; Isolation and purification of antibacterial active components of strain D19T and molecular mechanism of inhibition of Acinetobacter baumannii; Molecular mechanism of D19T antibacterial protein reversing cellular inflammatory injury induced by Acinetobacter baumannii. Results: The supernatant of fermentation broth of Streptococcus D19T was the active component against Acinetobacter baumannii, but the bacteria had no antibacterial activity. The supernatant of D19T fermentation broth was precipitated by (NH4)2SO4 solution, and the protein was the active antibacterial component. After gel filtration chromatography and anion gel filtration chromatography, the molecular weight of antibacterial protein was 53kD. D19T antibacterial protein can improve cell membrane permeability, limit extracellular soluble protein release, inhibit Acinetobacter baumannii biofilm formation, and prevent Acinetobacter baumannii adhesion. Acinetobacter baumannii induces inflammatory damage to respiratory cells via ferroptosis, and the D19T antibacterial protein can counteract this damage, protecting the respiratory tract. Conclusion: Streptococcus strain D19T, as a potential probiotic, inhibits the growth of Acinetobacter baumannii and the inflammatory damage of respiratory cells, playing a protective role in human respiratory health. [ABSTRACT FROM AUTHOR]

Background: The extensively drug-resistant (XDR) strains of Acinetobacter baumannii have become a major cause of nosocomial infections, increasing morbidity and mortality worldwide. Many different treatments, including phage therapy, are attractive ways to overcome the challenges of antibiotic resistance. Methods: This study investigates the biofilm formation ability of 30 XDR A. baumannii isolates and the efficacy of a cocktail of four tempetate bacteriophages (SA1, Eve, Ftm, and Gln) and different antibiotics (ampicillin/sulbactam, meropenem, and colistin) in inhibiting and degrading the biofilms of these strains. Results: The majority (83.3%) of the strains exhibited strong biofilm formation. The bacteriophage cocktail showed varying degrees of effectiveness against A. baumannii biofilms, with higher concentrations generally leading to more significant inhibition and degradation rates. The antibiotics-bacteriophage cocktail combinations also enhanced the inhibition and degradation of biofilms. Conclusion: The findings suggested that the bacteriophage cocktail is an effective tool in combating A. baumannii biofilms, with its efficacy depending on the concentration. Combining antibiotics with the bacteriophage cocktail improved the inhibition and removal of biofilms, indicating a promising strategy for managing A. baumannii infections. These results contribute to our understanding of biofilm dynamics and the potential of bacteriophage cocktails as a novel therapeutic approach to combat antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

Background: The combination antimicrobial therapy consisting of amikacin, polymyxin-B, and sulbactam demonstrated in vitro synergy against multi-drug resistant Acinetobacter baumannii. Objectives: The objectives were to predict drug disposition and extrapolate their efficacy in the blood, lung, heart, muscle and skin tissues using a physiologicallybased pharmacokinetic (PBPK) modeling approach and to evaluate achievement of target pharmacodynamic (PD) indices against A. baumannii. Methods: A PBPK model was initially developed for amikacin, polymyxin-B, and sulbactam in adult subjects, and then scaled to pediatrics, accounting for both renal and non-renal clearances. The simulated plasma and tissue drug exposures were compared to the observed data from humans and rats. Efficacy was inferred using joint probability of target attainment of target PD indices. Results: The simulated plasma drug exposures in adults and pediatrics were within the 0.5 to 2 boundary of the mean fold error for the ratio between simulated and observed means. Simulated drug exposures in blood, skin, lung, and heart were consistent with reported penetration ratio between tissue and plasma drug exposure. In a virtual pediatric population from 2 to <18 years of age using pediatric dosing regimens, the interpretive breakpoints were achieved in 85-90% of the population. Conclusion: The utility of PBPK to predict and simulate the amount of antibacterial drug exposure in tissue is a practical approach to overcome the difficulty of obtaining tissue drug concentrations in pediatric population. As combination therapy, amikacin/polymyxin-B/sulbactam drug concentrations in the tissues exhibited sufficient penetration to combat extremely drug resistant A. baumannii clinical isolates. [ABSTRACT FROM AUTHOR]

Introduction: The Seraph® 100 Microbind® Affinity Filter is a biomimetic adsorbent device that can remove pathogens from the blood. Case Presentation: Here, we report the successful use of the Seraph® 100 to treat both a SARS-CoV-2 reinfection leading to severe COVID-19 pneumonia as well as subsequent secondary lung infections including Acinetobacter baumannii, Serratia marcescens, and Pseudomonas aeruginosa multidrug-resistant bacteria. To our knowledge, this 46-year-old black male is the first patient in which four treatments with this pathogen adsorber, one for a viral and three for different bacterial infections, have been successfully used. Conclusion: The Seraph® 100 can be easily and successfully used in conjunction with standard (anti-infective) treatment. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the presence of ESKAPE organisms on the hands of students working in the intensive care unit (ICU) at a veterinary academic hospital. Methods: A cross-sectional study was conducted among students working in an ICU at a veterinary academic hospital in South Africa. Students were sampled before the start of the ICU shift using a modified glove-juice method. Standard microbiological techniques and a series of polymerase chain reaction (PCR) assays were used to identify and characterize the bacteria. All the isolates were tested for resistance against a specific panel of antibiotics using the disk diffusion method. Proportions of bacterial species and their antimicrobial-susceptibility profiles were calculated. Results: At screening, all the veterinary students (n = 62) carried at least one of the ESKAPE organisms on their hands. Escherichia coli was the most isolated organism (76%, 47/62), followed by P. aeruginosa (48%, 30/62), A. baumannii (47%, 29/62), E. faecium (35%, 22/62), K. pneumoniae (27%, 17/62), and S. aureus (24%, 15/62). A reduced proportion of isolates were recovered from the samples, E. coli (26%, 12/47), E. faecium (23%, 5/22), P. aeruginosa (43%, 13/30), A. baumannii (24%,7/29), K. pneumoniae (41%, 7/17), and S. aureus (20%, 3/15). Most of the organisms showed a high proportion of resistance to at least one antibiotic. Multidrug resistance was reported among just over half (56%, 5/9) of E. coli, 40% (2/5) of E. faecium, 100% (13/13) of P. aeruginosa, and 33% (1/3) of S. aureus isolates. Conclusion: Students working in the ICU carry several organisms belonging to the ESKAPE group of organisms before contact with patients. Moreover, MDR resistance was common among this group of organisms. The findings of the present study underscore the importance of infection prevention and control (IPC) strategies to help reduce the likelihood of the spread of these organisms to personnel, owners, family members, and patients. [ABSTRACT FROM AUTHOR]

An outbreak of OXA-23-producing carbapenem-resistant Acinetobacter baumannii amongst ICU-patients with COVID-19 likely occurred by transmission through inanimate surfaces, potentially facilitated by a contaminated positioning pillow shared between patients. Subsequent rapid spread may have been caused by exposure to respiratory secretions contaminating healthcare worker's gloves and gowns during prone positioning. [ABSTRACT FROM AUTHOR]

Phage therapy is gaining increasing interest in the fight against critically antibiotic-resistant nosocomial pathogens. However, the narrow host range of bacteriophages hampers the development of broadly effective phage therapeutics and demands precision approaches. Here, we combine large-scale phylogeographic analysis with high-throughput phage typing to guide the development of precision phage cocktails targeting carbapenem-resistant Acinetobacter baumannii , a top-priority pathogen. Our analysis reveals that a few strain types dominate infections in each world region, with their geographical distribution remaining stable within 6 years. As we demonstrate in Eastern Europe, this spatiotemporal distribution enables preemptive preparation of region-specific phage collections that target most local infections. Finally, we showcase the efficacy of phage cocktails against prevalent strain types using in vitro and animal infection models. Ultimately, genomic surveillance identifies patients benefiting from the same phages across geographical scales, thus providing a scalable framework for precision phage therapy. [Display omitted] • A few CRAB types dominate infections in individual world regions • Phylogeography reveals stable strain composition for countries over 6 years • Spatiotemporal distribution informs the development of region-specific phage collections • Phage cocktails are effective against the most prevalent strain types in Eastern Europe By mapping the genetic diversity and geographic distribution of carbapenem-resistant Acinetobacter baumannii , bacteriophage cocktails were developed and designed to treat the maximum number of patients within a specific geographic region. [ABSTRACT FROM AUTHOR]

Background: Venereal syphilis in humans is caused by Trepenoma pallidum subspp. pallidum. A study has shown that 30,302 individuals in Thailand had syphilis in 2020, with a male-to-female ratio of 1:0.8 and the highest incidence rate at ages between fifteen and twenty-four. Methods: This research aimed to develop a loop-mediated isothermal amplification assay using gold nanoparticles (LAMP-AuNPs). Analytical sensitivity, diagnostic specificity, accuracy, and predictive values for each technique are provided. Results: The diagnosis sensitivities of polymerase chain reaction using agarose gel electrophoresis (PCR-AGE), loop-mediated isothermal amplification assay using agarose gel electrophoresis (LAMP-AGE), and LAMP-AuNPs were 116 ng/µL, 11.6 ng/µL, and 11.6 ng/µL, respectively. We evaluated the analytical specificity using PCR and a LAMP-based assay, and there was no cross-reactivity to Leptospira interrogans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, human immunodeficiency virus (HIV), and healthy humans. After analyzing 400 serum samples of patients suspected of syphilis, the LAMP-AGE and LAMP-AuNPs assays displayed 100% diagnostic sensitivity scores, 91% diagnostic specificity scores, 95.5% accuracy rates, 100% positive predictive values (PPVs), and 91% negative predictive values (NPVs), the positive likelihood ratio (LR+) was 11.11, while the negative likelihood ratio (LR−) was 0. Conversely, for PCR assays displayed 100% diagnostic sensitivity scores, 94.5% diagnostic specificity scores, 97.25% accuracy rates, 100% PPVs, and 94.5% NPVs, LR+ was 18.18, and LR− was 0. Conclusions: The LAMP-AuNPs technique demonstrates rapidity, affordability, and convenience, rendering it well-suited for point-of-care applications in the diagnosis, prevention, and management of pathogenic infections. [ABSTRACT FROM AUTHOR]

Background: The rise of multi-drug-resistant Gram-negative bacteria necessitates the development of new antimicrobial agents. Cefiderocol shows promising activity by exploiting bacterial iron transport systems to penetrate the outer membranes of resistant pathogens. Objectives: This study evaluates the efficacy of cefiderocol testing methods and trailing effect impact using a ComASP® Cefiderocol panel, disk diffusion (DD), and MIC test strips (MTS) compared to iron-depleted broth microdilution (ID-BMD). Methods: A total of 131 Gram-negative strains from clinical samples was tested by commercial methods and the gold standard. Results were interpreted as per 2024 and 2023 EUCAST guidelines. Results: ID-BMD revealed high cefiderocol susceptibility among Enterobacterales and Pseudomonas aeruginosa, with one Klebsiella pneumoniae isolate being resistant. Acinetobacter baumannii exhibited higher MIC values, particularly considering trailing effects that complicated MIC readings. ComASP® showed 97% categorical agreement (CA) and 66% essential agreement (EA) with ID-BMD for Enterobacterales but failed to detect the resistant K. pneumoniae. DD tests demonstrated variable CA (72% or 93%), and 38% or 34% of strains within the ATU according to EUCAST Breakpoint Tables v13.0 and 14.0, respectively, with major errors only. MTS for P. aeruginosa had 100% CA but 44% EA, and often underestimated MIC values. Conclusions: The study emphasizes the need for standardized criteria to address trailing effects and ATU and highlights the discrepancies between testing methods. While cefiderocol resistance remains rare, accurate susceptibility testing is crucial for its effective clinical use. The findings suggest that current commercial tests have limitations, necessitating careful interpretation and potential supplementary testing to guide appropriate antibiotic therapy. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Acinetobacter baumannii denotes a significant menace to public health, and it mandates an urgent development of new effective medications. Here, we aimed to estimate the efficiency of the zinc oxide nanoparticles (ZnO NP) biosynthesized from Arthrospira maxima (Spirulina) both in vitro and in vivo. Carbapenem-resistant A. baumannii isolates were collected, identified, tested for their antibiotic susceptibility, and then subjected to PCR to detect carbapenemase-producing genes. The most predominant carbapenemase resistance gene was blaKPC. The biosynthesized ZnO NP were characterized using UV, FTIR, XRD, SEM, and TEM. The prepared ZnO NP was then tested against A. baumannii isolates to determine the minimum inhibitory concentration (MIC), which ranged from 250 to 1000 μg/ml. Burn wound was persuaded in twenty rats and inoculated with carbapenem-resistant A. baumannii isolate. Rats were allocated into four groups: a negative control group, a positive control group treated with topical 0.9% saline, a test treatment group that received topical ZnO NP, and a standard treatment group. All groups received treatment for 15 consecutive days and then euthanized. Skin samples were harvested and then subjected to histopathological and immunochemical investigations. ZnO NP revealed a comparable antibacterial activity to colistin as it revealed a lower level of fibrosis, mature surface epithelization with keratinization, and restoration of the normal skin architecture. In addition, it significantly decreased the immunoreactivity of the studied inflammatory markers. Thus, ZnO NP synthesized by A. maxima could be considered a promising, safe, and biocompatible alternative to traditional antibiotics in the therapy of carbapenem-resistant A. baumannii infections. [ABSTRACT FROM AUTHOR]

Background The treatment of carbapenem-resistant Acinetobacter baumannii / calcoaceticus complex (CRAB) presents significant treatment challenges. Methods We report the case of a 42-year-old woman with CRAB meningitis who experienced persistently positive cerebrospinal fluid (CSF) cultures for 13 days despite treatment with high-dose ampicillin-sulbactam and cefiderocol. On day 13, she was transitioned to sulbactam-durlobactam and meropenem; 4 subsequent CSF cultures remained negative. After 14 days of sulbactam-durlobactam, she was cured of infection. Whole genome sequencing investigations identified putative mechanisms that contributed to the reduced cefiderocol susceptibility observed during cefiderocol therapy. Blood and CSF samples were collected pre-dose and 3-hours post initiation of a sulbactam-durlobactam infusion. Results The CRAB isolate belonged to sequence type 2. An acquired bla OXA-23 and an intrinsic bla OXA-51-like (ie, bla OXA-66) carbapenemase gene were identified. The paradoxical effect (ie, no growth at lower cefiderocol dilutions but growth at higher dilutions) was observed by broth microdilution after 8 days of cefiderocol exposure but not by disk diffusion. Potential markers of resistance to cefiderocol included mutations in the start codon of piuA and piuC iron transport genes and an A515V substitution in PBP3, the primary target of cefiderocol. Sulbactam and durlobactam were detected in CSF at both timepoints, indicating CSF penetration. Conclusions This case describes successful treatment of refractory CRAB meningitis with the administration of sulbactam-durlobactam and meropenem and highlights the need to be cognizant of the paradoxical effect that can be observed with broth microdilution testing of CRAB isolates with cefiderocol. [ABSTRACT FROM AUTHOR]

Background: Extensively drug-resistant Acinetobacter baumannii (XDRAB) has become a significant pathogen in hospital environments, particularly in intensive care units (ICUs). XDRAB's resistance to conventional antimicrobial treatments and ability to survive on various surfaces pose a substantial threat to patient health, often resulting in severe infections such as ventilator-associated pneumonia (VAP) and bloodstream infections (BSI). Methods: We retrospectively analyzed clinical data from 559 patients with XDRAB infections admitted to Jinhua Central Hospital between January 2021 and December 2023. Patients were randomly divided into a training set (391 cases) and a testing set (168 cases). Variables were selected using Lasso regression and logistic regression analysis, and a predictive model was constructed and validated internally and externally. Model performance and clinical utility were evaluated using the Hosmer-Lemeshow test, C-index, ROC curve, decision curve analysis (DCA), and clinical impact curve (CIC). Results: Lasso regression analysis was used to screen 35 variables, selecting features through 10-fold cross-validation. We chose lambda.1se=0.03450 (log (lambda.1se)=-3.367), including 10 non-zero coefficient features. These features were then included in a multivariate logistic regression analysis, identifying 8 independent risk factors for XDRAB infection: ICU stay of 1-7 days (OR=3.970, 95%CI=1.586-9.937), ICU stay >7 days (OR=12.316, 95%CI=5.661-26.793), hypoproteinemia (OR=3.249, 95%CI=1.679-6.291), glucocorticoid use (OR=2.371, 95%CI=1.231-4.564), urinary catheterization (OR=2.148, 95% CI=1.120-4.120), mechanical ventilation (OR=2.737, 95%CI=1.367-5.482), diabetes mellitus (OR=2.435, 95%CI=1.050-5.646), carbapenem use (OR=6.649, 95%CI=2.321-19.048), and β-lactamase inhibitor use (OR=4.146, 95%CI=2.145-8.014). These 8 factors were used to construct a predictive model visualized through a nomogram. The model validation showed a Cindex of 0.932 for the training set and 0.929 for the testing set, with a Hosmer-Lemeshow test p-value of 0.47, indicating good calibration. Furthermore, the DCA curve demonstrated good clinical decision-making performance, and the CIC curve confirmed the model's reliable clinical impact. Conclusion: Regression analysis identified ICU stay duration, hypoproteinemia, glucocorticoid use, urinary catheterization, mechanical ventilation, diabetes mellitus, carbapenem use, and β-lactamase inhibitor use as independent risk factors for XDRAB infection. The corresponding predictive model demonstrated high accuracy and stability. [ABSTRACT FROM AUTHOR]

Introduction: Gram-negative bacteremia is a life-threatening infection with high morbidity and mortality. Its incidence is rising worldwide, and treatment has become more challenging due to emerging bacterial resistance. Little data is available on the burden and outcome of such infections in Lebanon. Methods: We conducted this retrospective study in four Lebanese hospitals. Data on medical conditions and demographics of 2400 patients diagnosed with a bloodstream infection based on a positive blood culture were collected between January 2014 and December 2020. Results: Most bacteremias were caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii, with the more resistant organisms being hospital-acquired. Third-generation cephalosporin and quinolone resistance was steady throughout the study, but carbapenem resistance increased. Mortality with such infections is high, but carbapenem resistance or infection with Pseudomonas or Acinetobacter species were significant risk factors for poor outcomes. Conclusion: This is the first multi-center study from Lebanon on gram-negative bacteremia, resistance patterns, and factors associated with a poor outcome. More surveillance is needed to provide data to guide empirical treatment for bacteremia in Lebanon. [ABSTRACT FROM AUTHOR]

Background and objectives: Of the genes conferring resistance to carbapenems in Acinetobacter baumannii, the blaOXA−23 gene is the most widely found across the world. The gene carrying blaOXA−23 transposons in A. baumannii isolates of global clones GC1 and GC2 is found worldwide. Here, we examined whether transposons play a role in the dissemination of the blaOXA−23 in globally distributed clones, GC1 and GC2 A. baumannii isolates from Iraq. Materials and methods: The 119 non-repetitive A. baumannii isolates including 94 recovered from clinical specimens and 25 isolates from hospital environment between September 2021 and April 2022 from different medical centers located at various regions in Baghdad, Iraq. The global clones (GC) and the genes encoding carbapenem resistance, including blaOXA−23, blaOXA−24, and blaOXA−58 were identified using multiplex PCR assays. Antibiotic susceptibility testing was performed by the Kirby-Bauer disk diffusion susceptibility method. The transposons carrying blaOXA−23 were examined using PCR mapping. In cases when carbapenem susceptible A. baumannii isolates were found, they were subjected to E test, full length sequencing of blaOXA−Ab (blaOXA−51−like) and Institut Pasteur multi-locus sequence typing scheme. Results: All but two isolates (92 clinical and 25 environmental) were identified carbapenem-resistant A. baumannii (CRAB). Of 117 CRAB isolates, 20 belong to GC1, 19 contained blaOXA−23; of them, 17 isolates harbored the blaOXA−23 located on Tn2006. Among the 46 CRAB belonging to GC2, 39 contained blaOXA−23; of them, 34 carried the blaOXA−23 located on Tn2006. The remaining GC1 and GC2 isolates, one GC1 as well as one GC2 isolate, were susceptible to imipenem, doripenem, and meropenem and considered carbapenem-susceptible A. baumannii (CSAB). Full-length sequencing of the blaOXA−Ab and MLST for the two CSAB isolates belonging to GC1 and GC2 confirmed that the GC1 isolate belongs to ST 623 and contained an allele that encodes an blaOXA−69 variant of the blaOXA−Ab while the GC2 belong to ST2 and carried an blaOXA−66 variant. Conclusion: This study provides evidence for the dissemination of blaOXA−23 on the Tn2006 in CRAB isolates in Baghdad, Iraq. It appears that this transposon is widespread in GC1 and 2 isolates as in the other parts of the world. Interestingly, one GC1 and one GC2 isolate from Iraq were found to be susceptible to carbapenem while the isolates belonging to GC1 and GC2 have so far rarely been found to be susceptible to carbapenem globally. [ABSTRACT FROM AUTHOR]

Background: Inorganic polyphosphate (polyP)-targeted polyphosphate kinase 1 (PPK1) has attracted much attention by virtue of its importance in bacterial pathogenicity and persistence, as well as its exclusive presence in microorganisms. However, only very few drugs have been found to be efficacious in inhibiting the Acinetobacter baumannii (A. baumannii) PPK1 protein. Results: In this study, we identified Scutellarein (Scu), a potent PPK1 inhibitor that could significantly influence PPK1-regulated motility, biofilm formation, and bacterial persistence, which was further validated by the results of transcriptome analysis. Mechanistic explorations revealed that Scu achieved its enzyme inhibitory activity predominantly through direct engagement with the active center of PPK1. Moreover, the survival rate of Galleria mellonella larvae was increased by about 35% with 20 mg/kg of Scu treatment. The remarkable therapeutic benefits of Scu were also observed in the mouse pneumonia model, shown mainly by reduced bacterial colonization, pathological lesions, and inflammatory factors. Conclusion: Our results revealed that Scu could attenuate the pathogenicity and persistence of A. baumannii by interfering with its important kinase PPK1. [ABSTRACT FROM AUTHOR]

This review discusses the eco-friendly and cost-effective biosynthesis of gold nanoparticles (AuNPs) in viable microorganisms, focusing on microbes-mediated AuNP biosynthesis. This process suits agricultural, environmental, and biomedical applications, offering renewable, eco-friendly, non-toxic, sustainable, and time-efficient methods. Microorganisms are increasingly used in green technology, nanotechnology, and RNAi technology, but several microorganisms have not been fully identified and characterized. Bio-nanotechnology offers eco-friendly and sustainable solutions for nanomedicine, with microbe-mediated nanoparticle biosynthesis producing AuNPs with anti-oxidation activity, stability, and biocompatibility. Ultrasmall AuNPs offer rapid distribution, renal clearance, and enhanced permeability in biomedical applications. The review explores nano-size dependent biosynthesis of AuNPs by bacteria, fungi, and viruses revealing their non-toxic, non-genotoxic, and non-oxidative properties on human cells. AuNPs with varying sizes and shapes, from nitrate reductase enzymes, have shown potential as a promising nano-catalyst. The synthesized AuNPs, with negative charge capping molecules, have demonstrated antibacterial activity against drug-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii strains, and were non-toxic to Vero cell lines, indicating potential antibiotic resistance treatments. A green chemical method for the biosynthesis of AuNPs using reducing chloroauric acid and Rhizopus oryzae protein extract has been described, demonstrating excellent stability and strong catalytic activity. AuNPs are eco-friendly, non-toxic, and time-efficient, making them ideal for biomedical applications due to their antioxidant, antidiabetic, and antibacterial properties. In addition to the biomedical application, the review also highlights the role of microbially synthesized AuNPs in sustainable management of plant diseases, and environmental bioremediation. [ABSTRACT FROM AUTHOR]

This study uncovers the molecular processes governing the adaptive evolution of multidrug-resistant (MDR) pathogens without antibiotic pressure. Genomic analysis of MDR Acinetobacter baumannii cells cultured for 8000 generations under starvation conditions (EAB1) or nutrient-rich conditions (EAB2) revealed significant genomic changes, primarily by insertion sequence (IS)-mediated insertions and deletions. Only two Acinetobacter-specific prophage-related deletions and translocations were observed in the EAB1 strain. Both evolved strains exhibited higher virulence in mouse infection studies, each with different modes of action. The EAB1 strain displayed a heightened ability to cross the epithelial barrier of human lung tissue, evade the immune system, and spread to lung tissues, ultimately resulting in cellular mortality. In contrast, the EAB2 strain strongly attached to epithelial cells, leading to increased synthesis of proinflammatory cytokines and chemokines. The genomic alterations and increased virulence observed in evolved strains during short-term evolution underscore the need for caution when handling these pathogens, as these risks persist even without antibiotic exposure. Multidrug-resistant Acinetobacter baumanniicultured for 8000 generations under either starvation or nutrient-rich conditions reveals significant genomic alterations and changes in virulence, primarily driven by insertion sequences and prophages. [ABSTRACT FROM AUTHOR]