Detection of acrA, acrB, aac(6′)-Ib-cr, and qepA genes among clinical isolates of Escherichia coli and Klebsiella pneumoniae

Background: The distribution of drug resistance among clinical isolates of Escherichia coli and Klebsiella pneumoniae has limited the therapeutic options. The aim of this study was to report the prevalence of quinolone resistance genes among E. coli and K. pneumoniae clinical strains isolated from three educational hospitals of Tehran, Iran. Materials and methods: A total of 100 strains of E. coli from Labbafinejad and Taleghani Hospitals and 100 strains of K. pneumoniae from Mofid Children and Taleghani Hospitals were collected between January 2013 and May 2014. Antimicrobial susceptibility tests were done by disk diffusion method based on Clinical and Laboratory Standards Institute guidelines. Detection of qepA, aac(6′)-Ib-cr, acrA, and acrB genes was done by polymerase chain reaction (PCR). Results: In this study, fosfomycin and imipenem against E. coli and fosfomycin and tigecycline against K. pneumoniae had the best effect in antimicrobial susceptibility tests. PCR assay using specific primers demonstrated that the prevalence of qepA, aac(6′)-Ib-cr, acrA, and acrB genes among the 100 E. coli isolates was 0 (0%), 87 (87%), 92 (92%), and 84 (84%), respectively. The prevalence of qepA, aac(6′)-Ib-cr, acrA, and acrB genes among the 100 K. pneumoniae isolates was 4 (4%), 85 (85%), 94 (94%), and 87 (87%), respectively. Conclusion: The distribution of qepA, aac(6′)-Ib-cr, acrA, and acrB resistance determinants in E. coli and K. pneumoniae is a great concern. Therefore, infection control and prevention of spread of drug-resistant bacteria need careful management of medication and identification of resistant isolates

Emergence of fosfomycin resistance among isolates of Escherichia coli harboring extended-spectrum and AmpC β-lactamases

Urinary tract infection (UTI) is a common type of infectious disease globally. The aim of this study was to detect the frequency of fosA3 and fosC2 genes in extended-spectrum β-lactamases (ESBL) and blaDHA, blaCMY-2, and blaCMY-42 genes in AmpC β-lactamases-producing isolates of Escherichia coli. In total, 120 isolates of E. coli were collected from three teaching hospitals between March 2014 and February 2015. Antibiotic susceptibility tests were carried out by disk diffusion method. The presence of blaCMY-2, blaCMY-42, blaDHA, fosA3, and fosC2 genes was detected by polymerase chain reaction (PCR) and sequencing. Of the 120 strains, 92 (76.6%) were identified as ESBL producers, 30 (25%) were determined as AmpC β-lactamase producers, and 24 (20%) had both ESBL and AmpC β-lactamase enzymes. Imipenem, fosfomycin, and nitrofurantoin had the best effect against isolates of E. coli. PCR assay demonstrated that the frequency of blaCMY-2, blaCMY-42, and blaDHA genes among AmpC β-lactamases-producing strains were 39%, 1%, and 17.5%, respectively. This study reports the first detection of fosfomycin resistance in Iran. This study indicated the increasing prevalence of UTI isolates of E. coli-harboring ESBL and AmpC β-lactamases genes in Iran. Therefore, due to the high rate of blaDHA and blaCMY genes and emergence of fosfomycin-resistant E. coli isolates, we recommend continuous monitoring of antibiotic resistance as well as attention to guidelines of infection controls

Antibiotic Resistance and RAPD-PCR Genotyping of Pseudomonas aeruginosa Clinical Strains Isolated from Intensive Care Unit Patients

Background: Pseudomonas aeruginosa is one the most important nosocomial pathogens, especially in immunocompromised patients. Identifying the source of contamination in health centers plays an important role in the control of hospital infections. The aim of this study was to determine antibiotic susceptibility and genetic patterns of P. aeruginosa isolated from patients hospitalized in intensive care unit of Masih Daneshvari Hospital, Tehran, Iran. Materials and Methods: Antibiotic susceptibility of the isolates was examined through 10 antibiotics recommended by Clinical and Laboratory Standards Institute (CLSI, 2018) guidelines using the Kirby-Bauer disc diffusion method. Random amplified polymorphic DNA (RAPD) analysis with the short primer of 272 was used to evaluate genetic relationship among the isolates and the results were analyzed by Gelcompar II software. Results: Of the antibiotics used, the most sensitive was found in colistin (96.4%) and the highest resistance rates were observed in cefotaxime (94.6%), chloramphenicol (83.9%) and imipenem (71.4%). DNA fingerprinting was able to identify 12 genetic patterns by RAPD-PCR technique. Conclusion: Antibiotic resistance in isolates of P. aeruginosa is rising and there is possibility of occurring outbreaks in the medical centers. Different sources of strains show their constant exchange via intra- and extra-hospital transmission routes. Thus, according to the data of this study, there is a serious need to control sources of infections by physicians and staff when they are working in several sectors to control and prevent the transmission of the bacterium

To Study the Association between AcrAB and Qep A Efflux Pumps and Ciprofloxacin Resistance among Escherichia Coli and Klebsiella Pneumoniae Clinical Strains

Abstract Background: The efflux pumps are one of the main mechanisms of resistance to antibiotics in E. coli and K. pneumoniae strains. The aim of this study is to study the association between genes coding efflux pumps AcrAB and Qep A and ciprofloxacin resistance among E. coli and K. pneumoniae clinical strains Materials and Methods: This study was done on 100 strains of E. coli isolated from Taleghani and Labbafinejad Hospitals and 100 strains of K. pneumoniae isolated from Taleghani and Mofid Children Hospitals. Antimicrobial susceptibility tests were performed by disk diffusion method based on CLSI guidelines. Identification of genes encoding efflux pumps Acr AB and Qep A was done by PCR technique. Results: In this study, fosfomycin and imipenem had the best effect against E. coli clinical isolates and fosfomycin and tigecycline had the best effect against K. pneumoniae clinical isolates. PCR assay demonstrated that the prevalence of AcrA, AcrB and QepA genes among E. coli isolates were 92%, 84% and 0%, respectively and among K. pneumoniae isolates were 94%, 87% and 4%, respectively. Conclusion: The prevalence of genes encoding efflux pumps in E. coli and K. pneumoniae clinical strains, which causes resistance to fluoroquinolones, is cause for concern. Therefore, controlling infection and preventing the spread of drug-resistant bacteria needs to manage medication carefully and identify resistant isolates

Characterization and frequency of antibiotic resistance related to membrane porin and efflux pump genes among Acinetobacter baumannii strains obtained from burn patients in Tehran, Iran

Objective: To explore the characterization and frequency of antibiotic resistance related to membrane porin and efflux pump genes among Acinetobacter baumannii (A. baumannii) strains obtained from burn patients in Tehran, Iran. Methods: In this cross-sectional descriptive study, 100 strains of A. baumannii isolated from burn patients visiting teaching hospitals of Tehran were collected from January 2016 to November 2017. After A. baumannii strains were confirmed, antimicrobial susceptibility testing was done via Kirby-Bauer disc diffusion method according to the Clinical and Laboratory Standards Institute guidelines. PCR amplification was performed for detection of β -lactamase adeR, OprD, adeS genes among A. baumannii strains. Results: All isolates (100%) were resistant to ceftazidime, cefotaxime, cefepime, ciprofloxacin, and piperacillin, and most isolates indicated high resistance (95%-97%) to meropenem, imipenem, gentamicin, ceftriaxone, trimethoprim-sulfamethoxazole, piperacillin-tazobactam, amikacin, and tetracycline. The most effective antibiotic against A. baumannii isolates was colistin (97% sensitivity), followed by tigecycline. The frequency of OprD, adeS, and adeR genes were 98%, 91%, and 77%, respectively. Conclusions: This study shows that the majority of A. baumannii isolates are highly resistant to the antibiotics most commonly used in burn patients. Also, high distribution of OprD and adeRS genes may be responsible for the observed resistances among A. baumannii isolates that demonstrate the possible role of both efflux pumps in simultaneous of carbapenemase production during antibiotic resistance