Determination of antibiotic susceptibility, ESBL genes and pulsed-field gel electrophoresis profiles of extended-spectrum β-lactamase-containing escherichia coli isolates

The purpose of this study was to determine the phenotypic antibiotic susceptibility patterns, extended-spectrum β-lactamase (ESBL) genes and genotypic profiles of ESBL-positive Escherichia coli strains isolated from urine samples obtained from outpatients with urinary tract infection in Turkey. A total of 120 E. coli strains during 2017, 2018, and 2019 (40 patients per year) were examined for antibiotic susceptibility patterns by disc diffusion method, for ESBL genes using PCR and sequencing and for molecular typing by pulsed-field gel electrophoresis (PFGE) method. The isolates were evaluated for their sensitivity to 21 different antibiotics. Four different antimicrobial resistance patterns were determined according to antibiotic susceptibility status of the isolates. The β-lactamase genes detected in the isolates were CTX-M-15 + OXA-1 (n= 14), CTX-M-15 (n= 24), TEM-1 + CTX-M-15 (n= 52), TEM-1 + SHV-12 (n=6), SHV-12 1 (n= 6), TEM-1 + CTX-M-1 (n= 6), TEM-1 + CTX-M-16 (n= 6) and TEM-1 + CTX-M-9 (n= 6). The CTX-M-15 was the most prevalent ESBL enzyme in the isolates. As a result of PFGE analysis performed by XbaI enzyme restriction process, one major PFGE profile and three main groups (Group I-II-III) were observed. While antibiotic resistance profiles of the strains showed four groups (RI-RII-RIII-RIV), PFGE band profiles showed a major group (90% similarity ratio). High ESBL production and decreased susceptibility to broad-spectrum cephalosporins were observed in E. coli strains. In addition, PFGE analysis showed high clonal similarity among E. coli isolates.