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Background <p>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 <i>Escherichia coli</i> (UPEC).</p> Methods <p>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 <i>bla</i><sub>ACC</sub>, <i>bla</i><sub>CMY</sub>, <i>bla</i><sub>DHA</sub>, <i>bla</i><sub>FOX</sub>, <i>bla</i><sub>IMP−1</sub>, <i>bla</i><sub>IMP−2</sub>, <i>bla</i><sub>VIM−1</sub>, and <i>bla</i><sub>VIM−2</sub> were detected by polymerase chain reaction (PCR).</p> Results <p>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 <i>bla</i><sub>IMP−2</sub> (16.19%), <i>bla</i><sub>DHA</sub> (10.48%), and <i>bla</i><sub>VIM−1</sub> (5.71%), whereas <i>bla</i><sub>ACC</sub>, <i>bla</i><sub>CMY</sub> and <i>bla</i><sub>FOX</sub> were not detected. Most isolates (64.76%) lacked the investigated BLGs.</p> Conclusions <p>UPEC isolates from Tehran exhibited substantial antimicrobial resistance, including MDR, XDR, and PDR phenotypes. ESBL and AmpC producers were common, with <i>bla</i><sub>IMP−2</sub>, <i>bla</i><sub>DHA</sub>, and <i>bla</i><sub>VIM−1</sub> predominating. Universal ampicillin/amoxicillin resistance and marked phenotypic-genotypic diversity suggest additional resistance mechanisms.</p>

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

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月2日

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  • Maryam Shirzadian,
  • Fatemeh Foroohi,
  • Abbas Fallah Vosoughi,
  • Shervindokht Ahmadi,
  • Taha Golpasand,
  • Payam Behzadi

摘要

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.