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Updated: May 8, 2026
Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
Molecular epidemiology, resistance profiles and clinical features in clinical plasmid-mediated AmpC-producing
M Jose Gude1, Cristina Seral, Yolanda Sáenz
1Servicio de Microbiología. Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain.
Abstract:
During the 30 months of surveillance period, 85 pAmpC-producing isolates were detected (prevalence 0.56% overall): blaCMY-2 gene in 70 E. coli, 2 K. pneumoniae and 6 P. mirabilis isolates; and the blaDHA-1 gene in 4 E. coli and 3 K. pneumoniae. In 8.23% of them, other β-lactamases (predominantly OXA-1) were identified. All pAmpC-producing isolates were susceptible to carbapenems, whereas high resistance to nalidixic acid, ciprofloxacin and trimethoprim-sulfamethoxazole was observed among pAmpC-producing isolates (80%, 60%, and 44.7%, respectively). In hospital patients, predisposing factors such as prior antibiotic use, previous hospitalization, presence of an indwelling device, invasive urinary tract procedures and mechanical ventilation were observed. In the community setting, urinary tract infection was the most common type of infection related to pAmpC-producing isolates. A wide heterogeneity of clones was found among our E. coli isolates by PFGE, suggesting that this mechanism of resistance is not due to the dissemination of a clonal strain. Surveillance of these resistance mechanisms in the community is thus needed. Awareness of pAmpC dynamic is required to prevent introduction into hospitals and to control the spread of this emerging resistance within the community.
Insights
The study found that plasmid-mediated AmpC (pAmpC)-producing bacteria, primarily E. coli, are emerging in the community. These resistant strains show high resistance to common antibiotics but remain susceptible to carbapenems, necessitating community surveillance.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Plasmid-mediated AmpC (pAmpC) beta-lactamases are a growing concern in bacterial pathogens.
- Understanding the prevalence and characteristics of pAmpC-producing isolates in both hospital and community settings is crucial.
Purpose of the Study:
- To determine the prevalence and characteristics of pAmpC-producing bacterial isolates.
- To identify risk factors and common infections associated with pAmpC producers.
- To investigate the genetic relatedness of pAmpC-producing E. coli.
Main Methods:
- Surveillance of bacterial isolates over 30 months.
- Identification of pAmpC genes (blaCMY-2, blaDHA-1) and other beta-lactamases (OXA-1).
- Antimicrobial susceptibility testing.
- Pulsed-field gel electrophoresis (PFGE) for E. coli clone analysis.
Main Results:
- 85 pAmpC-producing isolates detected (0.56% prevalence), mainly E. coli with blaCMY-2.
- High resistance to nalidixic acid (80%), ciprofloxacin (60%), and trimethoprim-sulfamethoxazole (44.7%).
- All isolates remained susceptible to carbapenems.
- Urinary tract infections were common in the community; hospital risk factors included prior antibiotic use and devices.
- PFGE revealed diverse E. coli clones, not a single dominant strain.
Conclusions:
- pAmpC-producing bacteria are present in the community with significant antibiotic resistance.
- Community surveillance is needed to prevent hospital introduction and control spread.
- Awareness of pAmpC dynamics is essential for managing this emerging resistance.
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