Molecular Characterization of ESBL and Carbapenemase-Producing Uropathogenic <i>Escherichia coli</i> in Hospitalized Patients, Tehran, Iran

Background: Uropathogenic Escherichia coli with antibiotic resistance and virulence factors can cause urinary tract infections (UTIs). Objectives: This study aimed to evaluate the genetic characteristics of extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing E. coli (CP-E. coli) isolates. Methods: This study was conducted in 2020 on 300 urine samples. The antibiotic susceptibility of the isolates was evaluated using the disk diffusion method. The minimum inhibitory concentrations (MICs) of meropenem (MEM), ceftazidime/avibactam (CAZ/AVI), and colistin were determined by E-test and microbroth dilution, respectively. Antibiotic resistance genes, virulence factors, phylogroups, and serogroups were detected using polymerase chain reaction (PCR). The relationship between the isolates was assessed using pulsed-field gel electrophoresis (PFGE) typing. Sequence type 131 (ST131) isolates were identified by PCR. Results: A total of 100 isolates were collected, of which 36% (n = 36) were ESBL-producing E. coli (EP-E. coli), and 33.5% (n = 11/36) were CP-E. coli. Among the 36 EP-E. coli isolates, 80.5% (n = 29) harbored the blaCTX-M gene, and 19.4% (n = 7) were identified as ST131. The most prevalent virulence gene was fimH (97.2%; n = 35). The O1 serogroup (36.1%; n = 13/36) was predominant. Phylogroup typing showed that 52.7% (n = 19/36) of isolates belonged to the B2 phylogroup, and PFGE typing detected 32 singletons and 2 clusters. Conclusions: Our findings revealed a high prevalence of antibiotic resistance in EP-E. coli isolates, likely due to the excessive clinical use of antibiotics. Additionally, CP-E. coli isolates belonging to ST131-O25-B2 carried blaNDM and blaOXA-48 genes. Given the limited treatment options, continuous surveillance is essential to control the spread of these multidrug-resistant (MDR) E. coli strains.