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The self‐organization of microbes into biofilms provides multiple benefits including tolerance to mechanical stress and resistance to immune defences and antibiotics. Coupled to a compromised mucociliary function, these traits have dire consequences in cystic fibrosis patients – persistent infections are the main reason for morbidity and mortality. Thereby, disease progression is associated with universal colonization by Pseudomonas aeruginosa, which selects for a slimy phenotype to adapt to the lung microenvironment. Recognizing this, drug‐delivery vehicles that break down the mucoid extracellular matrix made of alginate are designed to enable better penetration and biofilm dispersion. In parallel, a protective layer responds to the proteolytic activity of the pathogen and thus controls drug availability. To realize this architecture, silica nanoparticles are loaded with imipenem, and then coated with elastin and alginate lyase in a layer‐by‐layer fashion using ultrasound. The nanoscale formulations eradicate up to 80% of the total biomass and reduce the bacterial viability in biofilms by 3 logs, considerably outperforming the bulk antibiotic in vitro, whereby the effects are correlated to changes in the viscoelasticity. Furthermore, the stimuli‐responsive nanocarriers are safe and effective in animal models of P. aeruginosa infection, presenting a considerable therapeutic promise in the challenging context of lung diseases. [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]

Introduction: Bone and joint infections (BJIs) caused by multidrug-resistant bacteria are becoming more frequent. However, data on the use of novel β-lactam/β-lactamase inhibitors, such as imipenem/cilastatin/relebactam (I-R) and meropenem/vaborbactam (MVB), to treat BJIs is lacking. Furthermore, prolonged infusions of these β-lactams should theoretically optimize pharmacokinetic/pharmacodynamics target in these indications, but there are currently no reports on this type of infusions, especially in the setting of BJI. Case Presentation: We report a case of a vertebral osteomyelitis caused by carbapenem-resistant Enterobacter cloacae successfully treated with extended-infusion of I-R (1.25 g q6h over 2 h), then with continuous infusion of MVB (2 g q4h as over 4 h). Therapeutic drug monitoring confirmed that extended-infusion of I-R and continuous infusion of MVB achieved serum concentrations up to 12 mg/L of imipenem and 19 mg/L of meropenem, respectively. Conclusion: The favourable outcome of this patient treated for a vertebral osteomyelitis caused by carbapenem-resistant E. cloacae suggest that extended- and continuous infusions of I-R and MVB, are promising regimens for treatment of BJIs caused by carbapenem-resistant Enterobacterales. [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus complex is a group of rapidly growing non-tuberculous mycobacteria (NTM), increasingly emerging as opportunistic pathogens. Current treatment options for these microorganisms are limited and associated with a high rate of treatment failure, toxicity and recurrence. In search of new therapeutic strategies, interest has grown in dual β-lactam (DBL) therapy, as research recently discovered that M. abscessus cell wall synthesis is mainly regulated by two types of enzymes (d , d- transpeptidases and l , d- transpeptidases) differently susceptible to inhibition by distinct β-lactams. In vitro studies testing several DBL combinations have shown synergy in extracellular broth cultures as well as in the intracellular setting: cefoxitin/imipenem, ceftaroline/imipenem, ceftazidime/ceftaroline and ceftazidime/imipenem. The addition of specific β-lactamase inhibitors (BLIs) targeting M. abscessus β-lactamase did not significantly enhance the activity of DBL combinations. However, in vivo data are lacking. We reviewed the literature on DBL/DBL-BLI-based therapies for M. abscessus infections to raise greater attention on this promising yet overlooked treatment option and to guide future preclinical and clinical studies. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a bacterial pathogen of considerable significance in public health, capable of inducing a diverse range of infectious diseases. One of the most notorious mechanisms used by S. aureus to survive and colonize the site of infection is its ability to form biofilms. Diflunisal, a non-steroidal antiinflammatory drug (NSAID), is a known inhibitor of the Agr system in S. aureus, which is key in regulating biofilm formation. This study evaluated the effect of broad-spectrum antibiotics in combination with diflunisal on S. aureus biofilm density. Eight antibiotics were tested independently at different concentrations and in combination with diflunisal to assess their effect on S. aureus biofilm formation. When using the antibiotics alone and with diflunisal, a significant control effect on biofilm formation was observed (p < 0.05), irrespective of diflunisal presence, but did not achieve a complete biofilm growth inhibition. Over time, diflunisal influenced biofilm formation; however, such an effect was correlated with antibiotic concentration and exposure time. With amikacin treatments, biofilm density increased with extended exposure time. In the case of imipenem, doripenem, levofloxacin, and ciprofloxacin, lower doses and absence of diflunisal showed higher control over biofilm growth with longer exposure. However, in all cases, diflunisal did not significantly affect the treatment effect on biofilm formation. In the absence of antibiotics, diflunisal significantly reduced biofilm formation by 53.12% (p < 0.05). This study suggests that diflunisal could be a potential treatment to control S. aureus biofilms, but it does not enhance biofilm inhibition when combined with antibiotics. [ABSTRACT FROM AUTHOR]

This research aimed to analyze the volatile compounds emitted during the proliferation of Klebsiella pneumoniae (K. pneumoniae) in the laboratory setting using gas chromatography-ion mobility spectrometry (GC-IMS) and to investigate the potential of volatile metabolomics for detecting carbapenemase-producing strains of K. pneumoniae. The volatile metabolomics of K. pneumoniae were comprehensively analyzed using GC-IMS in tryptic soy broth (TSB) as the culture medium. Afterward, the growth stabilization period (T2) served as the primary time point for analysis, with the introduction of imipenem and carbapenemase inhibitors (avibactam sodium or EDTA) during the exponential growth phase (T0) to further investigate alterations in volatile molecules associated with K. pneumoniae. Standard strains were utilized as references, while clinical strains were employed for validation purposes. At T2, a total of 22 volatile organic compounds (VOCs) associated with K. pneumoniae were identified (3 VOCs found in both monomer and dimer forms). Significant differences in VOCs were observed between carbapenemase-negative and carbapenemase-positive strains, both standard and clinical, following the introduction of imipenem. Furthermore, the addition of avibactam sodium led to distinct changes in the VOC content of strains producing class A carbapenemase, while the addition of EDTA resulted in specific alterations in the volatile metabolic profiles of strains producing class B carbapenemase. GC-IMS demonstrated significant promise for analyzing bacterial volatile metabolomics, and its application in evaluating the volatolomics of K. pneumoniae may facilitate the timely detection of carbapenemase-producing strains. [ABSTRACT FROM AUTHOR]

Introduction: Antimicrobial susceptibility testing (AST) using broth microdilution (BMD) is usually the reference method to obtain accurate minimum inhibitory concentrations and optimally manage infections with resistant organisms. Several commercial dry BMD are available for AST in clinical laboratories. Materials and methods: Two commercial BMD panels for testing of multidrugresistant Gram-negative bacteria were compared: the Thermo Scientific™ Sensititre DKMGN and the Beckman Coulter NMDRM1, for 17 antimicrobial agents. Results: A total of 207 isolates were tested: three ATCC strains and one NCTC strain, six quality control strains from the Belgian National Antimicrobial Committee, and 197 clinical isolates, including carbapenem-resistant Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2023 breakpoints version 13.1 were used to assign susceptibility categories. Discussion: Overall, the categorical agreement (CA) and essential agreement (EA) were both above 90%, but several useful antibiotics for the treatment of multiresistant organisms showed CA and EA under 90%, that is, meropenem, imipenem, and colistin for Enterobacterales and meropenem and colistin for P. aeruginosa. For Enterobacterales, the NMDRM1 panel showed a significantly higher resistance rate for meropenem, imipenem, amikacin, and colistin. For carbapenems, the minimal inhibitory concentrations (MICs) were underestimated by the DKMGN panel, as already pointed out by a warning on the EUCAST website. To better assess carbapenem susceptibility in carbapenem-resistant organisms, the DKMGN panel now requires the use of a higher inoculum in the insert kit. However, for a given isolate whose susceptibility to carbapenems is not known, there is a risk of underestimating the MIC values. Our results show that colistin testing remains a challenge, highlighting the urgent need for the development of more accurate commercial methods. The use of a single commercial method cannot guarantee good precision in the determination of the MIC value for colistin. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing. [ABSTRACT FROM AUTHOR]

Objective To establish a ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay to quantify plasma imipenem (IMP) in patients with Augmented Renal Clearance (ARC), and to investigate the pharmacokinetic characteristics of IMP in patients with ARC. Methods The plasma samples were treated with acetonitrile precipitated protein and analyzed by UPLC-MS/MS method with amoxicillin as the internal standard. ARC patients with IMP administration regimen of 1 g, intravenous drip, ARC patients at an interval of 8 h were screened, blood samples were collected at different times and plasma concentrations were detected, and pharmacokinetic parameters were calculated. Results Linear calibration curves of IMP were generated over the range of 0.40-200.00 µg/mL, and the precision, accuracy, matrix effect, method recovery and stabilityall met the requirements. The half-life of IMP in ARC patients was (0.97±0.06)h, the area under the drug curve (AUC) was (48.49±14.93)mg/(Lh), the apparent volume of distribution was (16.15±7.90) L, and the creatinine clearance rate was (18.30±5.70) L/h. The peak con- centration was (15.63±4.60) µg/mL. Conclusion This method has high accuracy and high sensitivity, and can be effectively applied to the detection of IMP concentration in plasma of ARC patients. The metabolic rate and clearance rate of IMP may change in ARC patients, which provides an important reference for clinical drug use. [ABSTRACT FROM AUTHOR]

Objectives We aimed to compare the stability of the newly developed β-lactams (cefiderocol) and β-lactam/β-lactamase inhibitor combinations (ceftazidime/avibactam, ceftolozane/tazobactam, aztreonam/avibactam, cefepime/taniborbactam, cefepime/zidebactam, imipenem/relebactam, meropenem/vaborbactam, meropenem/nacubactam and meropenem/xeruborbactam) against the most clinically relevant mechanisms of mutational and transferable β-lactam resistance in Pseudomonas aeruginosa. Methods We screened a collection of 61 P. aeruginosa PAO1 derivatives. Eighteen isolates displayed the most relevant mechanisms of mutational resistance to β-lactams. The other 43 constructs expressed transferable β-lactamases from genes cloned in pUCP-24. MICs were determined by reference broth microdilution. Results Cefiderocol and imipenem/relebactam exhibited excellent in vitro activity against all of the mutational resistance mechanisms studied. Aztreonam/avibactam, cefepime/taniborbactam, cefepime/zidebactam, meropenem/vaborbactam, meropenem/nacubactam and meropenem/xeruborbactam proved to be more vulnerable to mutational events, especially to overexpression of efflux operons. The agents exhibiting the widest spectrum of activity against transferable β-lactamases were aztreonam/avibactam and cefepime/zidebactam, followed by cefepime/taniborbactam, cefiderocol, meropenem/xeruborbactam and meropenem/nacubactam. However, some MBLs, particularly NDM enzymes, may affect their activity. Combined production of certain enzymes (e.g. NDM-1) with increased MexAB-OprM-mediated efflux and OprD deficiency results in resistance to almost all agents tested, including last options such as aztreonam/avibactam and cefiderocol. Conclusions Cefiderocol and new β-lactam/β-lactamase inhibitor combinations show promising and complementary in vitro activity against mutational and transferable P. aeruginosa β-lactam resistance. However, the combined effects of efflux pumps, OprD deficiency and efficient β-lactamases could still result in the loss of all therapeutic options. Resistance surveillance, judicious use of new agents and continued drug development efforts are encouraged. [ABSTRACT FROM AUTHOR]

Carbapenem-resistance in Enterobacter spp due to acquisition of mobile carbapenemases is of concern. An Enterobacter spp grew on ChromID CARBA medium and was positive for the mCIM carbapenemase detection assay. Susceptibility testing showed resistance to aztreonam and reduced susceptibility to imipenem. Conventional PCR using FRI primers detected a blaFRI gene. Whole genome sequencing reveled a new variant; blaFRI−12 was closest in sequence to blaFRI−5 differing by 13 amino acids and was found on a unique 110Kb IncR plasmid. Given the intrinsic nature of Enterobacter spp. to be carbapenem non-susceptible, blaFRI-types may be under reported globally. [ABSTRACT FROM AUTHOR]

We aimed to assess the accuracy of BD Phoenix for determining carbapenem susceptibility because we observed a decline in carbapenem susceptibility rate from the biannual cumulative data, after we transitioned to the BD Phoenix form Vitek 2 system. Between October 2021 and May 2022, we collected 82 non-duplicated Enterobacterales showing non-susceptible to at least one of the three carbapenems by BD Phoenix. We performed the broth microdilution (BMD) and disk diffusion (DD) according to the CLSI guideline. Compared to BMD, the categorical agreements for ertapenem (ERT), imipenem (IPM) and meropenem (MEPM) was 58.8%, 56.8% and 91.5% for BD Phoenix and it was 85.4%, 89.0%, and 97.6%, respectively, for DD (p value; 0.0001 for ERT and IPM , p value; 0.17 for MEPM). The major errors/minor errors for ERT, IPM, and MEPM were 14.0%/31.7%, 2.94%/40.7%, and 2.56%/6.10%, respectively for BD Phoenix, compared to 0%/14.6%, 0%/9.8%, and 0%/2.5%, for DD. While errors in the BD Phoenix showed tendency towards resistance, those in DD displayed no tendency towards either resistance or susceptibility. With DD, 21 out of the 27 isolates showing susceptible/intermediate/susceptible pattern (ERT/IPM/MEPM) and 13 out of the 16 isolates showing intermediate/susceptible/susceptible pattern (ERT/IPM/MEPM), were correctly categorized by DD. However, for 22 isolates showing resistant/susceptible/susceptible pattern (ERT/IPM/MEPM), only 13 isolates were correctly categorized by DD. In conclusion, to mitigate the risk of overcalling carbapenem non-susceptibility with BD Phoenix, it will be helpful to perform a complementary test using DD and to provide comments on the DD results to clinicians. [ABSTRACT FROM AUTHOR]

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography–mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography–mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods. [ABSTRACT FROM AUTHOR]

Introduction: Our work aims at establishing a proof-of-concept for a method that allows the early prediction of the bactericidal and bacteriostatic effects of antibiotics on bacteria using scanning electron microscopy (SEM) as compared to traditional culture-based methods. Methods: We tested these effects using Imipenem (bactericidal) and Doxycycline (bacteriostatic) with several strains of sensitive and resistant Escherichia coli. We developed a SEM-based predictive score based on three main criteria: Bacterial Density, Morphology/Ultrastructure, and Viability. We determined the results for each of these criteria using SEM micrographs taken with the TM4000Plus II-Tabletop-SEM (Hitachi, Japan) following an optimized, rapid, and automated acquisition and analysis protocol. We compared our method with the traditional culture colony counting gold standard method and classic definitions of the two effects. Results: Our method revealed total agreement with the CFU method and classic definition by visualizing the effect of the antibiotic at 60 minutes and 120 minutes using SEM. Discussion: This early prediction allows a rapid and early identification of the bactericidal and bacteriostatic effects as compared to culture that would take a minimum of 18 hours. This has several future applications in the development of SEM-automated assays coupled to machine learning models that identify the antibiotic effect and facilitate determination of bacterial susceptibility. [ABSTRACT FROM AUTHOR]

Introduction: A chronic inflammation of the middle ear and mastoid cavity that lasts more than two weeks is known as chronic suppurative otitis media (CSOM). A common organism that causes CSOM is pseudomonas aeruginosa. Although carbapenems are among the best medicines for treating Pseudomonas infections, the development of metallo-ß-lactamases strains is frequently linked to carbapenem resistance. Finding strains that produce MBLs can help ensure that patients receive the best care possible to stop the development of resistance. Finding the imipenem-resistant Pseudomonas aeruginosa carrying the metallo-ß-lactamase (MBL) geneblaIMP-1 is the primary goal of the research. Aim and Objective: To study the Molecular Characterization of Metallo-Beta Lactamase Gene blaIMP-1 in Imipenem Resistant Pseudomonas aeruginosa isolates from Patients of Chronic Suppurative Otitis Media. Material and Methods: This was a cross sectional study carried out in the Department of Microbiology and ENT Department for a period of 1 year i.e, May 2023 to May 2024. A total of 200 patients clinically suspected cases for CSOM was studied. Swabs taken from discharging ears were sent for Gram’s staining, culture and antibiotic sensitivity test as per the latest CLSI guidelines 2023. The DNA was extracted by using Qiagen DNA Extraction kit and blaIMP-1 gene for Pseudomonas aeruginosa isolates was detected by conventional PCR. Results: In the present study the number of cases clinically diagnosed of having CSOM were 200, out of which 70 (35%) was found to be culture positive for CSOM infection. Males were 44 (62.8%) as compared to that of female 26 (37.1%), the age group of 0-10 years followed by 11-20 years were being affected the most and the least number of cases was seen in the age group above 51 years. The side of the ear affected was almost in equal distribution, with the left ear being (51.4%) and the right ear being (40%) while (8.5%) were bilateral. In our study it was observed that the maximum number of cases was found in Gram negative isolates (98.5%) as compared to the Gram positive isolates (14.2%). It was also observed that 62 isolates (88.5%) samples showed growth of single isolates while 8 (11.4%) were mixed isolates. Pseudomonas aeruginosa being the most common isolate with 42.8% followed by Klebsiella sp. with 21.4% and among gram positive isolates Staphylococcus aureus was 11.4% and Streptococcus pneumonia (2.8%) being the least observed. The sensitivity observed in P. aeruginosa for Colistin was (97.1%), Piperacillin‑tazobactam (78.5%), Amikacin (82.8%), and cefepime (78.5%) were found to be the most effective Antibiotics. The resistance to ciprofloxacin was (56.6%), Levofloxacin (50%), Piperacillin(46.6%), Gentamicin(37.1%), Imipenem (31.4%), Tobramycin(31.4%), Ceftazidime (31.4%) and Gentamycin (37.1%). The blaIMP-1 gene was detected in 14 (20%) of the isolates of Pseudomonas aeruginosa Conclusion: Pseudomonas aeruginosa was the most frequently isolated strain in the current investigation, and the most effective antibiotics were cefepime, amikacin, piperacillin-tazobactam, and colonistin, ciprofloxacin and levofloxacin were the least effective. The Kanpur region (%) is seeing an increase in P. aeruginosa isolate resistance to imipenem as a result of MBL enzymes. Understanding the CSOM etiological agents and their antibiogram is crucial for effective treatment and prevention of antimicrobial resistance as well as clinical consequences. [ABSTRACT FROM AUTHOR]

Background β-lactam antibiotics, which inhibit penicillin-binding protein 3 (PBP3) that is required for cell division, play a key role in treating P. aeruginosa infections. Some sequence variations in PBP3 have been associated with β-lactam resistance but the effects of variations on antibiotic susceptibility and on cell division have not been quantified. Antibiotic efflux can also reduce susceptibility. Objectives To quantify the effects of PBP3 variations on β-lactam susceptibility and cell morphology in P. aeruginosa. Methods Nineteen PBP3 variants were expressed from a plasmid in the reference strain P. aeruginosa PAO1 and genome engineering was used to construct five mutants expressing PBP3 variants from the chromosome. The effects of the variations on β-lactam minimum inhibitory concentration (MIC) and cell morphology were measured. Results Some PBP3 variations reduced susceptibility to a variety of β-lactam antibiotics including meropenem, ceftazidime, cefepime and ticarcillin with different variations affecting different antibiotics. None of the tested variations reduced susceptibility to imipenem or piperacillin. Antibiotic susceptibility was further reduced when PBP3 variants were expressed in mutant bacteria overexpressing the MexAB-OprM efflux pump, with some variations conferring clinical levels of resistance. Some PBP3 variations, and sub-MIC levels of β-lactams, reduced bacterial growth rates and inhibited cell division, causing elongated cells. Conclusions PBP3 variations in P. aeruginosa can increase the MIC of multiple β-lactam antibiotics, although not imipenem or piperacillin. PBP3 variations, or the presence of sub-lethal levels of β-lactams, result in elongated cells indicating that variations reduce the activity of PBP3 and may reduce bacterial fitness. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate literature from a 12-year period (2010–2021) on the antimicrobial resistance profile of Pseudomonas aeruginosa from the Arabian Gulf countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates). Methods: An electronic literature search was conducted for articles on antimicrobial resistance in P. aeruginosa and associated phenotypes, covering the period of 1st January 2010 to 1st December 2021. Results: Antimicrobial resistance in the Arabian Gulf was highest to meropenem (10.3–45.7%) and lowest to colistin (0.0–0.8%), among the agents tested. Annual data showed that ceftazidime resistance (Kuwait), piperacillin-tazobactam non-susceptibility (Qatar), and aztreonam, imipenem, and meropenem resistance (Saudi Arabia) increased by 12–17%. Multiple mechanisms of carbapenem resistance were identified and multiple clones were detected, including high-risk clones such as ST235. The most common carbapenemases detected were the VIM-type metallo-β-lactamases. Conclusions: Among P. aeruginosa in the Arabian Gulf countries, resistance to meropenem was higher than to the other agents tested, and meropenem resistance increased in Saudi Arabia during the study period. Resistance to colistin, a classic antibiotic used to treat Pseudomonas spp. infections, remained low. The VIM-type β-lactamase genes were dominant. We recommend local and regional antimicrobial resistance surveillance programs to detect the emergence of resistance genes and to monitor antimicrobial resistance trends in P. aeruginosa. [ABSTRACT FROM AUTHOR]

Abstract 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.

Probiotics have emerged as agents that improve a wide range of conditions and provide essential ingredients for potential health benefits. Probiotics exhibit a diverse array of effects by engaging in [...]

Abstract Background Sepsis is a life-threatening organ dysfunction caused by an excessive host response to infection, manifested by elevated levels of inflammatory cytokines. At present, the use of hemoperfusion to remove inflammatory cytokines from the bloodstream has been expanding. Meanwhile, the pharmacokinetics and pharmacodynamics characteristics of antibiotics in critically ill patients may be impacted by hemoperfusion. Case presentation The patient was a 69-year-old male with poorly controlled type 2 diabetes. When admitted to the ICU, Multiple Organ Dysfunction Syndrome (MODS) appeared within 48 h, and he was suspected of septic shock due to acute granulocytopenia and significantly increased procalcitonin. Broad-spectrum antibiotics imipenem was administered according to Sepsis 3.0 bundle and hemoperfusion lasting 4 h with a neutron-macroporous resin device (HA-380, Jafron, China) five times was conducted to lower the extremely high value of serum inflammatory factors. Blood samples were collected to measure imipenem plasma concentration to investigate the effect of hemoperfusion quantitatively. This study showed that 4 h of hemoperfusion had a good adsorption ability on inflammatory factors and could remove about 75.2% of imipenem. Conclusions This case demonstrated the high adsorption capacity of hemoperfusion on imipenem in critically ill patients. It implies a timely imipenem supplement is required, especially before hemoperfusion.

ABSTRACT: Objectives: The main aim of this study was to evaluate the antibiofilm activity of cefiderocol alone and in combination with imipenem vs. sessile cells of Pseudomonas aeruginosa, assessing a potential synergistic bactericidal effect. Methods: Ten P. aeruginosa clinical isolates from infected implants and bloodstream were included in the study. Cefiderocol was tested alone and in combination with imipenem on 24-h-old P. aeruginosa biofilm formed on porous glass beads. For each antibiotic formulation, minimum bactericidal biofilm concentration (MBBC), defined as the lowest concentration that determined a reduction of at least 3 log10 CFU/mL compared with the untreated control, was evaluated. Scanning electron microscopy (SEM) was used to investigate the biofilm of P. aeruginosa treated with cefiderocol, imipenem, or their combination. Results: Cefiderocol and imipenem were tested alone on P. aeruginosa biofilm and a reasonable reduction in the number of viable cells was observed, especially at high drug concentrations tested. The synergistic effect of cefiderocol in combination with imipenem was evaluated for five selected isolates. Cotreatment with the two drugs led to a remarkable reduction of cell viability by resulting in synergistic bactericidal activity in all tested strains and in synergistic eradicating activity in only one isolate. SEM analysis revealed that, in cefiderocol-treated biofilm, bacterial cells became more elongated than in the untreated control, forming filaments in which bacterial division seems to be inhibited. Conclusions: Cefiderocol exhibited an encouraging antibiofilm activity against tested strains, representing a valid option for the treatment of P. aeruginosa biofilm-associated infections, especially when administered in combination with imipenem.

Background: Sepsis is a life-threatening organ dysfunction caused by an excessive host response to infection, manifested by elevated levels of inflammatory cytokines. At present, the use of hemoperfusion to remove inflammatory cytokines from the bloodstream has been expanding. Meanwhile, the pharmacokinetics and pharmacodynamics characteristics of antibiotics in critically ill patients may be impacted by hemoperfusion. Case presentation: The patient was a 69-year-old male with poorly controlled type 2 diabetes. When admitted to the ICU, Multiple Organ Dysfunction Syndrome (MODS) appeared within 48 h, and he was suspected of septic shock due to acute granulocytopenia and significantly increased procalcitonin. Broad-spectrum antibiotics imipenem was administered according to Sepsis 3.0 bundle and hemoperfusion lasting 4 h with a neutron-macroporous resin device (HA-380, Jafron, China) five times was conducted to lower the extremely high value of serum inflammatory factors. Blood samples were collected to measure imipenem plasma concentration to investigate the effect of hemoperfusion quantitatively. This study showed that 4 h of hemoperfusion had a good adsorption ability on inflammatory factors and could remove about 75.2% of imipenem. Conclusions: This case demonstrated the high adsorption capacity of hemoperfusion on imipenem in critically ill patients. It implies a timely imipenem supplement is required, especially before hemoperfusion. [ABSTRACT FROM AUTHOR]

Infections caused by pathogenic Escherichia coli are a serious threat to human health, while conventional antibiotic susceptibility tests (AST) have a long turn-around time, and rapid antibiotic susceptibility methods are urgently needed to save lives in the clinic, reduce antibiotic misuse and prevent emergence of antibiotic-resistant bacteria. We optimized and validated the feasibility of a novel rapid AST based on SYBR Green I and Propidium Iodide (SGPI-AST) for E. coli drug susceptibility test. A total of 112 clinical isolates of E. coli were collected and four antibiotics (ceftriaxone, cefoxitin, imipenem, meropenem) were selected for testing. Bacterial survival rate of E. coli was remarkably linearly correlated with S value at different OD600 values. After optimizing the antibiotic concentrations, the sensitivity and specificity of SGPI-AST reached 100%/100%, 97.8%/100%, 100%/100% and 98.4%/99% for ceftriaxone, cefoxitin, imipenem and meropenem, respectively, and the corresponding concordances of the SGPI-AST with conventional AST were 1.000, 0.980, 1.000 and 0.979, respectively. The SGPI-AST can rapidly and accurately determine the susceptibility of E. coli clinical isolates to multiple antibiotics in 60 min, and has the potential to be applied to guide the precise selection of antibiotics for clinical management of infections caused by pathogenic E. coli. [ABSTRACT FROM AUTHOR]

This case report details the challenging management of a 45-year-old male construction worker who suffered severe multiple injuries after a fall and subsequent collision with cement mixers. The patient presented with extensive injuries, including amputation, fractures and internal bleeding, leading to a state known as the 'triangle of death'. Despite the initial grim prognosis, evidenced by an ISS score of 28 and a mortality risk coefficient of 89.56%, the patient was successfully resuscitated and managed through a multidisciplinary approach. This included damage control resuscitation, emergency vascular interventions and targeted temperature management for brain protection. The patient's recovery highlights the effectiveness of comprehensive trauma management and the critical role of coordinated care in severe multi-trauma cases. [ABSTRACT FROM AUTHOR]

Objectives: Antiviral therapy approaches have become significant strategies to combat antibiotic resistance. Metal ions, particularly iron, play crucial roles in metabolic activities and virulence of bacteria. Loading iron into siderophore molecules could potentially circumvent antimicrobial resistance. This study aimed to evaluate the antibiofilm and antimicrobial effects of deferoxamine (DFO), an iron chelator and natural siderophore, on antibiotic susceptibility in clinical methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Acinetobacter baumannii (CRAB) isolates. Materials and Methods: The in vitro antibacterial activity of DFO alone and in combination with vancomycin [VAN (30 μg)], amoxicillin (25 μg), colistin (10 μg), and imipenem (10 μg), was investigated against MRSA and CRAB isolates using the disk diffusion method. The spectrophotometric microplate method was used to detect the in vitro antibiofilm effect of DFO. Results: DFO exhibited a synergistic effect with VAN, amoxicillin, and colistin and significantly disrupted mature biofilm formation in MRSA and CRAB isolates. Notably, the antibiofilm effect of DFO was more pronounced in CRAB strains. Conclusion: These findings highlight the potential of DFO as an antibiofilm agent candidate and suggest that it can enhance the antibiotic susceptibility of certain microorganism species. [ABSTRACT FROM AUTHOR]

Sepsis is a systemic inflammatory response syndrome caused by the invasion of pathogenic microorganisms. Despite major advances in diagnosis and technology, morbidity and mortality remain high. The level of neutrophil extracellular traps (NETs) is closely associated with the progression and prognosis of sepsis, suggesting the regulation of NET formation as a new strategy in sepsis treatment. Owing to its pleiotropic effects, atorvastatin, a clinical lipid-lowering drug, affects various aspects of sepsis-related inflammation and immune responses. To align closely with clinical practice, we combined it with imipenem for the treatment of sepsis. In this study, we used a cecum ligation and puncture-induced lung injury mouse model and employed techniques including western blot, immunofluorescence, and enzyme-linked immunosorbent assay to measure the levels of NETs and other sepsis-related lung injury indicators. Our findings indicate that atorvastatin effectively inhibited the formation of NETs. When combined with imipenem, it significantly alleviated lung injury, reduced systemic inflammation, and improved the 7-day survival rate of septic mice. Additionally, we explored the inhibitory mechanism of atorvastatin on NET formation in vitro , revealing its potential action through the ERK/NOX2 pathway. Therefore, atorvastatin is a potential immunomodulatory agent that may offer new treatment strategies for patients with sepsis in clinical settings. [Display omitted] • Atorvastatin regulates the formation of neutrophil extracellular traps (NETs). • Atorvastatin inhibits NETs through the ERK/NOX2 signaling pathway. • Atorvastatin combined with imipenem alleviates sepsis-induced lung injury by inhibiting NETs. [ABSTRACT FROM AUTHOR]

The objective of the current study was to evaluate the interaction between Tunisian Thymus capitatus essential oil (EO) and cefotaxime against Extended-Spectrum Beta-lactamases (ESBLs) producing Klebsiella pneumoniae hospital strains. GC-MS revealed that the major component of EO was found to be carvacrol (69.28%). The EO exerts an advanced bactericidal effect against all strains. Synergy between EO and cefotaxime was obtained by combined disk diffusion and checkerboard techniques. Combined use of EO and cefotaxime reduced the MIC of imipenem by 8- to 128-fold for all strains (fractional inhibitory concentration index ˂ 0.5, synergy). The time kill curve assay confirmed the advanced activity of combinatory effects of EO and cefotaxime, with total reduce of bacterial number (CFU/mL) after 6 h of culture. Synergistic activity of the combination between EO and cefotaxime constitute an important strategy as therapeutical option to combat infections caused by ESBLs producing Klebsiella pneumoniae. [ABSTRACT FROM AUTHOR]

Background Elizabethkingia spp. are emerging as nosocomial pathogens causing various infections. These pathogens express resistance to a broad range of antibiotics, thus requiring antimicrobial combinations for coverage. However, possible antagonistic interactions between antibiotics have not been thoroughly explored. This study aimed to evaluate the effectiveness of antimicrobial combinations against Elizabethkingia infections, focusing on their impact on pathogenicity, including biofilm production and cell adhesion. Methods Double-disc diffusion, time–kill, and chequerboard assays were used for evaluating the combination effects of antibiotics against Elizabethkingia spp. We further examined the antagonistic effects of antibiotic combinations on biofilm formation and adherence to A549 human respiratory epithelial cells. Further validation of the antibiotic interactions and their implications was performed using ex vivo hamster precision-cut lung sections (PCLSs) to mimic in vivo conditions. Results Antagonistic effects were observed between cefoxitin, imipenem and amoxicillin/clavulanic acid in combination with vancomycin. The antagonism of imipenem toward vancomycin was specific to its effects on the genus Elizabethkingia. Imipenem further hampered the bactericidal effect of vancomycin and impaired its inhibition of biofilm formation and the adhesion of Elizabethkingia meningoseptica ATCC 13253 to human cells. In the ex vivo PCLS model, vancomycin exhibited dose-dependent bactericidal effects; however, the addition of imipenem also reduced the effect of vancomycin. Conclusions Imipenem reduced the bactericidal efficacy of vancomycin against Elizabethkingia spp. and compromised its capacity to inhibit biofilm formation, thereby enhancing bacterial adhesion. Clinicians should be aware of the potential issues with the use of these antibiotic combinations when treating Elizabethkingia infections. [ABSTRACT FROM AUTHOR]

Urinary tract infections (UTIs) caused by Escherichia coli represent a significant public health concern due to the high virulence and antimicrobial resistance exhibited by these pathogens. This study aimed to analyze the phylogenetic diversity and antibiotic resistance profiles of Uropathogenic E. coli (UPEC) strains isolated from UTI patients in Algeria, focusing on virulence factors such as extended β-lactamase (ESBL) production, biofilm formation, and hemolytic activity. Phylogenetic grouping of 86 clinical imipenem resistant E. coli isolates showed the prevalence of group B2 (48.9%), followed by groups E (22.1%), unknown (12.8%), A (8.1%), and B1 (4.7%), and Clade I, D, Clade I, or Clade II (1.2%). The highest resistance rates were observed towards amoxicillin (86.04%), ticarcillin (82.55%), piperacillin (73.25%), nitrofurantoin (84.88%), and trimethoprim-sulfamethoxazole (51.16%). Notably, 69.8% of UPEC strains were multidrug-resistant (MDR) and 23.2% were extensively drug-resistant (XDR). Additionally, 48.9%, 42%, and 71% of strains demonstrated ESBL production, hemolytic activity, and weak biofilm production, respectively. Continuous monitoring and characterization of UPEC strains are essential to track the spread of the most resistant and virulent phylogenetic groups over time, facilitating rapid therapeutic decisions to treat infections and prevent the emergence of new resistant organisms, helping choose the most effective antibiotics and reducing treatment failure. [ABSTRACT FROM AUTHOR]

Background: The study aims to investigate the effect of combining silver nanoparticles (AGNPs) with different antibiotics on multi-drug resistant (MDR) and extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa (P. aeruginosa) and to investigate the mechanism of action of AGNPs. Methods: AGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors. Results: TEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5–9, 2–9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors. Conclusion: AGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa. [ABSTRACT FROM AUTHOR]

Carbapenemase-producing Enterobacterales are increasingly being recognized in nosocomial infections. The performance of a flow cytometry-based rapid assay for their detection and differentiation was evaluated. This is a disruptive phenotypic technology, phenotypic and growth-independent, that searches for the lesions produced by drugs acting on cells after a short incubation time. Overall, 180 Gram-negative bacteria were studied, and results were compared with those obtained molecularly by PCR and phenotypically by 'KPC, MBL and OXA-48 Confirm Kit'. This phenotypic method was used as reference for comparison purposes. Susceptibility to carbapenems (imipenem, meropenem, and ertapenem) was determined by standard broth microdilution. Overall, 112 isolates (62.2%) were carbapenemase producers, 41 KPCs, 36 MβLs, and 31 OXA-48, and 4 strains were KPC + MβL co-producers. Sixty-eight isolates were carbapenemase-negative. The percentage of agreement, sensitivity, and specificity were calculated according to ISO 20776-2:2021. The FASTinov assay showed 97.7% agreement with the reference method for carbapenemase detection. Discrepant flow cytometry results were obtained in four isolates compared with both reference and PCR results. The sensitivity and specificity of this new technology were 95.3% and 98.5%, respectively, for KPCs, 97.6% and 99.3% for MβLs, and 96.9% and 98% for OXA-48 detection. In conclusion, we describe a rapid flow cytometry assay with high accuracy for carbapenemase detection and the differentiation of various carbapenemases, which should impact clinical microbiology laboratories and patient management. [ABSTRACT FROM AUTHOR]

Gram-negative antibiotic resistance continues to grow as a global problem due to the evolution and spread of β-lactamases. The early β-lactamase inhibitors (BLIs) are characterized by spectra limited to class A β-lactamases and ineffective against carbapenemases and most extended spectrum β-lactamases. In order to address this therapeutic need, newer BLIs were developed with the goal of treating carbapenemase producing, carbapenem resistant organisms (CRO), specifically targeting the Klebsiella pneumoniae carbapenemase (KPC). These BL/BLI combination drugs, avibactam/avibactam, meropenem/vaborbactam, and imipenem/relebactam, have proven to be indispensable tools in this effort. However, non-KPC mechanisms of resistance are rising in prevalence and increasingly challenging to treat. It is critical for clinicians to understand the unique spectra of these BL/BLIs with respect to non-KPC CRO. In Part 1of this 2-part series, we describe the non-KPC attributes of the newer BL/BLIs with a focus on utility against Enterobacterales and Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

The phenomenon of bacterial resistance to antibiotics, the emission and spread of these bacteria, and the genes that determine antibiotic resistance in the environment are now a major health security concern. This is especially important for anthropopressed surface waters used for recreational purposes. A particular threat is the occurrence of bacteria resistant to frequently applied pharmaceuticals, especially those used to treat persistent and complicated bacterial infections. Hence, a preliminary study of the occurrence of bacteria and genes determining resistance to selected antibiotics, ciprofloxacin and imipenem, was conducted in the bathing waters of the Great Rudnickie Lake. The research showed that the resistance to ciprofloxacin was exhibited by 28% of the total mesophilic bacteria present in water, while the resistance to imipenem was detected in 3.6% of them. It was found that 17–40% of ciprofloxacin-resistant isolates contained the fluoroquinolone-resistance gene qnrS, while the β-lactam-resistance gene blaTEM was found in all the imipenem-resistant strains. The increase in the number of bacteria resistant to the tested antibiotics in the waters of the river outflowing from the lake was observed compared to the inflowing waters, suggesting the potential of the water reservoir as a site for the spreading of drug resistance against tested antibiotics. [ABSTRACT FROM AUTHOR]

Background and Aim: Recently, the rise in various carbapenemases in Enterobacteriaceae poses a significant challenge to the healthcare systems and limits the treatment options. This study aimed to evaluate different assays such as disc diffusion, VITEK, and Rapidec® Carba NP test for the carbapenemase detection, and investigate the synergistic effects of ceftazidimeavibactam (CAZ/AVI) and aztreonam (AZM) combination therapy using the E-strip method. Materials and Methods: This prospective study was conducted on the samples collected from January 2023 to February 2024 at the Department of Microbiology, Central Laboratory Sree Balaji, Medical College and Hospital Chennai, India. The isolates were cultured and identified using the standard biochemical methods followed by the antibiotic susceptibility testing (AST) both by Kirby Bauer disc diffusion (DD) and the VITEK®2 system. The Rapidec® Carba NP test was performed in detecting carbapenemase. The efficacy and potential synergistic effects of the combination treatment comprising CAZ/AVI and AZM were performed using the E-strip gradient stacking method. Results and Conclusion: According on the AST, the highest resistance rates were detected for ampicillin (78%), then, followed by amoxicillin/clavulanic acid (52%), meropenem (56%), imipenem (56%), cefazolin (56%), and ciprofloxacin (53%). The lowest resistance rates were found for gentamicin (23%), cotrimoxazole (27%), piperacillin/tazobactam (27%), and tobramycin (33%). Rapidec® Carba NP test detected 65 bacterial isolates stored in the laboratory, resulting in a sensitivity of 97% for carbapenemase detection. For carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates, synergy was observed between CAZ/AVI E-strip and AZM E-strip in 66 out of 67 isolates (98.75%). The Rapidec® Carba NP test remains a valuable tool for the initial screening, providing timely information for the clinicians. The high rate of synergy observed in our study suggests that CAZ/AVI and AZM will provide a promising treatment option for the CRKP infections, particularly in the settings with limited therapeutic alternatives. [ABSTRACT FROM AUTHOR]

Purpose: The current study evaluated the in vitro activities of ceftolozane/tazobactam (C/T), imipenem/relebactam (IMI/REL), and comparators against recent (2017–2021) clinical isolates of gram-negative bacilli from two countries in southern Europe. Methods: Nine clinical laboratories (two in Greece; seven in Italy) each collected up to 250 consecutive gram-negative isolates per year from lower respiratory tract, intraabdominal, urinary tract, and bloodstream infection samples. MICs were determined by the CLSI broth microdilution method and interpreted using 2022 EUCAST breakpoints. β-lactamase genes were identified in select β-lactam-nonsusceptible isolate subsets. Results: C/T inhibited the growth of 85–87% of Enterobacterales and 94–96% of ESBL-positive non-CRE NME (non-Morganellaceae Enterobacterales) isolates from both countries. IMI/REL inhibited 95–98% of NME, 100% of ESBL-positive non-CRE NME, and 98–99% of KPC-positive NME isolates from both countries. Country-specific differences in percent susceptible values for C/T, IMI/REL, meropenem, piperacillin/tazobactam, levofloxacin, and amikacin were more pronounced for Pseudomonas aeruginosa than Enterobacterales. C/T and IMI/REL both inhibited 84% of P. aeruginosa isolates from Greece and 91–92% of isolates from Italy. MBL rates were estimated as 4% of Enterobacterales and 10% of P. aeruginosa isolates from Greece compared to 1% of Enterobacterales and 3% of P. aeruginosa isolates from Italy. KPC rates among Enterobacterales isolates were similar in both countries (7–8%). OXA-48-like enzymes were only identified in Enterobacterales isolates from Italy (1%) while GES carbapenemase genes were only identified in P. aeruginosa isolates from Italy (2%). Conclusion: We conclude that C/T and IMI/REL may provide viable treatment options for many patients from Greece and Italy. [ABSTRACT FROM AUTHOR]

Introduction: Since its discovery in 1961, methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a significant healthcare-associated pathogen (HA-MRSA) and a notorious 'superbug'. Typing is crucial for surveillance, epidemiology analysis, infection control of MRSA and sequencing of the spa gene is one of the most common methods used for determining the origin of this bacterium in humans and animals. This research aimed to determine the antibiotic resistance and spa type of S. aureus strains collected from outpatients in two hospitals in the Wasit province of Iraq. Material & Methods: The study analyzed 200 outpatient MRSA isolates by collecting nasal and sputum samples from patients. Standard biochemical and molecular methods based on the nuc gene were used to identify S. aureus bacteria and amplify the mecA and spa genes. The Kirby-Bauer disc diffusion method was employed to determine the antibiotic sensitivity of the isolates using penicillin, cefoxitin, vancomycin, gentamicin, erythromycin, tetracycline, imipenem, clindamycin, chloramphenicol and rifampicin. Results: Methods. The prevalence of MRSA was more common in women than in men. Antibiogram results showed that most of the isolates were resistant to penicillin (94.2%) and sensitive to imipenem (100%), clindamycin (100%), and chloramphenicol (100%). Of these 35 isolates, 30 (87.5%) and 26 strains (74.3%) were positive for the mecA and spa genes. Typing based on spa gene sequencing revealed four different patterns: t386, t3579, U0002 and U0234. Conclusion: Variations in the spa gene among different S. aureus isolates may he of clinical importance when treating staphylococcal infections. In this study, spa typing revealed four different patterns in Iraq, representing diagnostic and therapeutic implications. [ABSTRACT FROM AUTHOR]

This study assessed wastewater treatment by visible-light/Peroxymonosulfate process using its linking with TiO2@Fe3O4 nanoparticles coated on chitosan. Meropenem and Imipenem photodegradation was evaluated as a model-resistant contaminant by TiO2@Fe2O3/chitosan nanocomposite. The synthesised TiO2@Fe2O3/chitosan was characterised using various techniques. Fe2O3 and TiO2 nanoparticles on the chitosan surface were affirmed via XRD, EDX, and FTIR findings. The FESEM and TEM results verified the deposition of TiO2@Fe2O3 on the chitosan surface. Under optimum circumstances (pH = 4, catalyst dosage = 0.5 g/L, antibiotics concentration = 25 mg/L reaction time = 30 min, and PMS = 2 mM), maximum degradation efficiency was obtained at about 95.64 and 93.9% for Meropenem and Imipenem, respectively. Also, the experiments demonstrated that TiO2@Fe2O3/chitosan had a better performance than photolysis and adsorption by catalyst without visible light irradiation in degrading antibiotics. The scavenger tests confirmed that ${\rm O}_2^{\cdot -}$ O 2 ⋅ − , ${\rm SO}_4^{\cdot -}$ SO 4 ⋅ − , ${\rm HO}\cdot$ HO ⋅ , and h+ are present simultaneously during the pollutant photodegradation process. After five recovery cycles, the system eliminated over 80 percent of antibiotics. It suggested that the catalyst's capacity to be reused may be cost-effective. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to evaluate the predictors associated with target concentration (non-)attainment of imipenem in critically ill patients. The secondary objective was to explore the correlation between achieving imipenem target concentrations and clinical outcomes of therapy. A retrospective cohort study was conducted in critically ill patients treated with imipenem. Clinical data were extracted from the patients' electronic medical records. The pharmacokinetic/pharmacodynamic target was defined as free imipenem concentrations above the minimum inhibitory concentration (MIC) of the pathogen at 100% (100%fT>MIC) of the dosing interval. Factors associated with the non-attainment of target concentrations were evaluated using binomial logistic regression. Kaplan-Meier analysis was used to investigate the correlation between (non-)attainment targets and 30-day mortality. A total of 406 patients were included, and 55.4% achieved the target of 100%fT>MIC. Regression analysis identified an initial daily dose of imipenem ≤ 2 g/day, augmented renal clearance, age ≤ 60 years, recent surgery, and absence of positive microbiology culture as risk factors for target non-attainment. Achieving the 100%fT>MIC target was significantly associated with clinical efficacy but not with 30-day mortality. Selective application of therapeutic drug monitoring in the early stages of imipenem treatment for critically ill patients can improve clinical outcomes. Further research should explore the potential benefits of TDM-guided dosing strategies for imipenem in critical care settings. [ABSTRACT FROM AUTHOR]

OXA-244, an R214G variant of OXA-48, is silently spreading worldwide likely because of difficulties in detection using classical screening media. Here, we characterized two clinical isolates of Escherichia coli and Citrobacter youngae that displayed reduced susceptibility to carbapenems but were lacking significant carbapenemase activity as revealed by negative Carba NP test results. However, positive test results were seen for OXA-48-like enzymes by lateral flow immunoassays. WGS revealed the presence of a blaOXA-181-like gene that codes for OXA-484, an R214G variant of OXA-181. BlaOXA-484 gene was located on a 58.4-kb IncP1-like plasmid (pN-OXA-484), that upon transfer into E. coli HB4 with impaired permeability, conferred carbapenem and temocillin resistance (MICs > 32 mg/L). E. coli TOP10 (pTOPO-OXA-484) revealed reduced MICs in most substrates as compared to E. coli TOP10 (pTOPO-OXA-181), especially for imipenem (0.25 mg/L versus 0.75 mg/L) and temocillin (16 mg/L versus 1028 mg/L). Catalytic efficiencies of OXA-484 were reduced as compared to OXA-181 for most ß-lactams including imipenem and temocillin with 27.5- and 21.7-fold reduction, respectively. Molecular modeling confirmed that the salt bridges between R214, D159, and the R1 substituent's carboxylate group of temocillin were not possible with G214 in OXA-484, explaining the reduced affinity for temocillin. In addition, changes in active site's water network may explain the decrease in hydrolysis rate of carbapenems. OXA-484 has weak imipenem and temocillin hydrolytic activities, which may lead to silent spread due to underdetection using selective screening media or biochemical imipenem hydrolysis confirmatory tests. [ABSTRACT FROM AUTHOR]

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Introduction: Urinary tract infection (UTI) is the most common infection of the pediatric age group. Several factors linked to higher prevalence include poor personal hygiene, improper sanitation, lower socioeconomic status, and malnourishment. In addition to having a worse quality of life, the 1.8 million children who live in Karachi's Korangi district are routinely exposed to such factors. Objectives: The study aims to evaluate the frequency of UTI and distribution of uropathogens along with their antimicrobial susceptibility pattern in patients presenting to a pediatric tertiary care center in the Korangi district of Karachi, Pakistan. Design: The study employed an observational cross-sectional design. Methods: The study was conducted at the Microbiology laboratory of Sindh Institute of Child Health and Neonatology, Karachi, Pakistan from 1st January to 15th August 2023. Urine samples of patients 1 to 16 years of age were collected via midstream clean catch method and of patients from birth up to 1 year were collected in urine collection bags. The samples were cultured on Cystine Lactose Electrolyte Deficient (CLED) agar and antibiotic susceptibility testing was performed using the Kirby-Bauer Disc Diffusion method. Results: A total of 457 urine samples were collected, of which 90 (19.7%) were positive for significant uropathogens. With a mean age of 4.6 years, majority of the culture-positive patients were female (n = 72; 80%). Enterobacterales were the most frequently isolated (n = 88; 95.6%), of which Escherichia coli was the most common (73.9%; n = 68). Citrobacter (n = 7; 7.6%), Klebsiella (n = 6; 6.5%), Serratia (n = 4; 4.3%), Proteus (n = 2; 2.2%), Salmonella (n = 2; 2.2%), and Enterobacter (n = 1; 1.1%) were among the other Enterobacterales isolated. Meropenem and imipenem were the most effective in isolates from Enterobacterales (n = 88) followed by amikacin (n = 84), ciprofloxacin (n = 75), and piperacillin-tazobactam (n = 70). Ceftriaxone and cefixime exhibited moderate susceptibility (n = 69 and 52) whereas, amoxicillin-clavulanate was the least susceptible (n = 3). Conclusion: We report high frequency of UTI in our pediatric population with uropathogens and associated antimicrobial susceptibility pattern confirming to the existing trends of pediatric UTIs in Pakistan. In addition to valuable insights for treating patients under similar conditions, our study serves as a catalyst for further multi-center research in this area. [ABSTRACT FROM AUTHOR]