Prevalence, multidrug-resistance and risk factors for AmpC β-lactamases producing Escherichia coli from hospitalized patients

Abstract

Introduction: Multi-drug resistance among AmpC β-lactamases producing Escherichia coli isolates is alarming. The study aimed to know the prevalence and presumptive antibiogram of AmpC producing Escherichia coli isolates and to determine the associated risk factors.

Methodology: Escherichia coli isolated from various clinical specimens from hospitalized patients during the study period (January 2018- December 2018) were taken for the study. Standard biochemical reactions were used for organism identification. Antibiotic susceptibility testing was done using Kirby-Bauer method as per CLSI guidelines. Cefoxitin resistance was taken as screening tool to detect AmpC producing strains. The phenotypic confirmation was done using modified three-dimensional test. Multiplex PCR was used to detect pAmpC.

Results: A total non-duplicate consecutive 470 Escherichia coli were isolated from various clinical specimens of hospitalized patients during the study period. Cefoxitin resistance was observed in 51.9% (244/470). Modified three dimensional test was positive in 115/244 (47.1%) strains. Genotypic characterization of phenotypic positive AmpC strains showed presence of CIT and DHA genes among 33/115 and 19/115 isolates respectively. The overall prevalence of pAmpC producing E. coli was found to be 52/470 (11.1%). Multidrug resistance (MDR) was observed in 42/52 (80.7%) pAmpC strains. Antimicrobial use, prolonged hospitalization and interventions were associated risk factors for AmpC producing isolates.

Conclusions: A high prevalence of multidrug resistance among AmpC producing strains suggests plasmid mediated spread of drug resistance in E. coli. Every hospital should formulate and implement infection control policies at-least for the risk group patients to control the dissemination of such microbes as infection prevention is better than infection control.