Microbial drug resistance最新文献

Carbapenems are the last-line antibiotic defense against gram-negative extended spectrum β-lactamase producers. Carbapenem-resistant Enterobacteriaceae, especially carbapenem-resistant Klebsiella pneumoniae (CRKP), is recognized as one of the well-known public health problems, which is increasingly being reported around the world. The present study focused on analyzing the carbapenemase-producing K. pneumoniae isolates obtained from patients admitted to the intensive care unit of a tertiary care hospital in Western Uttar Pradesh, India, and the results confirmed the presence of resistant genes using real-time polymerase chain reaction (PCR). A total of 103 K. pneumoniae isolates were screened for carbapenem resistance using the VITEK 2 compact system (bioMérieux SA, Marcy-l'Étoile, France). Carbapenemase was detected using genotypic characterization by real-time PCR; 49.5% of isolates were confirmed as K. pneumoniae, including 64.7% CRKP. The most common carbapenemase genes identified were New Delhi metallo-β-lactamase (bla_NDM; 93.9%), followed by bla_OXA-48 (90.9%) and bla_OXA-23 (69.7%). In conclusion, our study results depict a high prevalence of carbapenemase-producing K. pneumoniae. In conclusion, our findings demonstrate a high prevalence of carbapenemase-producing K. pneumoniae in critically ill patients. As there are no new drugs available and the prevalence varies regionally, real-time PCR probe-based detection of these genes is beneficial for early detection, developing infection control protocols, and promoting appropriate antibiotic use.

Biofilm formation is a key virulence factor in urinary tract infections, and Escherichia coli (E. coli) serves as a prominent causative agent, more resistant to antimicrobial agents. This study focused on isolation and phenotypic and genotypic characterization of E. coli from urine samples on the basis of their biofilm-forming capacity. In the present study, a total of 804 human urine samples were collected from different clinical facilities of Faisalabad. After phenotypic and genotypic affirmation, biofilm forming potential of uropathogenic E. coli (UPEC) was determined by using microtiter plate assay (MPA) and the Congo red agar method. Antimicrobial susceptibility testing was conducted, and a comparison was executed between biofilm formers and non-formers. Biofilm production by the MPA and Congo red agar methods was 88% and 68%, respectively. UPEC isolates showed maximum resistance to amoxicillin-clavulanate (97%), cefoparazone (93%), cefotaxime (91%), and ampicillin (90%). Significant association between resistance to antibiotic and biofilm formation with p value <0.05 was observed in case of piperacillin-tazobactam, imipenem, meropenem, amikacin, norfloxacin, nitrofurantoin, polymyxin B, and nalidixic acid. Biofilm producer strains were progressed for molecular characterization using polymerase chain reaction for biofilm-forming genes including fimH, csgA, bcsA, agn43, papC, and focG, which showed prevalence of 89% (118/132), 87% (116/132), 86% (114/132), 81% (107/132), 47% (61/132), and 33% (43/132), respectively.

Introduction: Uropathogenic Escherichia coli (UPEC) are the most common cause of urinary tract infections (UTI). This study investigated the genetic relatedness, biofilm-forming capacity, and antimicrobial resistance profiles in the extended-spectrum beta-lactamase (ESBL)-producing UPEC collected from children with vesicoureteral reflux (VUR) suffering from UTI. Materials and Methods: In this cross-sectional investigation, a total of 80 nonduplicated UPEC isolates were collected from children afflicted with VUR. Antimicrobial susceptibility testing and phenotypic production of ESBL were conducted according to the Clinical and Laboratory Standards Institute (2023) recommendations. Furthermore, PCR tests were used to detect the presence of ESBL genes. Biofilm formation in 96-well microtiter plates was assessed. Finally, the clonal diversity of the isolates was examined using the Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR. Results: Out of all collected isolates, 71.2% (n = 57/80) were ESBL producers and 31.2% (n = 25/80) were multidrug resistant (MDR). The frequency of the bla_CTX-M gene was 65.0% and 77.5% of the isolates were biofilm producers. ESBL-producing UPEC isolates were clustered by the ERIC-PCR method into the nine groups labeled A-I. Conclusion: Our findings indicate a high and rising prevalence of MDR and ESBL-producing UPEC among children with VUR. This underscores the urgent need for appropriate empirical antibiotic selection, routine monitoring of resistance patterns, and long-term prophylactic strategies to reduce recurrence and improve clinical management in this vulnerable population.

This study analyzed the antimicrobial resistance profiles and risk factors for carbapenem-resistant Acinetobacter baumannii (CRAB) in a tertiary hospital and developed a predictive model for infection control. Among 64 Acinetobacter baumannii isolates collected in 2024 from the First People's Hospital of Chuzhou, CRAB accounted for 40.63% (26/64), with sputum being the most common specimen source (85.94%) and the highest isolation rate observed in respiratory wards. CRAB exhibited significantly higher resistance to most antibiotics compared to carbapenem-sensitive strains (CSAB), except for polymyxin and tigecycline (P < 0.05). Multivariate analysis identified ≥3 underlying diseases, prior use of compound antibiotics, and tracheal intubation/incision as independent risk factors for CRAB infection. A nomogram prediction model constructed with R software demonstrated high predictive accuracy (C-index: 0.985). The findings highlight a concerning prevalence and multidrug resistance of CRAB in this setting, underscoring the need to enhance monitoring, early risk factor identification, and targeted interventions to reduce transmission and optimize antimicrobial stewardship.

Background: Trimethoprim-sulfamethoxazole (SXT) is widely used for Pneumocystis pneumonia prophylaxis. However, prolonged use may induce antimicrobial resistance, potentially compromising empirical therapy for urinary tract infections (UTIs). Methods: We retrospectively analyzed 3,525 patients with positive urine cultures at Shizuoka General Hospital (2018-2023). Among them, 149 received SXT prophylaxis. Antimicrobial susceptibility and the relationship between prophylaxis duration and resistance were evaluated. Results: Escherichia coli and Klebsiella pneumoniae were the most common pathogens. In the SXT prophylaxis group, E. coli susceptibility to SXT was significantly reduced (21.2% vs. 87.4%). Susceptibility to other antibiotics also declined, including ampicillin (31.2% vs. 71.6%), piperacillin (32.5% vs. 74.8%), levofloxacin (57.5% vs. 74.7%), and ciprofloxacin (56.2% vs. 74.1%). Susceptibility to expanded-spectrum cephalosporins, including second-, third-, and fourth-generation agents remained preserved. Receiver operating characteristic analysis identified a prophylaxis duration >406 days as predictive of SXT resistance (area under the curve 0.82, sensitivity 94%, and specificity 60%). Short-term prophylaxis (≤30 days) mitigated resistance, although E. coli susceptibility to SXT was still limited (47.8%). Conclusions: Prophylactic SXT use markedly reduces susceptibility to multiple antibiotics, especially penicillins and fluoroquinolones. Resistance correlates with prophylaxis duration. For empirical UTI therapy, intravenous expanded-spectrum cephalosporins may be preferable.

Staphylococcus haemolyticus is frequently associated with infections in hospitalized patients and acts as a reservoir for antibiotic resistance genes. The widespread use of vancomycin in treating serious infections has led to the emergence of heteroresistance to vancomycin in certain S. haemolyticus isolates. This study aimed to determine the rate of heteroresistant vancomycin-intermediate S. haemolyticus (hVISH) among 166 blood isolates collected from patients admitted to Jawaharlal Institute of Postgraduate Medical Education and Research between January 2017 and June 2018. E-test was done to determine vancomycin minimum inhibitory concentration (MIC). Heteroresistance screening was performed using brain heart infusion agar containing 4 µg/mL vancomycin (BHIV₄). Confirmation of heteroresistance was performed by population analysis-profile area under curve (PAP-AUC) analysis. Whole-genome sequencing was performed on eight isolates. All isolates were vancomycin-susceptible by E-test, while 18.7% exhibited heteroresistance by PAP-AUC. The sensitivity, specificity, positive predictive value, negative predictive value, and kappa agreement of BHIV₄ with PAP-AUC were 64.5%, 97.8%, 87%, 92.3%, and 0.692, respectively. Mutational analysis of the eight isolates revealed variations in vraSR, tcaRAB, walKR, yycHIJ, rpoBC, lytSR, clpP, phoR, PBP₄, msrR, cmk, and mprF operons, along with novel mutations in cell wall synthesis operons. The rate of hVISH isolation in our study is in agreement with other studies worldwide. As the sensitivity of BHIV₄ is only moderate, it may be prudent to consider alternate antibiotics if MIC of vancomycin approaches the breakpoint. Furthermore, our analysis revealed multiple mutations within glycopeptide resistance operons, providing a better understanding of the molecular mechanisms underlying heteroresistance in S. haemolyticus and its implications for antimicrobial therapy and surveillance strategies.

Background: Pseudomonas aeruginosa is an opportunistic pathogen that exhibits a strong resistance ability to antibiotics. Methods: The complete genome of P. aeruginosa CYZ was sequenced using a PacBio RS II system. The functions of all the predicted genes and proteins were classified and annotated using the Clusters of Orthologous Groups of proteins, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes databases. Furthermore, the antimicrobial resistance genes were also analyzed via the Comprehensive Antibiotic Resistance Database, and several types of antibiotics were selected to test the antimicrobial susceptibility. Phylogenetic relationships were investigated using the single nucleotide polymorphisms (SNPs) from 228 clinically isolated P. aeruginosa strains. Results: The genome size of P. aeruginosa CYZ is 6,382,603 bp and contains 5,807 protein-coding genes, with an average G + C content of 66.44%. Functional genomic analysis via the annotations of the databases identified a total of 499 antimicrobial resistance genes. P. aeruginosa CYZ showed resistance to 14 types of antibiotics. The phylogenetic analysis revealed that P. aeruginosa CYZ was closely related to P. aeruginosa PAO1. The P. aeruginosa strains exhibited no geographical specificity, and the variation in core genome SNPs was nonrandomly distributed. Conclusion: Our findings give valuable insight into the genetic antimicrobial-resistant features of P. aeruginosa as well as provide a genetic basis for the further study of the phenotype.

The primary purpose of this study was to assess the prevalence and the antimicrobial susceptibility rates of carbapenemase-producing Enterobacterales (CPE) in a German University Hospital during a 5-year period. From January 2020 to December 2024, all Enterobacterales detected were molecularly investigated for carbapenemases in every case of elevated minimum inhibitory concentration of ertapenem, meropenem, or imipenem. Subsequently, CPE were tested for susceptibility to reserve antibiotics. Overall, 101 CPE were identified. Most of the CPE strains harbored only one carbapenemase gene, such as bla_OXA-48 (n = 32, 31.6%), bla_NDM (n = 27, 26.7%), and bla_VIM (n = 14, 13.8%). The annual number of CPE detected increased during the observation period (2020, n = 5; 2021, n = 5; 2022, n = 24; 2023, n = 29; 2024, n = 38). We also observed a progressive rise of the proportion of CPE harboring a metallo-β-lactamase gene such as bla_NDM or bla_VIM (2020, 0.0%; 2021, 0.0%; 2022, 50.0%; 2023, 55.2%; 2024, 65.8%). Regarding the antimicrobial susceptibility, only 3.3% of all CPE isolates tested showed resistance to aztreonam/avibactam. In contrast, the resistance rates for cefiderocol and ceftazidime/avibactam amounted respectively to 12.8% and 53.9%. The increasing annual number of CPE at our hospital is associated with a rise of the proportion of metallo-β-lactamase-producing strains. The newly available antibiotic aztreonam/avibactam showed promising in vitro activity against CPE.

Escherichia coli is a genetically versatile organism capable of thriving in diverse environments, acting as a commensal in the intestine or as a pathogen in the urinary tract. E. coli causing urinary tract infections has acquired genes that enable it to colonize the urinary tract, survive immune response, and resist antimicrobials. In this study, we investigated the association between the ESBL (Extended Spectrum Beta Lactamase) phenotype and other antimicrobial resistances in E. coli associated with urinary tract infections (UTI-E. coli; n = 1,139) and compared them with commensal E. coli strains (n = 405) isolated from human fecal samples in the same communities and during the same period. Among UTI-E. coli strains, 16.9% were ESBL producers compared to 7.6% in commensal strains, and resistance to other antimicrobials was also significantly higher in UTI-E. coli. These results suggest that many UTI-E. coli and commensal E. coli lineages have been subjected to distinct antimicrobial pressures over time.

Introduction: Fluoroquinolone resistance in Escherichia coli, particularly uropathogenic E. coli (UPEC), is a growing concern worldwide. This study investigates the association between mutations in the gyrA and parC genes and fluoroquinolone resistance in UPEC isolates from Urine samples in Iran. Materials and Methods: In total, 150 UPEC isolates were collected, and then, 12 ciprofloxacin-resistant isolates were selected for molecular analysis. Antimicrobial susceptibility testing was performed using the disk diffusion method, and minimum inhibitory concentrations (MICs) of ciprofloxacin were determined by microbroth dilution. Polymerase chain reaction and sequencing were used to detect mutations in the quinolone resistance-determining regions (QRDRs) of gyrA and parC. Results: All isolates had MIC >4 and were resistant to all four fluoroquinolones and quinolones tested, including ciprofloxacin, norfloxacin, ofloxacin, and nalidixic acid. All isolates harbored mutations in both genes. The most frequent mutations in gyrA were Ser-83→Leu and Asp-87→Asn, found in 100% of isolates. Similarly, mutations in parC, including Ser-80→Ile (83.3%) and Glu-84→Val (58.3%), were prevalent. Additional nucleotide substitutions in both genes were observed. These mutations likely contribute to the high-level fluoroquinolone resistance observed in the isolates. Conclusions: The results of this study confirm that mutations in the gyrA and parC genes primarily drive fluoroquinolone resistance in UPEC isolates. The presence of specific alterations within the QRDRs significantly reduces bacterial susceptibility to fluoroquinolones, contributing to the persistence and spread of resistant strains. Identifying these mutations provides critical insights into resistance mechanisms, which can aid in developing more effective antimicrobial therapy strategies.