Insights into antimicrobial resistance: dissemination and molecular epidemiology of carbapenemase and AmpC genes in uropathogenic Escherichia coli.

BACKGROUND

This study investigated the prevalence of acquired/natural AmpC β-lactamase genes (ABLGs) and acquired carbapenemase genes (ACGs) and their association with antimicrobial resistance in uropathogenic Escherichia coli (UPEC).

METHODS

A total of 105 non-duplicate UPEC isolates recovered from urine specimens collected in Tehran, Iran (August 2023-January 2024), were analyzed. Antimicrobial susceptibility testing was performed by the Kirby-Bauer method. ESBL and AmpC phenotypes were determined phenotypically, and blaACC, blaCMY, blaDHA, blaFOX, blaIMP-1, blaIMP-2, blaVIM-1, and blaVIM-2 were detected by polymerase chain reaction (PCR).

RESULTS

Resistance to ampicillin and amoxicillin was observed in all isolates, followed by ciprofloxacin (75.24%), ofloxacin (60.95%), and cefotaxime (60.95%). ESBL and AmpC phenotypes were detected in 37.14% and 11.43% of isolates, respectively. MDR, XDR, and PDR phenotypes occurred in 55.24%, 16.19%, and 2.86% of isolates. The most prevalent β-lactamase genes (BLGs) were blaIMP-2 (16.19%), blaDHA (10.48%), and blaVIM-1 (5.71%), whereas blaACC, blaCMY and blaFOX were not detected. Most isolates (64.76%) lacked the investigated BLGs.

CONCLUSIONS

UPEC isolates from Tehran exhibited substantial antimicrobial resistance, including MDR, XDR, and PDR phenotypes. ESBL and AmpC producers were common, with blaIMP-2, blaDHA, and blaVIM-1 predominating. Universal ampicillin/amoxicillin resistance and marked phenotypic-genotypic diversity suggest additional resistance mechanisms.