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Introduction: Osteomyelitis can occur at various osseous locations and commonly presents in the emergency department (ED). The incidence of osteomyelitis is 21.8 cases per 100,000 persons annually.1 Hematogenous osteomyelitis typically occurs in the vertebrae; however, it may seldomly occur in the manubrium. Hematogenous osteomyelitis can be seen in patients with complicated thoracic surgery, radiation, fracture, diabetes, immunosuppression, steroid therapy, and malnutrition.2 Because signs and symptoms of osteomyelitis may be nonspecific, clinicians must have high suspicion based on history and physical. Workup should include identifying the source, imaging, and surgical cultures.Case Report: A 60-year-old male with hypertension and diabetes presented with atraumatic right shoulder and chest pain. The patient presented twice to the ED for clavicle pain five days prior. Computed tomography (CT) of the chest detected osseous infection of the manubrium and upper sternum, right clavicle, and mediastinal phlegmon. A CT of the abdomen and pelvis revealed osteomyelitis and discitis of the 12th thoracic and first lumbar vertebral body with gas at the psoas muscle, as well as sigmoid diverticulitis with colovesicular fistula. The patient was started on broad spectrum antibiotics and 1,500 milliliters of lactated Ringer’s in the ED. After evaluation by cardiothoracic surgery, the patient was taken to the operating room for neck exploration, incision/drainage, manubriectomy, and right sternoclavicular joint resection. Surgical, blood, urine, and respiratory cultures grew Klebsiella pneumoniae. After a 34-day hospital course, the patient was discharged on two weeks of oral levofloxacin and follow-up appointments with cardiothoracic surgery and infectious disease. The patient had good prognosis and recovery.Conclusion: Hematogenous osteomyelitis to the manubrium is rare and may present with only chest pain. It is important to consider other sources that seed in the manubrium and imaging to evaluate multisite infection. Treatment should include intravenous antibiotics and/or surgical intervention for debridement with washout or manubriectomy.

Introduction Bloodstream infections are a significant threat to soldiers wounded in combat and contribute to preventable deaths. Novel and combination therapies that can be delivered on the battlefield or in lower roles of care are urgently needed to address the threat of bloodstream infection among military personnel. In this manuscript, we tested the antibacterial capability of silver ions (Ag+), with long-appreciated antibacterial properties, against ESKAPEE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species, and Escherichia coli) pathogens. Materials and Methods We used the GENESYS (RAIN LLC) device to deliver Ag+ to Gram-positive and Gram-negative ESKAPEE organisms grown in broth, human blood, and serum. Following the Ag+ treatment, we quantified the antibacterial effects by quantifying colony-forming units. Results We found that Ag+ was bactericidal against 5 Gram-negative organisms, K pneumoniae, A baumannii, P aeruginosa , E cloacae , and E coli , and bacteriostatic against 2 Gram-positive organisms, E faecium and S aureus. The whole blood and serum inhibited the bactericidal activity of Ag+ against a common agent of bloodstream infection, P aeruginosa. Finally, when Ag+ was added in conjunction with antibiotic in the presence of whole blood, there was no significant effect of Ag+ over antibiotic alone. Conclusions Our results confirmed that Ag+ has broad-spectrum antibacterial properties. However, the therapeutic value of Ag+ may not extend to the treatment of bloodstream infections because of the inhibition of Ag+ activity in blood and serum. [ABSTRACT FROM AUTHOR]

Medicinal plants provide a significant supply of natural compounds that can be used to develop new therapeutic medicines for treating severe illnesses including microbial infections. The genus Bambusa, which belongs to the Poaceae family, encompasses a vast and widely distributed collection of plants that possess a wide range of traditional uses in the treatment of various diseases. This study examined the ethanolic extracts of Bambusa tulda, along with its fractions such as ethyl acetate, petroleum ether, n-butanol, and water, to investigate their qualitative and quantitative phytochemical, antioxidant, and antibacterial properties. FTIR analysis of ethanolic powdered shoot extracts shows, presence of different functional groups including C-H, C-O, O-H and aromatic groups by showing stretching’s in different wavelengths. The extracts underwent testing to evaluate their antimicrobial activity against various strains of bacteria by using agar disc diffusion method and micro-dilution techniques to determine the minimum inhibitory and bactericidal concentrations. Additionally, the antioxidant activity of the extracts was assessed using the scavenging activity of DPPH radical methods. The extracts exhibited a robust positive connection between their antioxidant activity and the combined amounts of phenolics and flavonoids. The IC50 values of n-butanol, ethanol, water, petroleum ether, and ethyl acetate fraction show in ascending order 10.77+0.24 μg/ml, 11.35+0.13 μg/ml, 13.36+0.11 μg/ml,13.93+0.71 μg/ml and14.25+ 0.27 μg/ml respectively. The extracts have been shown effective efficacy against Escherichia coli and Staphylococcus aureus bacteria. However, it did not show any responses against Klebsiella pneumoniae and Pseudomonas aeruginosa. Escherichia coli exhibited greater susceptibility to the extracts compared to S. aureus, with the n-butanol fraction being the most potent extract. [ABSTRACT FROM AUTHOR]

Purpose: Liver abscesses concomitant with acute prostatitis are rare and potentially fatal. We analyzed the occurrence of this condition and clinical characteristics of the affected patients. Materials and Methods: The medical records of 474 patients diagnosed with acute prostatitis between June 2006 and July 2022 were retrospectively reviewed. Patients in whom pathogens were not detected in serum or urine cultures were excluded. A total of 271 patients were included in the analysis. Patient characteristics and laboratory test results were compared between patients with acute prostatitis with and without liver abscesses. Results: Fifteen patients (5.5%) were identified with simultaneous liver abscesses and acute prostatitis. The liver abscess group was younger than the non-liver abscess group in terms of mean age. In the univariate analysis, a high proportion of patients had diabetes mellitus, whereas a low proportion had hypertension. None of the underlying diseases, including benign prostatic hyperplasia, malignancy, or alcoholism, demonstrated a significant association with liver abscess in multivariate analysis; however, an association was observed in liver function test results. All patients with liver abscesses tested positive for Klebsiella pneumoniae. Conclusions: When K. pneumoniae is identified in patients with acute prostatitis and abnormal liver function tests, considering the possibility of metastatic infection in other organs, including the liver, and performing an active evaluation is essential. [ABSTRACT FROM AUTHOR]

Background: Infections caused by Klebsiella pneumoniae are common and result in high mortality rates. In vitro studies demonstrated the potency of cefoperazone/sulbactam (CPZ/SUL) against Klebsiella pneumoniae. However, the clinical efficacy of CPZ/SUL for the treatment of K. pneumoniae bacteremia has not been studied. Objectives: This study aimed to associate the clinical outcomes of patients with bacteremia with the minimal inhibitory concentrations (MICs) of CPZ/SUL against the causative K. pneumoniae isolates. Methods: This multicenter, retrospective study was conducted in Taiwan between July 2017 and April 2021. Patients with K. pneumoniae bacteremia treated with CPZ/SUL were enrolled in this study. CPZ/SUL MICs were determined using the agar dilution method. Data on the patients' clinical outcomes and characteristics were collected and analyzed. Results: In total, 201 patients were enrolled. Among the causative K. pneumoniae isolates, 180 (89.5%) were susceptible to CPZ/SUL. Most patients (n = 156, 77.6%) had favorable outcomes. The 30-day mortality rate was 11.9% (n = 24). Multivariate risk analyses showed that higher APACHE II score (Odds Ratio [OR], 1.14; Confidence Interval [CI], 1.07–1.21; p < 0.001), metastatic tumors (OR, 5.76; CI, 2.31–14.40; p < 0.001), and causative K. pneumoniae CPZ/SUL MICs > 16 µg/ml (OR, 4.30; CI, 1.50–12.27; p = 0.006) were independently associated with unfavorable outcomes. Conclusion: Patients with K. pneumoniae bacteremia treated with CPZ/SUL at a ratio 1:1 had favorable outcomes when the CPZ/SUL MICs were ≤ 16 µg/ml. Patients with higher APACHE II scores and metastatic tumors had unfavorable outcomes. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae , a highly prevalent Gram-negative bacterium, is widely known for causing nosocomial infections, leading to various diseases including systemic infections and fever. In traditional medicine, Launaea nudicaulis (L.) Hook. f. (Asteraceae), is often used to alleviate fever caused by bacterial infections. This study aimed to assess the antibacterial efficacy of the key phytochemicals present in the extract of L. nudicaulis against a panel of K. pneumoniae isolates. Three main constituents were isolated from this plant: cichorin (1), methyl-3,5-di- O -caffeoylquinate (syn. macranthoin G) (2), and cynaroside (3). Among these compounds, macranthoin G demonstrated notable antibacterial activity, with minimum inhibitory concentrations ranging from 64 to 256 µg/mL. It was found to inhibit the growth of the tested isolates and significantly affect the integrity of their cell membranes in 65.2 % of cases. Moreover, it increased the permeability of both the inner and outer membranes in 60.87 % and 52.17 % of K. pneumoniae isolates, respectively. Docking studies revealed that it exhibited strong binding scores to LpxC and FabI enzymes, with significant interactions occurring with key amino acids in their active sites. Based on these findings, macranthoin G shows promise as a potential antimicrobial drug, warranting further research to validate its antimicrobial and pharmacokinetic properties. [Display omitted] • Three main components were isolated from Launaea naudicaulis. • The isolated compounds are cichorin, macranthoin G, and cynaroside. • Macranthoin G exhibited notable antibacterial action. • It impaired the inner and outer membrane integrity of Klebsiella pneumoniae. • It showed significant docking scores and interactions with LpxC and FabI enzymes. [ABSTRACT FROM AUTHOR]

Bacteriocins are antimicrobial peptides produced by bacteria to prevent the growth of pathogens. Combining bacteriocins with metal nanoparticles, like silver nanoparticles (AgNPs), has developed into a viable strategy to get over bacteriocin limitations. In this study, bacteriocin BacZY05 was extracted from Bacillus subtilis ZY05 and purified using various techniques. The resulting purified bacteriocin was then combined with silver nanoparticles to form bacteriocin silver nanoconjugates (BacZY05-AgNPs). The physicochemical properties of the BacZY05-AgNPs were characterized using various analytical techniques. The mean diameter of the synthesized AgNPs was approximately 20–60 nm with an oval or spherical shape. The antimicrobial activity of the BacZY05-AgNPs was evaluated against several indicator strains by their zone of inhibition (ZOI), using the agar well diffusion method. Compared to bacteriocin (ZOI- 13 to 20 mm) and AgNPs (ZOI- 10–22 mm) alone, the antibacterial activity data demonstrated a 1.3-1.5-fold increase in the activity of bacteriocin-nanoconjugates (ZOI- 22 to 26 mm). For Staphylococcus aureus MTCC3103 and Klebsiella pneumoniae MTCC109, BacZY05-capped AgNPs exhibited the lowest minimum inhibitory concentration (MIC), measuring 10.93 µg/mL. For Salmonella typhi NCIM2501, the MIC was 28.75 µg/mL. The highest MIC value was 57.5 µg/mL for Escherichia coli DH5α and Vibrio cholerae MTCC3909. With BacZY05-capped AgNPs, the lowest minimum bactericidal concentration (MBC) of 28.75 µg/mL was observed for Staphylococcus aureus MTCC31003. In the cases of Salmonella typhi NCIM2501 and Klebsiella pneumoniae MTCC109 concentration was 57.5 µg/mL. Vibrio cholerae MTCC3909 and Escherichia coli DH5α had the highest MBC values at 115 µg/mL. [ABSTRACT FROM AUTHOR]

Background: Klebsiella pneumoniae species complex (KpSC) is an important disseminator of carbapenemase‐encoding genes, mainly blaKPC‐2 and blaNDM‐1, from hospitals to the environment. Consequently, carbapenem‐resistant strains can be spread through the agrifood system, raising concerns about food safety. This study therefore aimed to isolate carbapenem‐resistant KpSC strains from the agricultural and environmental sectors and characterize them using phenotypic, molecular, and genomic analyses. Results: Klebsiella pneumoniae and Klebsiella quasipneumoniae strains isolated from soils used for lemon, guava, and fig cultivation, and from surface waters, displayed an extensive drug‐resistance profile and carried blaKPC‐2, blaNDM‐1, or both. In addition to carbapenemase‐encoding genes, KpSC strains harbor a broad resistome (antimicrobial resistance and metal tolerance) and present putative hypervirulence. Soil‐derived K. pneumoniae strains were assigned as high‐risk clones (ST11 and ST307) and harbored the blaKPC‐2 gene associated with Tn4401b and Tn3‐like elements on IncN‐pST15 and IncX5 plasmids. In surface waters, the coexistence of blaKPC‐2 and blaNDM‐1 genes was identified in K. pneumoniae ST6326, a new carbapenem‐resistant regional Brazilian clone. In this case, blaKPC‐2 with Tn4401a isoform and blaNDM‐1 associated with a Tn125‐like transposon were located on different plasmids. Klebsiella quasipneumoniae ST526 also presented the blaNDM‐1 gene associated with a Tn3000 transposon on an IncX3 plasmid. Conclusion: These findings provide a warning regarding the transmission of carbapenemase‐positive KpSC across the agricultural and environmental sectors, raising critical food safety and environmental issues. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A total of sixty-two isolates were tested to assess the presence of the irp2 gene in different isolates of Klebsiella pneumoniae. The isolates discussed in this study were obtained from patients who had acquired illnesses either within the hospital premises or in the surrounding vicinity. These isolates were sourced from three hospitals located in Baghdad, namely Al-Imam Ali, Al-Zaafaranya, and Ibin-Albady hospitals. One interesting thing about Klebsiella pneumoniae is that it makes siderophores, especially yersiniabactin. This is because of a gene that controls this trait. The application of DNA sequencing methodologies has facilitated the identification of the irp2 gene in 44% of Klebsiella pneumoniae. According to amino acid sequences and differentiation of nucleotide, the current work reports findings on the identification of the K. pneumoniae irp2 gene isolates collected from patients in Iraq. This event represents the initial recorded occurrence of such detection. The presence of this gene is considered an unconventional human pathogen. The aim is to explore the correlation between genetic analysis and the diagnosis of genetic variation by examining isolates documented in the global GenBank database (LC791754.1, LC791755.1, LC791756.1, LC791757.1, LC791758.1, LC791759.1, LC791760.1). Additionally, it seeks to provide insights into the magnitude of genetic variation observed within these isolates. [ABSTRACT FROM AUTHOR]

Phosphorus in wastewater influents is a global issue. Controlling eutrophic water is crucial. Biological phosphorus removal is an economically and environmentally sustainable method for removing phosphorus from wastewater. This study aims to isolate and improve the capacity of aerobic phosphorus-removing bacteria to reduce excessive phosphate concentrations in the environment. Only three out of fourteen bacterial isolates demonstrated the highest phosphate removal efficiency using Toluidine blue-O. Klebsiella pneumoniae 6A, Klebsiella quasipneumoniae 6R, and Enterobacter mori 8R were isolated from activated sludge and identified by 16srRNA. In a single-factor experiment, the effect of incubation periods, phosphate concentrations, carbon sources, sodium acetate concentrations, temperature, pH, and irradiation dosages were studied. Seventy-two hours of incubation, 55 mg/L PO4, sodium acetate as the carbon source, 30°C and pH 7 resulted in maximum phosphorus removal. After optimising the parameters, the removal efficiency of Klebsiella pneumoniae 6A, Klebsiella quasipneumoniae 6R, and Enterobacter mori 8R increased from 73.5% to 85.1%, 79.1% to 98.1%, and 80.6% to 91.9%, respectively. Gamma irradiation showed significant results only in Klebsiella pneumoniae 6A where 100 Gy increased the phosphorous removal efficiency from 85.1% to 100%. Immobilised mixed culture of the three strains adapted better to 100 mg/L Phosphorus than pure cells. Therefore, this technique holds great new promise for phosphorus-contaminated sites bioremediation. [ABSTRACT FROM AUTHOR]

Background: Carbapenem resistance in Pseudomonas aeruginosa is a serious global health problem. We investigated the clonal distribution and its association with the carbapenem resistance mechanisms of carbapenem-non-susceptible P. aeruginosa isolates from three Korean hospitals. Methods: A total of 155 carbapenem-non-susceptible P. aeruginosa isolates collected between 2011 and 2019 were analyzed for sequence types (STs), antimicrobial susceptibility, and carbapenem resistance mechanisms, including carbapenemase production, the presence of resistance genes, OprD mutations, and the hyperproduction of AmpC ß-lactamase. Results: Sixty STs were identified in carbapenem-non-susceptible P. aeruginosa isolates. Two high-risk clones, ST235 (N=41) and ST111 (N=20), were predominant; however, sporadic STs were more prevalent than high-risk clones. The resistance rate to amikacin was the lowest (49.7%), whereas that to piperacillin was the highest (92.3%). Of the 155 carbapenem-non-susceptible isolates, 43 (27.7%) produced carbapenemases. Three metallo-β-lactamase (MBL) genes, blaIMP-6 (N=38), blaVIM-2(N=3), and blaNDM-1(N=2), were detected. blaIMP-6 was detected in clonal complex 235 isolates. Two ST773 isolates carried blaNDM-1 and rmtB. Frameshift mutations in oprD were identified in all isolates tested, regardless of the presence of MBL genes. Hyperproduction of AmpC was detected in MBL gene-negative isolates. Conclusions: Frameshift mutations in oprD combined with MBL production or hyperproduction of AmpC are responsible for carbapenem resistance in P. aeruginosa. Further attention is required to curb the emergence and spread of new carbapenem-resistant P. aeruginosa clones. [ABSTRACT FROM AUTHOR]

Introduction: The emergence of disinfectant resistance has become a severe threat due to reduced effectiveness. This study was undertaken to determine how bacteria adapt to survive exposure to disinfectants in the busiest section of a tertiary care hospital in Varanasi, India. Methods: Four isolates (two Klebsiella pneumoniae, Kp1 and Kp2; two Pseudomonas aeruginosa, Pa1 and Pa2) were obtained from chlorhexidine (CHX)-based handwash during microbiological surveillance of "in-use disinfectants" in hospital. Six disinfectants [4% CHX, 2% glutaraldehyde, 7.5% hydrogen peroxide, 1% sodium hypochlorite and 0.1% benzalkonium chloride (BAC), and 70% ethyl alcohol] were tested against these four isolates to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Antibiotic profile, change in MIC on exposure to disinfectants and biofilm formation in the presence and absence of disinfectants was studied. Whole genome sequencing (WGS) was done to identify the resistance mechanisms. Result: The isolates showed the highest MBC/MIC ratio (4) against glutaraldehyde. Exposure to supra-inhibitory concentration of BAC for 21 days resulted in doubling of MIC/MBC. The majority (75%) of the isolates were multidrug resistant. All the isolates were strong biofilm producers. The reduction rate of biofilm formation decreased with an increase in the concentration of disinfectants (p = 0.05 for BAC). WGS revealed multiple AMR genes including blaDIM-1, disinfectant-resistant gene and efflux pump genes. Conclusion: The study emphasized the various adaptation strategies of these isolates for survival in disinfectant environment, thus posing a huge challenge for their control in the hospital environment. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to comprehensively investigate hypervirulent carbapenem-resistant Klebsiella pneumoniae (CR-hvKP) in the Ningbo region. Importantly, we sought to elucidate its molecular characteristics and pathogenic mechanisms. This information will provide evidence-based insights for preventing and controlling nosocomial infections and facilitate improved clinical diagnosis and treatment in this region. Methods: 96 carbapenem-resistant Klebsiella pneumoniae strains were collected from the Ningbo region between January 2021 and December 2022. Whole genome sequencing and bioinformatic methods were employed to identify and characterize CR-hvKP strains at the molecular level. The minimum inhibitory concentrations (MICs) of common clinical antibiotics were determined using the VITEK-2 Compact automatic microbiological analyzer. Plasmid conjugation experiments evaluated the transferability of resistance plasmids. Finally, mouse virulence assays were conducted to explore the pathogenic mechanisms. Results: Among the 96 strains, a single CR-hvKP strain, designated CR-hvKP57, was identified, with an isolation frequency of 1.04%. Whole-genome sequencing revealed the strain to be ST23 serotype with a K1 capsule. This strain harbored three plasmids. Plasmid 1, a pLVPK-like virulence plasmid, carried multiple virulence genes, including rmpA, rmpA2, iroB, iucA, and terB. Plasmid 2 contained transposable element sequences such as IS15 and IS26. Plasmid 3, classified as a resistance plasmid, harbored the blaKPC-3 carbapenem resistance gene. Mouse virulence assays demonstrated a high mortality rate associated with CR-hvKP57 infection. Additionally, there was a significant increase in IL-1β, IL-6, and TNF-α levels in response to CR-hvKP57 infection, indicating varying degrees of inflammatory response. Western blot experiments further suggested that the pathogenic mechanism involves activation of the NF-ΰB signaling pathway. Conclusion: This study confirms the emergence of hypervirulent CR-hvKP in the Ningbo region, which likely resulted from the acquisition of a pLVPK-like virulence plasmid and a blaKPC-3 resistance plasmid by the ST23-K1 type Klebsiella pneumoniae. Our findings highlight the urgent need for more judicious use of antibiotics to limit the emergence of resistance. Additionally, strengthening infection prevention and control measures is crucial to minimize the spread of virulence and resistance plasmids. [ABSTRACT FROM AUTHOR]

Background: Antibiotic resistance among Gram-negative bacteria in intensive care units (ICUs) is linked with high morbidity and mortality in patients. In this study, we estimated the therapeutic coverage of various antibiotics, focusing on cefiderocol and comparators, administered empirically against an infection of unknown origin in the ICU. Methods: In the ARTEMIS surveillance study, susceptibilities of 624 Italian Gram-negative isolates to amikacin, aztreonam-avibactam, cefiderocol, ceftazidime-avibactam, ceftolozane-tazobactam, colistin, imipenem-relebactam, meropenem, and meropenem-vaborbactam were tested by broth microdilution, and results were interpreted by European Committee on Antimicrobial Susceptibility Testing breakpoints. The susceptibility rates from the ARTEMIS study were extrapolated to Gram-negative isolates obtained from 5,774 patients in Italian ICUs in 2021. The sum of the predicted susceptibilities of individual pathogens represented the overall likelihood of in vitro activity of each antibiotic as early targeted therapy for ICU patients. Results: A total of 624 Italian Gram-negative isolates included 206 Pseudomonas aeruginosa, 138 Acinetobacter baumannii, 187 Klebsiella pneumoniae, and 93 Escherichia coli. Against A. baumannii, K. pneumoniae, P. aeruginosa, and E. coli, the overall susceptibility rates for cefiderocol were 87.7%, 96.8%, 99%, and 100%, respectively; and for comparator agents, 8.7–96.4%, 25.7–100%, 73.3–100%, and 89.2–100%, respectively. Among the subset of meropenem-resistant isolates, susceptibility rates of A. baumannii, K. pneumoniae, and P. aeruginosa to cefiderocol were 86.4%, 96.2% and 100%, respectively. Corresponding susceptibility rates to comparator agents were 0–96.8%, 0–100%, and 6.4–100%, respectively. There were no meropenem-resistant isolates of E. coli. The extrapolation of data to isolates from Italian ICUs showed that the highest likelihood of therapeutic coverage, both overall and among meropenem-resistant isolates, was reported for colistin (96.8% and 72.2%, respectively) and cefiderocol (95.7% and 71.4%, respectively). All other antibiotics were associated with a likelihood below 73% overall and between 0% and 41.4% for meropenem-resistant isolates. Conclusions: Based on confirmed susceptibility rates and reported ICU prevalence of multiple Gram-negative species, cefiderocol showed a higher predicted therapeutic coverage and utility in ICUs compared with comparator beta-lactam–beta-lactamase inhibitor antibiotics. Cefiderocol may be a promising early treatment option for patients at high risk of carbapenem-resistant Gram-negative bacterial infections in the ICU. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this work was to assess dynamic cytokine profiles associated with bloodstream infection (BSI) caused by Klebsiella pneumoniae (Kpn) and investigate the clinical features associated with mortality. Methods: A total of 114 patients with positive BSI-Kpn and 12 sepsis individuals without blood positive bacteria culture were followed up. Cytokine profiles were analyzed by multiplex immunoassay on the first, third, seventh and fourteenth day after diagnosis. The test cytokines included arginase, interferon-gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-12 (p70), and IL-23. The minimum inhibitory concentration (MIC) of 24 antibiotics were tested for BSI-Kpn. Risk factors associated with the 30-day mortality and 120-day mortality were evaluated using logistic analyses and nomogram. Results: There were 55 out of 114 patients with BSI-Kpn were included. All isolates showed high susceptibility rate to novel avibactam combinations. The level of arginase was the highest in carbapenem-resistant Kpn (CRKP) patients. The AUCs of arginase, TNF-α and IL-4 reached 0.726, 0.495, and 0.549, respectively, whereas the AUC for the combination of these three cytokines was 0.805. Notably, 120-day mortality in patients with CRKP was higher than carbapenem-sensitive K. pneumoniae (CSKP). Furthermore, the long-term and high levels of IL-6 and IL-10 were associated with death. Conclusions: High expression of arginase is correlated with CRKP. In addition, BSI-CRKP could result in indolent clinic course but poor long-term prognosis. Continuous increase of IL-6 and IL-10 were associated with mortality. [ABSTRACT FROM AUTHOR]

Clinical metagenomics (CMg) Nanopore sequencing can facilitate infectious disease diagnosis. In China, sub-lineages ST11-KL64 and ST11-KL47 Carbapenem-resistant Klebsiella pneumoniae (CRKP) are widely prevalent. We propose PathoTracker, a specially compiled database and arranged method for strain feature identification in CMg samples and CRKP traceability. A database targeting high-prevalence horizontal gene transfer in CRKP strains and a ST11-only database for distinguishing two sub-lineages in China were created. To make the database user-friendly, facilitate immediate downstream strain feature identification from raw Nanopore metagenomic data, and avoid the need for phylogenetic analysis from scratch, we developed data analysis methods. The methods included pre-performed phylogenetic analysis, gene-isolate-cluster index and multilevel pan-genome database and reduced storage space by 10-fold and random-access memory by 52-fold compared with normal methods. PathoTracker can provide accurate and fast strain-level analysis for CMg data after 1 h Nanopore sequencing, allowing early warning of outbreaks. A user-friendly page (http://PathoTracker.pku.edu.cn/) was developed to facilitate online analysis, including strain-level feature, species identifications and phylogenetic analyses. PathoTracker proposed in this study will aid in the downstream analysis of CMg. This study constructed a database and platform for the characterization of Klebsiellapneumoniae in clinical metagenomic Nanopore sequencing and developed a website for online analysis. [ABSTRACT FROM AUTHOR]

Background: Klebsiella pneumoniae (KP) is the second most prevalent Gram-negative bacterium causing bloodstream infections (BSIs). In recent years, the management of BSIs caused by KP has become increasingly complex due to the emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP). Although numerous studies have explored the risk factors for the development of CRKP-BSIs, the mortality of patients with KP-BSIs, and the molecular epidemiological characteristics of CRKP, the variability in data across different populations, countries, and hospitals has led to inconsistent conclusions. In this single-center retrospective observational study, we utilized logistic regression analyses to identify independent risk factors for CRKP-BSIs and factors associated with mortality in KP-BSI patients. Furthermore, a risk factor-based prediction model was developed. CRKP isolates underwent whole-genome sequencing (WGS), followed by an evaluation of microbiological characteristics, including antimicrobial resistance and virulence genes, as well as epidemiological characteristics and phylogenetic analysis. Results: Our study included a total of 134 patients with KP-BSIs, comprising 50 individuals infected with CRKP and 84 with carbapenem-susceptible Klebsiella pneumoniae (CSKP). The independent risk factors for CRKP-BSIs were identified as gastric catheterization (OR = 9.143; CI = 1.357–61.618; P = 0.023), prior ICU hospitalization (OR = 4.642; CI = 1.312–16.422; P = 0.017), and detection of CRKP in non-blood sites (OR = 8.112; CI = 2.130-30.894; P = 0.002). Multivariate analysis revealed that microbiologic eradication after 6 days (OR = 3.569; CI = 1.119–11.387; P = 0.032), high Pitt bacteremia score (OR = 1.609; CI = 1.226–2.111; P = 0.001), and inappropriate empirical treatment after BSIs (OR = 6.756; CI = 1.922–23.753; P = 0.003) were independent risk factors for the 28-day mortality in KP-BSIs. The prediction model confirmed that microbiologic eradication after 6.5 days and a Pitt bacteremia score of 4.5 or higher were significant predictors of the 28-day mortality. Bioinformatics analysis identified ST11 as the predominant CRKP sequence type, with blaKPC−2 as the most prevalent gene variant. CRKP stains carried multiple plasmid-mediated resistance genes along with some virulence genes. Phylogenetic analysis indicated the presence of nosocomial transmission of ST11 CRKP within the ICU. Conclusions: The analysis of risk factors for developing CRKP-BSIs and the association between KP-BSIs and 28-day mortality, along with the development of a risk factor-based prediction model and the characterization of CRKP strains, enhances clinicians' understanding of the pathogens responsible for BSIs. This understanding may help in the timely administration of antibiotic therapy for patients with suspected KP-BSIs, potentially improving outcomes. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a major public health problem, requiring the use of last-resort antibiotics such as colistin. However, there is concern regarding the emergence of isolates resistant to this agent. The report describes two patients with urinary tract infection (UTI) and ventilator-associated pneumonia (VAP) infection caused by CRKP strains. The first case was a 23-year-old male with UTI caused by a strain of ST16 co-harboring blaCTX-M, blaTEM, blaSHV, blaNDM, blaOXA-48-like genes. The second case was a 39-year-old woman with VAP due to hypervirulent ST337-K2 co-harboring blaSHV, blaNDM, blaOXA-48-like,iucA, rmpA2 and rmpA. The patients' general condition improved after combination therapy with colistin (plus meropenem and rifampin, respectively) and both of them recovered and were discharged from the hospital. This study highlights the necessary prevention and control steps to prevent the further spread of CRKP strains should be a priority in our hospital. [ABSTRACT FROM AUTHOR]

One of the most common bacteria that cause nosocomial infections is Klebsiella pneumonia (K. pneumoniae), especially in patients who are very sick and admitted to the intensive care unit (ICU). The frequency of multi-drug-resistant Klebsiella pneumoniae (MDRKP) has dramatically increased worldwide in recent decades, posing an urgent threat to public health. The Western world's bacteriophage (phage) studies have been revitalized due to the increasing reports of antimicrobial resistance and the restricted development and discovery of new antibiotics. These factors have also spurred innovation in other scientific domains. The primary agent in phage treatment is an obligately lytic organism (called bacteriophage) that kills the corresponding bacterial host while sparing human cells and lessening the broader effects of antibiotic usage on commensal bacteria. Phage treatment is developing quickly, leading to many clinical studies and instances of life-saving medicinal use. In addition, phage treatment has a few immunological adverse effects and consequences in addition to its usefulness. Since K. pneumoniae antibiotic resistance has made treating multidrug-resistant (MDR) infections challenging, phage therapy (PT) has emerged as a novel therapeutic strategy. The effectiveness of phages has also been investigated in K. pneumoniae biofilms and animal infection models. Compared with antibiotics, PT exhibits numerous advantages, including a particular lysis spectrum, co-evolution with bacteria to avoid the emergence of phage resistance, and a higher abundance and diversity of phage resources than found in antibiotics. Moreover, phages are eliminated in the absence of a host bacterium, which makes them the only therapeutic agent that self-regulates at the sites of infection. Therefore, it is essential to pay attention to the role of PT in treating these infections. This study summarizes the state of knowledge on Klebsiella spp. phages and provides an outlook on the development of phage-based treatments that target K. pneumoniae in clinical trials. [ABSTRACT FROM AUTHOR]

Introduction: Klebsiella pneumoniae (K. pneumoniae) is the most common pathogen causing hospital respiratory tract infection and epidemic. Gold standard procedures of microscopic examination and biochemical identification are widely used in clinical diagnosis with disadvantages of low sensitivity, time-consuming and sophisticated equipment requiring. An efficient, nucleic acid amplification-based sensitive and specific on-site identification of K. pneumoniae in clinical is necessary to facilitate clinical medication and disease control. Methods: We developed a closed dumbbell mediated isothermal amplification (CDA) assay for the rapid and sensitive detection of conserved rcsA gene in K. pneumoniae by real-time fluorescence monitoring and end-point colorimetric judgement. We designed and selected a pair of inner primers of CDA to detect K. pneumoniae. Then outer and loop primers were designed and verified to accelerate CDA reaction to achieve more efficient detection of K. pneumoniae. Results: The results showed the detection limit of CDA assay was 1.2x10-5 ng/μL (approximately 1 copy of the target gene) within 60 min, which was 100-fold more sensitive than real-time quantitative PCR (qPCR). Several pathogen genomic DNAs (Staphylococcus aureus, Shigella sonnei, Vibrio parahaemolyticus, Escherichia coli, Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida albicans, Streptococcus agalactiae, Rickettsia, Listeria monocytogenes, Pseudomonas aeruginosa, Klebsiella oxytoca, and Klebsiella aerogenes) were used to evaluate the sensitivity and specificity of the established K. pneumoniae CDA assay. Total 224 batches of samples from other strains tested were negative and 296 batches of extracted K. pneumoniae DNA samples were positive by the developed CDA amplification approach, revealing high specificity and specificity of the diagnostic assay. In addition, the results of real-time fluorescence amplification of the K. pneumoniae CDA were in consistent with those of end-point colorimetric results. Discussion: The established real-time fluorescence and visual CDA assays of K. pneumoniae with merits of rapid, sensitive and specificity could be helpful for on-site diagnosis and clinical screening in rural areas. [ABSTRACT FROM AUTHOR]

Background: Klebsiella pneumoniae is the most commonly encountered pathogen in clinical practice. Widespread use of broad-spectrum antibiotics has led to the current global dissemination of carbapenem-resistant K. pneumoniae, which poses a significant threat to antibacterial treatment efficacy and public health. Outer membrane vesicles (OMVs) have been identified as carriers capable of facilitating the transfer of virulence and resistance genes. However, the role of OMVs in carbapenem-resistant K. pneumoniae under external pressures such as antibiotic and phage treatments remains unclear. Methods: To isolate and purify OMVs under the pressure of phages and tigecycline, we subjected K. pneumoniae 0692 harboring plasmid-mediated blaNDM-1 and blaKPC-2 genes to density gradient separation. The double-layer plate method was used to isolate MJ1, which efficiently lysed K. pneumoniae 0692 cells. Transmission electron microscopy (TEM) was used to characterize the isolated phages and extract OMV groups for relevant morphological identification. Determination of protein content of each OMV group was conducted through bicinchoninic acid assay (BCA) and proteomic analysis. Results: K. pneumoniae 0692 released OMVs in response to different environmental stimuli, which were characterized through TEM as having the typical structure and particle size of OMVs. Phage or tigecycline treatment alone resulted in a slight increase in the mean protein concentration of OMVs secreted by K. pneumoniae 0692 compared to that in the untreated group. However, when phage treatment was combined with tigecycline, there was a significant reduction in the average protein concentration of OMVs compared to tigecycline treatment alone. Proteomics showed that OMVs encapsulated numerous functional proteins and that under different external stresses of phages and tigecycline, the proteins carried by K. pneumoniae 0692-derived OMVs were significantly upregulated or downregulated compared with those in the untreated group. Conclusions: This study confirmed the ability of OMVs to carry abundant proteins and highlighted the important role of OMV-associated proteins in bacterial responses to phages and tigecycline, representing an important advancement in microbial resistance research. [ABSTRACT FROM AUTHOR]

Objective: This study used whole-genome sequencing (WGS) to explore the genetic diversity, virulence factors, and antimicrobial resistance determinants of string test-positive Klebsiella pneumoniae (KP) over a 4-year surveillance period in Huzhou, China. Methods: In total, 632 clinical isolates were collected via hospital surveillance from 2020 to 2023; 100 were positive in the string test and these 100 strains were subjected to antimicrobial susceptibility testing using an agar dilution method followed by WGS. Results: The resistance rates to cefotaxime (77.0%), trimethoprimsulfamethoxazole (67.0%), and nalidixic acid (64.0%) were high. Multilocus sequence typing revealed high genetic diversity; there were 33 sequence types (STs) and 15 capsular serotypes. The most common ST was ST23 (16.0%) and the most common capsular serotype was K1 (22.5%). Virulome analysis revealed among-strain differences in virulence factors that affected bacterial adherence, efflux pump action, iron uptake, nutritional factors, metabolic regulation, the secretion system, and toxin production. The Kleborate strain-specific virulence scores of all 100 string test-positive KPs were derived: 28 strains scored 5, 28 scored 4, 21 scored 3, 12 scored 1, and 11 scored 0. All 77 strains with scores of 3 to 5 contained the iucA gene. The phylogeny based on whole-genome single nucleotide polymorphisms (wgSNPs) indicated high clonality; the string testpositive KP strains were grouped into six clades. Closely related isolates in each genetic cluster usually shared STs. Conclusion: The present study highlights the significance of the KP iucA gene in terms of hypervirulence and the diverse genotypes of string test-positive KP strains isolated in Huzhou hospitals. [ABSTRACT FROM AUTHOR]

Background: The emergence and rapid spread of gram-negative bacteria resistant to carbapenems among newborns is concerning on a global scale. Nonetheless, the pooled estimate of gram-negative bacteria resistant to carbapenem that cause neonatal sepsis in developing nations remains unknown. Thus, this study aimed to determine the combined prevalence of gram-negative bacteria resistant to carbapenem in African newborns who were suspected of having sepsis. Methods: All studies published from January 1, 2010, up to December 30, 2023, from PubMed, Science Direct, Scopus electronic databases, and the Google Scholar search engine were researched. Isolates tested for carbapenem from neonates with sepsis, English language papers conducted in Africa, and cross-sectional and cohort studies papers were included. Using PRISMA guidelines, we systematically reviewed and meta-analyzed studies that assessed the prevalence of carbapenem-resistant gram-negative bacteria. The "Joanna Briggs Institute" was used critically to evaluate the quality of the included studies. The data analysis was carried out using STATA™ version 17. Heterogeneity across the studies was evaluated using Q and I 2 tests. The subgroup analysis was done and, funnel plot and Egger's regression test were used to detect publication bias. A sensitivity analysis was conducted. Results: All 36 studies were included in the meta-analysis and systematic review. The pooled prevalence of carbapenem resistance in Africa was 30.34% (95% CI 22.03–38.64%). The pooled estimate of gram-negative bacteria resistant to imipenem, and meropenem was 35.57% (95% CI 0.67–70.54%) and 34.35% (95% CI 20.04% – 48.67%), respectively. A. baumannii and Pseudomonas spp. had pooled prevalence of 45.9% (95% CI 33.1–58.7%) and 43.0% (95% CI 23.0–62.4%), respectively. Similarly, Pseudomonas spp. and A. baumannii also exhibited strong meropenem resistance, with a pooled prevalence of 29.2% (95% CI 4.8–53.5%) and 36.7% (95% CI 20.1–53.3%), respectively. E. coli and K. pneumoniae were the two most common isolates. Conclusion: There should be urgent antimicrobial stewardship practices, strengthened surveillance systems and effective treatment for neonates with sepsis. There was remarkable variation in resistance across the continent. [ABSTRACT FROM AUTHOR]

Background Lysins (cell wall hydrolases) targeting gram-negative organisms require engineering to permeabilize the outer membrane and access subjacent peptidoglycan to facilitate killing. In the current study, the potential clinical utility for the engineered lysin CF-370 was examined in vitro and in vivo against gram-negative pathogens important in human infections. Methods Minimum inhibitory concentration (MICs) and bactericidal activity were determined using standard methods. An in vivo proof-of-concept efficacy study was conducted using a rabbit acute pneumonia model caused by Pseudomonas aeruginosa. Results CF-370 exhibited potent antimicrobial activity, with MIC50/90 values (in µg/mL) for: P aeruginosa , 1/2; Acinetobacter baumannii , 1/1; Escherichia coli , 0.25/1; Klebsiella pneumoniae , 2/4; Enterobacter cloacae 1/4; and Stenotrophomonas maltophilia 2/8. CF-370 furthermore demonstrated bactericidal activity, activity in serum, a low propensity for resistance, anti-biofilm activity, and synergy with antibiotics. In the pneumonia model, CF-370 alone decreased bacterial densities in lungs, kidneys, and spleen versus vehicle control, and demonstrated significantly increased efficacy when combined with meropenem (vs either agent alone). Conclusions CF-370 is the first engineered lysin described with potent broad-spectrum in vitro activity against multiple clinically relevant gram-negative pathogens, as well as potent in vivo efficacy in an animal model of severe invasive multisystem infection. [ABSTRACT FROM AUTHOR]

Background: Food-associated antibiotic-resistant bacteria can cause infections that may critically impact human health. The objectives of this study were to determine the microbial contamination level of green leafy vegetables and their antibiotic resistance pattern. Methods: Sixty-three samples of leafy vegetables were collected from Dammam Central Fruit and Vegetables Market from January to June 2023. The vegetables included lettuce (Lactuca sativa), parsley (Petroselinum crispum), and watercress (Nasturtium officinale). Samples were tested by standard microbiological techniques for identification and antibiotic susceptibility testing. Result: Eight types of bacteria belonging to six different genera were detected. Enterobacteriaceae family was represented by four genera: Klebsiella, Proteus, Morganella, and Enterobacter. The other two genera were Pseudomonas and Aeromonas. Enterobacter cloacae was the most abundant organism, followed by Pseudomonas putida and Aeromonas sobria. On the other hand, Morganella morganii, Aeromonas hydrophila, and Proteus mirabilis were the least abundant. The three vegetable types had different levels of bacterial contamination. All isolated organisms were sensitive to penicillin, cephalosporin, aminoglycoside, and fluoroquinolone. However, Klebsiella oxytoca, M. morganii, and K. pneumonia showed resistance to ampicillin. A. hydrophila, Morganella morganii, and E. cloacae showed resistance to amoxicillin. M. morganii and E. cloacae were found to be resistant to cefalotin. Moreover, A. hydrophila, M. morganii, and E. cloacae were resistant to cefoxitin. Again, A. hydrophila was found to be resistant to imipenem. Only M. morganii was resistant to Ciprofloxacin. Two isolates, P. mirabilis and M. morganii were resistant to tigecycline. Another two, M. morganii and P. mirabilis were resistant to Nitrofurantoin. Only M. morganii was found to be resistant to trimethoprim. Conclusion: This study aligns with the broad consensus in the literature about the significance of bacterial contamination in vegetables and the public health implications. The unique focus on antibiotic resistance patterns adds an essential dimension to the existing body of knowledge. [ABSTRACT FROM AUTHOR]

Novel 1,2,3‐triazole acetamide linked quinazolinone derivatives were synthesized via click reaction, by reacting of 3‐methyl‐2‐(prop‐2‐yn‐1‐ylthio)quinazolin‐4(3H)‐one with various aryl azides as prominent fungal pathogen Candida albicans interactions. The prepared triazole compounds were characterized using mass spectrometry, 1H NMR, 13C NMR, and IR spectroscopic techniques. Compounds were screened for their in vitro antibacterial and antifungal activity against a variety of microorganisms namely, Bacillus subtilis, Enterococcus faecalis, Klebsiella pneumonia, Escherichia coli, Aspergillus fumigatus, Candida albicans, and Aspergillus clavatus. Quinazolinone linked p‐hydroxyphenyl, o, p‐dihydroxyphenyl and o‐dimethylamino phenyl triazoles showed a remarkable antibacterial activity against E. faecalis with MIC values of 3.20±0.01, 4.01±0.04, and 4.10±0.01 μg mL−1, and screened compounds p‐nitrophenyl substituted triazole, and p‐methylphenyl substituted triazole displayed a significant antifungal activity against C. albicans with MICs of 3.16±0.01, 4.06±0.03 μg mL−1, compared to itraconazole (MIC=3.32±0.02 μg mL−1). For further exploration of the anti‐fungal mechanism of action, molecular docking was carried out for these compounds in C. albicans active site as one of the important antifungal inhibitors (PDB: 1A19). Furthermore, the ADMET profile was evaluated for all the final triazole compounds in contrast to reference drugs moxifloxacin and itraconazole. In conclusion, we discovered a novel quinazolinone linked 1,2,3‐triazoles with promising antimicrobial activity and a favorable pharmacokinetic profile. [ABSTRACT FROM AUTHOR]

Background: In the hospital environment, carbapenemase-producing Pseudomonas aeruginosa (CPPA) may lead to fatal patient infections. However, the transmission routes of CPPA often remain unknown. Therefore, this case study aimed to trace the origin of CPPA ST357, which caused a hospital-acquired pneumonia in a repatriated critically ill patient suffering from Guillain-Barré Syndrome in 2023. Methods: Antimicrobial susceptibility of the CPPA isolate for 30 single and combination therapies was determined by disk-diffusion, Etest or broth microdilution. Whole-genome sequencing was performed for three case CPPA isolates (one patient and two sinks) and four distinct CPPA ST357 patient isolates received in the Dutch CPPA surveillance program. Furthermore, 193 international P. aeruginosa ST357 assemblies were collected via three genome repositories and analyzed using whole-genome multi-locus sequence typing in combination with antimicrobial resistance gene (ARG) characterization. Results: A Dutch patient who carried NDM-1-producing CPPA was transferred from Kenya to the Netherlands, with subsequent dissemination of CPPA isolates to the local sinks within a month after admission. The CPPA case isolates presented an extensively drug-resistant phenotype, with susceptibility only for colistin and cefiderocol-fosfomycin. Phylogenetic analysis showed considerable variation in allelic distances (mean = 150, max = 527 alleles) among the ST357 isolates from Asia (n = 92), Europe (n = 58), Africa (n = 21), America (n = 16), Oceania (n = 2) and unregistered regions (n = 4). However, the case isolates (n = 3) and additional Dutch patient surveillance program isolates (n = 2) were located in a sub-clade of isolates from Kenya (n = 17; varying 15–49 alleles), the United States (n = 7; 21–115 alleles) and other countries (n = 6; 14–121 alleles). This was consistent with previous hospitalization in Kenya of 2/3 Dutch patients. Additionally, over half of the isolates (20/35) in this sub-clade presented an identical resistome with 9/17 Kenyan, 5/5 Dutch, 4/7 United States and 2/6 other countries, which were characterized by the blaNDM-1, aph(3')-VI, ARR-3 and cmlA1 ARGs. Conclusion: This study presents an extensively-drug resistant subclone of NDM-producing P. aeruginosa ST357 with a unique resistome which was introduced to the Netherlands via repatriation of critically ill patients from Kenya. Therefore, the monitoring of repatriated patients for CPPA in conjunction with vigilance for the risk of environmental contamination is advisable to detect and prevent further dissemination. [ABSTRACT FROM AUTHOR]

Background: Infections resulting from multidrug-resistant Enterobacterales (MDR-E) pose a growing global threat, presenting challenges in treatment and contributing significantly to morbidity and mortality rates. The main objective of this study was to characterize phenotypically and genetically extended-spectrum β-lactamase- and carbapenemase- producing Enterobacterales (ESBLE and CPE respectively) isolated from clinical samples in the West Bank, Palestine. Methods: A cross sectional study was conducted in October 2023 on clinical bacterial isolates collected from five governmental hospitals in the West Bank, Palestine. The isolates obtained from the microbiology laboratories of the participating hospitals, underwent identification and antibiotic susceptibility testing (AST) using the VITEK® 2 Compact system. ESBL production was determined by the Vitek2 Compact system. A modified carbapenem inactivation method (mCIM) was employed to identify carbapenemase-producing Enterobacterales (CPE). Resistance genes were detected by real-time PCR. Results: Out of the total 1380 collected isolates, we randomly selected 600 isolates for analysis. Our analysis indicated that 287 (47.83%) were extended-spectrum beta-lactamase producers (ESBLE), and 102 (17%) as carbapenem-resistant Enterobacterales (CRE) isolates. A total of 424 isolates (70.67%) were identified as multidrug-resistant Enterobacterales (MDRE). The most prevalent ESBL species were K. pneumoniae (n = 124; 43.2%), E. coli (n = 119; 41.5%) and E. cloacae (n = 31; 10.8%). Among the CRE isolates, 85 (83.33%) were carbapenemase-producing Enterobacterales (CPE). The most frequent CRE species were K. pneumoniae (n = 63; 61.7%), E. coli (n = 25; 24.5%) and E. cloacae (n = 13; 12.8%). Additionally, 47 (7.83%) isolates exhibited resistance to colistin (CT), with 38 (37.62%) being CT-resistant CRE and 9 (3.14%) being CT-resistant ESBLE while sensitive to carbapenems. We noticed that 11 isolates (6 Klebsiella pneumoniae and 5 Enterobacter cloacae complex) demonstrated sensitivity to carbapenems by phenotype but carried silent CPE genes (1 blaOXA48, and 6 blaNDM, 4 blaOXA48, blaNDM). ESBL-producing Enterobacterales strains exhibited varied resistance patterns across different antibiotic classes. E. coli isolates showed notable 48% resistance to trimethoprim/sulfamethoxazole. K. pneumoniae isolates displayed a significant resistance to trimethoprim/sulfamethoxazole, nitrofurantoin, and fosfomycin (54%, 90%, and 70% respectively). E. cloacae isolates showed complete resistance to nitrofurantoin and fosfomycin. P. mirabilis isolates exhibited high resistance against fluoroquinolones (83%), and complete resistance to trimethoprim/sulfamethoxazole, nitrofurantoin and fosfomycin. Conclusion: This study showed the high burden of the ESBLE and CRE among the samples collected from the participating hospitals. The most common species were K. pneumoniae and E. coli. There was a high prevalence of blaCTXm. Adopting both conventional and molecular techniques is essential for better surveillance of the emergence and spread of antimicrobial-resistant Enterobacterales infections in Palestine. [ABSTRACT FROM AUTHOR]

Background: Cockroaches can pose a significant health risk in hospital environments because they may serve as reservoirs and vectors for nosocomial pathogens. Cockroaches harbor epidemiologically significant extended spectrum and metalo beta lactamase producing Gram negative bacterial pathogens, which complicate nosocomial infections. Objectives: The main aim of this study is to determine aetiology and phenotypic extended spectrum and metalo beta lactamase producing Gram negative bacteria pathogens from cockroaches collected in hospitals. Methods: A cross-sectional study was employed from February to May 2022 to determine the antibiotic resistance producing bacterial isolates from cockroaches by giving special emphasis to metalo beta lactamase and extended spectrum beta lactamase production from different wards of WSUCSH. Cockroaches were collected with hands wearing sterile gloves. External homogenate was prepared and incubated microbiologically by using different culture media and differentiated biochemically. Antimicrobial susceptibility testing was performed by disk diffusion method. ESBL production was conducted using double disc synergy method and double disk method was used to detect MBL enzyme detection. Descriptive statistics was used to determine prevalence and percentage. Result: Out of 245 cockroaches, 108 Gram negative bacteria were isolated. K. pneumoniae 29(26.9%) was the most predominant bacteria and Enetrobacter spp. 8(7.4%), was the least. All, K. pneumoniae, P. mirabilis, and Enterobacter isolates were pan-resistant to Ampicillin. P.aeruginosa and P.mirabilis antibiotics showed ≥ 80% resistant for amoxicillin/clavulanic acid antibiotics. Cefotaxime, ceftazidime, ceftriaxone and imipenem showed relative efficacy compared with other antibiotics. Out of 78 amoxicillin-clavulanic acid resistant isolates, 42(34.7%) were ESBL producers. ESBL production is more depicted by P. aeruginosa, A. baumannii, K. pneumoniae and E. coli. The overall prevalence of MBL production is 29(23.1%). K. pneumoniae P. aeruginosa, E.coli, A. baumannii, Enterobacter spp and K.oxytoca revealed MBL production. Conclusion: The overall prevalence of ESBL and MBL producing nosocomial agents from hospital cockroaches was 34.7% and 23.1% respectively. P.aeruginosa, A.baumannii, K.pneumoniae and E.coli showed pronounced ESBL production. All bacterial isolates except P. mirabilis and C. freundii showed MBL production. The needed to evaluate our antibiotic stewardship program and antibiotic resistance detection for treatment is mandatory. The impact of cockroach as a source of AMR should be sought. [ABSTRACT FROM AUTHOR]

Bloodstream infections caused by the opportunistic pathogen Klebsiella pneumoniae are associated with adverse health complications and high mortality rates. Antimicrobial resistance (AMR) limits available treatment options, thus exacerbating its public health and clinical burden. Here, we aim to elucidate the population structure of K. pneumoniae in bloodstream infections from a single medical center and the drivers that facilitate the dissemination of AMR. Analysis of 136 short-read genome sequences complemented with 12 long-read sequences shows the population consisting of 94 sequence types (STs) and 99 clonal groups, including globally distributed multidrug resistant and hypervirulent clones. In vitro antimicrobial susceptibility testing and in silico identification of AMR determinants reveal high concordance (90.44–100%) for aminoglycosides, beta-lactams, carbapenems, cephalosporins, quinolones, and sulfonamides. IncF plasmids mediate the clonal (within the same lineage) and horizontal (between lineages) transmission of the extended-spectrum beta-lactamase gene blaCTX-M-15. Nearly identical plasmids are recovered from isolates over a span of two years indicating long-term persistence. The genetic determinants for hypervirulence are carried on plasmids exhibiting genomic rearrangement, loss, and/or truncation. Our findings highlight the importance of considering both the genetic background of host strains and the routes of plasmid transmission in understanding the spread of AMR in bloodstream infections. Authors perform a genomic analyses of 136 Klebsiella pneumoniae isolates, revealing that both the genetic background of host strains and the routes of plasmid transmission influence the spread of antimicrobial resistance in bloodstream infections. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae is an opportunistic bacterium that frequently colonizes the nasopharynx and gastrointestinal tract and can also cause severe infections when invading other tissues, particularly in immunocompromised individuals. Moreover, K. pneumoniae variants exhibiting a hypermucoviscous (HMV) phenotype are usually associated with hypervirulent strains that can produce invasive infections even in immunocompetent individuals. Major carbohydrate structures displayed on the K. pneumoniae surface are the polysaccharide capsule and the lipopolysaccharide, which presents an O-polysaccharide chain in its outermost part. Various capsular and O-chain structures have been described. Of note, production of a thick capsule is frequently observed in HMV variants. Here we examined the surface sugar epitopes of a collection of HMV and non-HMV K. pneumoniae clinical isolates and their recognition by several Siglecs and galectins, two lectin families of the innate immune system, using bacteria microarrays as main tool. No significant differences among isolates in sialic acid content or recognition by Siglecs were observed. In contrast, analysis of the binding of model lectins with diverse carbohydrate-binding specificities revealed striking differences in the recognition by galactose- and mannose-specific lectins, which correlated with the binding or lack of binding of galectins and pointed to the O-chain as the plausible ligand. Fluorescence microscopy and microarray analyses of galectin-9 binding to entire cells and outer membranes of two representative HMV isolates supported the bacteria microarray results. In addition, Western blot analysis of the binding of galectin-9 to outer membranes unveiled protein bands recognized by this galectin, and fingerprint analysis of these bands identified several proteins containing potential O-glycosylation sites, thus broadening the spectrum of possible galectin ligands on the K. pneumoniae surface. Moreover, Siglecs and galectins apparently target different structures on K. pneumoniae surfaces, thereby behaving as nonredundant complementary tools of the innate immune system. [ABSTRACT FROM AUTHOR]

Introduction: In the battle against multidrug-resistant bacterial infections, ceftazidime- avibactam (CZA) stands as a pivotal defense, particularly against carbapenemresistant (CR) Gram-negative pathogens. However, the rise in resistance against this drug poses a significant threat to its effectiveness, highlighting the critical need for in-depth studies about its resistance mechanisms. Methods: This research focuses on the genomic characterization of CR- and CZA-resistant Escherichia coli (n=26) and Klebsiella pneumoniae (n=34) strains, harboring the blaNDM and/or blaOXA-48-like genes, at a major Lebanese tertiary care medical center, using whole genome sequencing (WGS). Results: Our findings revealed a notable prevalence of blaNDM in all K. pneumoniae strains isolates, with 27 of these also harboring blaOXA-48.On the other hand, E. coli strains predominantly carried the blaNDM-5 gene. Whole genome sequencing (WGS) identified a predominance of ST383 among K. pneumoniae strains, which possessed a multi-replicon IncFIB-IncHI1B plasmid harboring the blaNDM-5. Additionally, various Inc group plasmids in K. pneumoniae across multiple sequence types were found to carry the blaNDM. Similarly, diverse STs of E. coli were observed to carry blaNDM-5 on different plasmids. Discussion: The study underscores NDM carbapenemases as a paramount resistance mechanism in Lebanon,jeopardizing critical last-resort treatments. It also illuminates the role of varied sequence types and mobile genetic elements in the spread of NDM resistance,stressing the urgent need for strategies to mitigate this threat, especially in nosocomial infections. [ABSTRACT FROM AUTHOR]

Hypervirulent Klebsiella pneumoniae (HvKP) is an emerging bacterial pathogen causing invasive infection in immune-competent humans. The hypervirulence is strongly linked to the overproduction of hypermucoviscous capsule, but the underlying regulatory mechanisms of hypermucoviscosity (HMV) have been elusive, especially at the post-transcriptional level mediated by small noncoding RNAs (sRNAs). Using a recently developed RNA interactome profiling approach iRIL-seq, we interrogate the Hfq-associated sRNA regulatory network and establish an intracellular RNA-RNA interactome in HvKP. Our data reveal numerous interactions between sRNAs and HMV-related mRNAs, and identify a plethora of sRNAs that repress or promote HMV. One of the strongest HMV repressors is ArcZ, which is activated by the catabolite regulator CRP and targets many HMV-related genes including mlaA and fbp. We discover that MlaA and its function in phospholipid transport is crucial for capsule retention and HMV, inactivation of which abolishes Klebsiella virulence in mice. ArcZ overexpression drastically reduces bacterial burden in mice and reduces HMV in multiple hypervirulent and carbapenem-resistant clinical isolates, indicating ArcZ is a potent RNA inhibitor of bacterial pneumonia with therapeutic potential. Our work unravels a novel CRP-ArcZ-MlaA regulatory circuit of HMV and provides mechanistic insights into the posttranscriptional virulence control in a superbug of global concern. By performing a global RNA-RNA interactome analysis in hypervirulent Klebsiella pneumoniae, the authors identify the small RNA ArcZ targets many capsule genes and a key virulence factor MlaA, inhibiting Klebsiella infection and pathogenesis in mice. [ABSTRACT FROM AUTHOR]

Background: Klebsiella pneumoniae is a zoonotic opportunistic pathogen, and also one of the common pathogenic bacteria causing mink pneumonia. The aim of this study was to get a better understanding of the whole-genome of multi-drug resistant Klebsiella pneumoniae with K2 serotype in China. This study for the first time to analyze Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, resistance and virulence genes of Klebsiella pneumoniae in mink. Results: The isolate was Klebsiella pneumoniae with serotype K2 and ST6189 by PCR method. The string test was positive and showed high mucus phenotype. There was one plasmid with IncFIB replicons in the genome. The virulence factors including capsule, lipopolysaccharide, adhesin, iron uptake system, urease, secretory system, regulatory gene (rcsA, rcsB), determinants of pili adhesion, enolase and magnesium ion absorption related genes. The strain was multi-drug resistant. A total of 26 resistance genes, including beta-lactam, aminoglycosides, tetracycline, fluoroquinolones, sulfonamides, amide alcohols, macrolides, rifampicin, fosfomycin, vancomycin, diaminopyrimidines and polymyxin. Multidrug-resistant efflux protein AcrA, AcrB, TolC, were predicted in the strain. Conclusion: It was the first to identify that serotype K2 K. pneumonia with ST6189 isolated from mink in China. The finding indicated that hypervirulent and multi-drug resistant K. pneumoniae was exist in Chinese mink. The whole-genome of K. pneumoniae isolates have importance in mink farming practice. [ABSTRACT FROM AUTHOR]

Polymyxin B (PMB) is often considered as the last line of defense for treating carbapenem‐resistant Klebsiella pneumoniae (CRKP). However, its efficacy is hindered by limited penetration across the blood‐air barrier in the lung due to its low lipid solubility. To simultaneously increase PMB in epithelial lining fluid while suppressing the excessive inflammatory response in the lung, a novel nano‐biomimetic system "Siv‐PMB@G4@MM" is designed and fabricated by encapsulating PMB‐ and anti‐inflammatory Sivelestat (Siv)‐loaded G4 PAMAM dendrimers with macrophage membranes (MM). The Siv‐PMB@G4@MM displayed a superior acidic pH‐responsive release property and can target inflamed lung tissues, greatly increasing the concentrations of PMB and Siv at the infection site. Compared with free drugs, Siv‐PMB@G4@MM demonstrated superior synergistic antibacterial and anti‐inflammatory activities. Moreover, due to the ability of MM to sequester lipopolysaccharide (LPS) and some pro‐inflammatory cytokines, Siv‐PMB@G4@MM further enhanced the anti‐inflammatory potential of Siv. In mouse models of LPS‐induced acute lung injury, pulmonary bacterial infection, and sepsis‐induced pneumonia, Siv‐PMB@G4@MM significantly reduced inflammatory responses and/or bacterial burdens, mitigated neutrophil infiltration and pulmonary edema, and decreased neutrophil extracellular trap (NET) secretion. The highly improved biocompatibility and efficiency of the multifunctional Siv‐PMB@G4@MM presents a promising strategy for the clinical treatment of antibiotic‐resistant bacterial pneumonia. [ABSTRACT FROM AUTHOR]

β-lactam resistance is a significant global public health issue. Outbreaks of bacteria resistant to extended-spectrum β-lactams and carbapenems are serious health concerns that not only complicate medical care but also impact patient outcomes. The primary objective of this work was to express and purify two soluble recombinant representative serine β‑lactamases using Escherichia coli strain as an expression host and pET101/D as a cloning vector. Furthermore, a second objective was to evaluate the potential, innovative, and safe use of galloylquinic acid (GQA) from Copaifera lucens as a potential β-lactamase inhibitor. In the present study, blaCTX-M-15 and blaKPC-2 represented genes encoding for serine β-lactamases that were cloned from parent isolates of E. coli and K. pneumoniae, respectively, and expression as well as purification were performed. Moreover, susceptibility results demonstrated that recombinant cells became resistant to all test carbapenems (MICs; 64–128 µg/mL) and cephalosporins (MICs; 128–512 µg/mL). The MICs of the tested β-lactam antibiotics were determined in combination with 4 µg/mL of GQA, clavulanic acid, or tazobactam against E. coli strains expressing CTX-M-15 or KPC-2-β-lactamases. Interestingly, the combination with GQA resulted in an important reduction in the MIC values by 64–512-fold to the susceptible range with comparable results for other reference inhibitors. Additionally, the half-maximal inhibitory concentration of GQA was determined using nitrocefin as a β-lactamase substrate. Data showed that the test agent was similar to tazobactam as an efficient inhibitors of the test enzymes, recording smaller IC50 values (CTX-M-15; 17.51 for tazobactam, 28.16 µg/mL for GQA however, KPC-2; 20.91 for tazobactam, 24.76 µg/mL for GQA) compared to clavulanic acid. Our work introduces GQA as a novel non-β-lactam inhibitor, which interacts with the crucial residues involved in β-lactam recognition and hydrolysis by non-covalent interactions, complementing the enzyme's active site. GQA markedly enhanced the potency of β-lactams against carbapenemase and extended-spectrum β-lactamase-producing strains, reducing the MICs of β-lactams to the susceptible range. The β-lactamase inhibitory activity of GQA makes it a promising lead molecule for the development of more potent β-lactamase inhibitors. [ABSTRACT FROM AUTHOR]

Extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) is regarded as one of the most important priority pathogens within the One Health interface. However, few studies have investigated the occurrence of ESBL-EC in giant pandas, along with their antibiotic-resistant characteristics and horizontal gene transfer abilities. In this study, we successfully identified 12 ESBL-EC strains (8.33%, 12/144) out of 144 E. coli strains which isolated from giant pandas. We further detected antibiotic resistance genes (ARGs), virulence-associated genes (VAGs) and mobile genetic elements (MGEs) among the 12 ESBL-EC strains, and the results showed that 13 ARGs and 11 VAGs were detected, of which blaCTX-M (100.00%, 12/12, with 5 variants observed) and papA (83.33%, 10/12) were the most prevalent, respectively. And ISEcp1 (66.67%, 8/12) and IS26 (66.67%, 8/12) were the predominant MGEs. Furthermore, horizontal gene transfer ability analysis of the 12 ESBL-EC showed that all blaCTX-M genes could be transferred by conjugative plasmids, indicating high horizontal gene transfer ability. In addition, ARGs of rmtB and sul2, VAGs of papA, fimC and ompT, MGEs of ISEcp1 and IS26 were all found to be co-transferred with blaCTX-M. Phylogenetic analysis clustered these ESBL-EC strains into group B2 (75.00%, 9/12), D (16.67%, 2/12), and B1 (8.33%, 1/12), and 10 sequence types (STs) were identified among 12 ESBL-EC (including ST48, ST127, ST206, ST354, ST648, ST1706, and four new STs). Our present study showed that ESBL-EC strains from captive giant pandas are reservoirs of ARGs, VAGs and MGEs that can co-transfer with blaCTX-M via plasmids. Transmissible ESBL-EC strains with high diversity of resistance and virulence elements are a potential threat to humans, animals and surrounding environment. [ABSTRACT FROM AUTHOR]

Arguably, the greatest threat to bacteria is phages. It is often assumed that those bacteria that escape phage infection have mutated or utilized phage‐defence systems; however, another possibility is that a subpopulation forms the dormant persister state in a manner similar to that demonstrated for bacterial cells undergoing nutritive, oxidative, and antibiotic stress. Persister cells do not undergo mutation and survive lethal conditions by ceasing growth transiently. Slower growth and dormancy play a key physiological role as they allow host phage defence systems more time to clear the phage infection. Here, we investigated how bacteria survive lytic phage infection by isolating surviving cells from the plaques of T2, T4, and lambda (cI mutant) virulent phages and sequencing their genomes. We found that bacteria in plaques can escape phage attack both by mutation (i.e. become resistant) and without mutation (i.e. become persistent). Specifically, whereas T4‐resistant and lambda‐resistant bacteria with over a 100,000‐fold less sensitivity were isolated from plaques with obvious genetic mutations (e.g. causing mucoidy), cells were also found after T2 infection that undergo no significant mutation, retain wild‐type phage sensitivity, and survive lethal doses of antibiotics. Corroborating this, adding T2 phage to persister cells resulted in 137,000‐fold more survival compared to that of addition to exponentially growing cells. Furthermore, our results seem general in that phage treatments with Klebsiella pneumonia and Pseudomonas aeruginosa also generated persister cells. Hence, along with resistant strains, bacteria also form persister cells during phage infection. [ABSTRACT FROM AUTHOR]

Infections that are acquired due to a prolonged hospital stay and manifest 2 days following the admission of a patient to a health-care institution can be classified as hospital-acquired infections. Klebsiella pneumoniae (K. pneumoniae) has become a critical pathogen, posing serious concern globally due to the rising incidences of hypervirulent and carbapenem-resistant strains. Glutaredoxin is a redox protein that protects cells from oxidative stress as it associates with glutathione to reduce mixed disulfides. Protein adenylyltransferase (PrAT) is a pseudokinase with a proposed mechanism of transferring an AMP group from ATP to glutaredoxin. Inducing oxidative stress to the bacterium by inhibiting the activity of PrAT is a promising approach to combating its contribution to hospital-acquired infections. Thus, this study aims to overexpress, purify, and analyse the effects of ATP and Mg2+ binding to Klebsiella pneumoniae PrAT (KpPrAT). The pET expression system and nickel affinity chromatography were effective in expressing and purifying KpPrAT. Far-UV CD spectroscopy demonstrates that the protein is predominantly α-helical, even in the presence of Mg2+. Extrinsic fluorescence spectroscopy with ANS indicates the presence of a hydrophobic pocket in the presence of ATP and Mg2+, while mant-ATP studies allude to the potential nucleotide binding ability of KpPrAT. The presence of Mg2+ increases the thermostability of the protein. Isothermal titration calorimetry provides insight into the binding affinity and thermodynamic parameters associated with the binding of ATP to KpPrAT, with or without Mg2+. Conclusively, the presence of Mg2+ induces a conformation in KpPrAT that favours nucleotide binding. [ABSTRACT FROM AUTHOR]

Background and Objectives: Today, medicinal plants and their derivatives are considered to reduce the prevalence of antibiotic resistance. The aim of this study was to investigate the effect of Mentha longifolia essential oil on oqxA efflux pump gene expression and biofilm formation in ciprofloxacin-resistant Klebsiella pneumoniae strains. Materials and Methods: A total of 50 clinical strains of K. pneumoniae resistant to ciprofloxacin were studied. The minimum inhibitory concentration (MIC) of M. longifolia essential oil and its synergistic effect with ciprofloxacin were determined using the microbroth dilution method and the fractional inhibitory concentration (FIC) method. Minimum biofilm inhibition concentration (MBIC) of M. longifolia essential oil was detected. The effect of essential oils on the expression level of the oqxA gene was detected by Real-time PCR. Results: M. longifolia essential oil showed inhibitory activity against ciprofloxacin-resistant strains of K. pneumoniae. When M. longifolia essential oil was combined with ciprofloxacin, the MIC was reduced 2-4 times. In 28% of the strains, M. longifolia with ciprofloxacin showed a synergistic effect. M. longifolia essential oil reduces the strength of biofilm formation and alters the biofilm phenotype. A significant decrease in oqxA gene expression was observed in all isolates after treatment with M. longifolia essential oil. Conclusion: Based on the results of this study, it was observed that supplementing M. longifolia essential oil can help reduce ciprofloxacin resistance and inhibit biofilm formation in fluoroquinolone-resistant K. pneumoniae strains. [ABSTRACT FROM AUTHOR]

Antibiotic resistance has become a global threat as it is continuously growing due to the evolution of β‐lactamases diminishing the activity of classic β‐lactam (BL) antibiotics. Recent antibiotic discovery and development efforts have led to the availability of β‐lactamase inhibitors (BLIs) with activity against extended‐spectrum β‐lactamases as well as Klebsiella pneumoniae carbapenemase (KPC)‐producing carbapenem‐resistant organisms (CRO). Nevertheless, there is still a lack of drugs that target metallo‐β‐lactamases (MBL), which hydrolyze carbapenems efficiently, and oxacillinases (OXA) often present in carbapenem‐resistant Acinetobacter baumannii. This review aims to provide a snapshot of microbiology, pharmacology, and clinical data for currently available BL/BLI treatment options as well as agents in late stage development for CRO harboring various β‐lactamases including MBL and OXA‐enzymes. [ABSTRACT FROM AUTHOR]

The study determined the prevalence, antimicrobial resistant (AMR) determinants, and genetic characteristics of Escherichia coli and Klebsiella pneumoniae isolates from patients with diabetic foot infection (DFI) in a Tunisian hospital. A total of 26 Escherichia spp. and Klebsiella spp. isolates were recovered and identified by MALDI-TOF-MS. Antimicrobial susceptibility testing, the detection of AMR determinants and Shiga-like toxin genes, phylogenetic grouping, and molecular typing were performed. Twelve E. coli, 10 K. pneumoniae, 3 K. oxytoca, and 1 E. hermanii were isolated. A multidrug-resistant phenotype was detected in 65.4% of the isolates. About 30.8% of isolates were extended-spectrum β-lactamase (ESBL) producers and mainly carried blaCTX-M-15 and blaCTX-M-14 genes. One blaNDM-1-producing K. pneumoniae-ST1 strain was identified. Class 1 integrons were detected in 11 isolates and 5 gene cassette arrangements were noted: dfrA1+aadA1 (n = 1), dfrA12+aadA2 (n = 3), and dfrA17+aadA5 (n = 1). Other non-β-lactam resistance genes detected were as follows (number of isolates): aac(3')-II (3), aac(6')–Ib-cr(8), qnrB (2), qnrS (4), cmlA (2), floR (4), sul1 (11), sul2 (11), and sul3 (2). The phylogroup B1 was the most frequent (41.7%) among E. coli, and two ESBL-producing isolates corresponded to the ST131-B2 lineage. The ESBL- and carbapenemase-producing Enterobacteriaceae in DFIs are described for the first time in Tunisia. [ABSTRACT FROM AUTHOR]

The emergence of carbapenemase-producing Klebsiella pneumoniae poses a substantial risk to public health. It is essential to comprehend the influence of carbapenemase on the virulence characteristics of K. pneumoniae in order to devise successful strategies for combating these infections. In this study, we explored the distribution disparity of virulence determinants between carbapenemase-producing (CP-Kp, n = 52) and carbapenemase-nonproducing (CN-Kp, n = 43) isolates. The presence of carbapenemases was detected via the modified carbapenem inactivation method and confirmed by PCR. The New Delhi metallo-β-lactamase (blaNDM) and Oxacillinase-48-like (blaOXA-48-like) genes were the most prevalent (94.23% and 76.92%, respectively) in CP-Kp isolates. Coexistence of blaNDM and blaOXA-48-like was observed in 71.15% of isolates, whereas 5.77% coharbored blaNDM and blaKPC. PCR analysis revealed the presence of several virulence genes, including adhesins (fimH, 92.63%, mrkD, 97.89%), capsule-associated virulence (uge, 90.53%), the K2 capsule serotype (k2, 6.32%), the iron acquisition system (kfu, 23.16%), and the regulator of mucoid phenotype (rmpA, 28.42%). A significantly higher prevalence of rmpA was detected in the CP-Kp compared with the CN-Kp (24/52 vs. 3/43, p < 0.0001), indicating a potential association between rmpA and carbapenemase acquisition. In addition, the majority of rmpA (22/24) positive isolates in the CP-Kp isolates coharbored blaNDM and either blaOXA-48-like or blaKPC. [ABSTRACT FROM AUTHOR]

This study assessed prognostic factors and the role of vitrectomy in patients with subretinal abscesses secondary to K. pneumoniae endophthalmitis. We reviewed published studies, including three cases from our cohort. Among 50 eyes, 26 had poor visual outcomes (final visual acuity <20/800, eyeball removal, or phthisis bulbi). Poor outcomes correlated with delayed ocular symptom-to-diagnosis time, initial visual acuity <20/800, severe vitritis, and macular involvement of abscesses (p < 0.001, p = 0.008, p < 0.001, and p = 0.033, respectively). Vitrectomy had a trend towards reducing eyeball removal and phthisis bulbi rates compared with non-vitrectomy (10.8% vs 30.8%, p = 0.181). However, the final visual acuity was not different and the rate of retinal detachment tended to be higher in vitrectomized eyes (45.9% vs 15.4%, p = 0.095). The study suggested that vitrectomy and drainage of K. pneumoniae subretinal abscesses could be avoided in patients with a mild degree of vitritis. [ABSTRACT FROM AUTHOR]

To investigate the etiology, pathogens, treatment, and prognosis of endogenous endophthalmitis (EE). Patients diagnosed with EE over three decades at Peking Union Medical College Hospital were retrospectively reviewed and analyzed. A total of 97 eyes from 81 patients were included. Diabetes was the most common predisposing medical condition (34.6%). Klebsiella pneumoniae (31.3%) and Candida albicans (32.8%) were the most common pathogens. Liver abscess (20.6%) was the predominant cause EE due to liver abscess had a worse initial visual acuity (P < 0.05). Patients who initially underwent pars plana vitrectomy (PPV)+silicone oil tamponade underwent fewer total treatments (P < 0.05). In the past 10 years, the proportion of Gram-positive cocci, Gram-negative bacilli, and Candida showed an upward trend. Over the past 15 years, EE after liver abscess and immunosuppression has increased, while EE from genitourinary systems has decreased. EE was a devastating intraocular disease with a poor visual prognosis. The initial condition and prognosis of EE after liver abscess were the worst. PPV+silicone oil tamponade as an initial treatment may reduce additional therapy. [ABSTRACT FROM AUTHOR]

To investigate the clinical features of endogenous Klebsiella pneumoniae endophthalmitis (EKPE) and the molecular characteristics of pathogenic K. pneumoniae. A retrospective study was conducted between January 2014 and January 2021. Clinical data were extracted. K. pneumoniae isolates cultured from EKPE patients' specimens were characterized by antimicrobial susceptibility testing, multilocus sequence typing, capsular serotyping, and virulence gene profiles. Virulence phenotypes were confirmed by mouse lethality assay. Thirty-nine patients (47 eyes) were diagnosed with EKPE. Administration of systemic antibiotics and eye treatment within 24 hours of ocular symptom onset was statistically associated with better visual outcomes (p =.007). Sixteen K. pneumoniae isolates were collected, three of which were carbapenem-resistant and avirulent. Only salmochelin encoding gene was harbored by all isolates. Systemic and eye treatment administered within 24 hours from the onset improves visual prognosis. Besides hypervirulent strains, avirulent carbapenem-resistant K. pneumoniae can cause EKPE. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae (Kp) is an infectious disease pathogen that poses a significant global health threat due to its potential to cause severe infections and its tendency to exhibit multidrug resistance. Understanding the enzymatic mechanisms of the oxygen‐insensitive nitroreductases (Kp‐NRs) from Kp is crucial for the development of effective nitrofuran drugs, such as nitrofurantoin, that can be activated as antibiotics. In this paper, three crystal structures of two Kp‐NRs (PDB entries 7tmf/7tmg and 8dor) are presented, and an analysis of their crystal structures and their flavin mononucleotide (FMN)‐binding mode is provided. The structures with PDB codes 7tmf (Kp‐NR1a), 7tmg (Kp‐NR1b) and 8dor (Kp‐NR2) were determined at resolutions of 1.97, 1.90 and 1.35 Å, respectively. The Kp‐NR1a and Kp‐NR1b structures adopt an αβ fold, in which four‐stranded antiparallel β‐sheets are surrounded by five helices. With domain swapping, the β‐sheet was expanded with a β‐strand from the other molecule of the dimer. The difference between the structures lies in the loop spanning Leu173–Ala185: in Kp‐NR1a the loop is disordered, whereas the loop adopts multiple conformations in Kp‐NR1b. The FMN interactions within Kp‐NR1/NR2 involve hydrogen‐bond and π‐stacking interactions. Kp‐NR2 contains four‐stranded antiparallel β‐sheets surrounded by eight helices with two short helices and one β‐sheet. Structural and sequence alignments show that Kp‐NR1a/b and Kp‐NR2 are homologs of the Escherichia coli oxygen‐insensitive NRs YdjA and NfnB and of Enterobacter cloacae NR, respectively. By homology inference from E. coli, Kp‐NR1a/b and Kp‐NR2 may detoxify polynitroaromatic compounds and Kp‐NR2 may activate nitrofuran drugs to cause bactericidal activity through a ping‐pong bi‐bi mechanism, respectively. [ABSTRACT FROM AUTHOR]