Molecular detection of plasmid-derived AmpC β-lactamase among clinical strains of Enterobacteriaceae in Bahrain.

Background: Enterobacteriaceae with AmpC β-lactamase are multidrug-resistant organisms and represent a significant challenge to patient care. This study aims to determine the prevalence of plasmid-derived AmpC β-lactamase among extended spectrum β-lactamases (ESBL)-producing Enterobacteriaceae strains in Bahrain.

Methods: It was a cross-sectional study. A total of 185 ESBL-producing Enterobacteriaceae isolates were recovered from clinically significant specimens from January 2018 to December 2019. The samples underwent initial screen for cefoxitin resistance by disc diffusion test and subsequent phenotypic confirmation of AmpC production with phenyl boronic acid assays as well as genotypic analysis by multiplex polymerase chain reactions for AmpC subtypes. Drug-resistant features of these clinical isolates were also examined.

Results: Twenty-nine ESBL-producing Enterobacteriaceae isolates were cefoxitin resistant. Phenotypic and genotypic analyses confirmed that 8 and 12 cefoxitin-resistant isolates are AmpC positive, respectively. These AmpC producers are multidrug resistant, and Escherichia coli is the dominant strain among them.

Conclusions: Plasmid-mediated spread of AmpC is present in clinically relevant Enterobacteriaceae species in Bahrain. Rational antimicrobial therapy against these multidrug-resistant organisms and continued surveillance of antimicrobial resistance mechanisms among the clinical isolates are recommended for optimal patient care.