First detection of CTX-M-1, CMY-2, and QnrB19 resistance mechanisms in fecal Escherichia coli isolates from healthy pets in Tunisia.

Abstract Our objective was to analyze the carriage rate of extended-spectrum β-lactamase (ESBL)- and plasmidic AmpC β-lactamase (pAmpC)-producing Escherichia coli isolates in fecal samples of healthy pets (dogs and cats) and to characterize the recovered isolates for the presence of other resistance genes and integrons. Eighty fecal samples of healthy pets were inoculated in MacConkey agar plates supplemented with cefotaxime (2 μg/mL) for cefotaxime-resistant (CTXR) E. coli recovery. CTXR E. coli isolates were detected in 14 of the 80 fecal samples (17.5%) and the following β-lactamase genes (number of isolates) were detected: blaCTX-M-1 (8), blaCTX-M-1+blaTEM-1b (3), blaCTX-M-1+blaTEM-1c (1), blaCTX-M-1+blaTEM-135 (1), and blaCMY-2+blaTEM-1b (1). The 14 E. coli were distributed into the phylogroups B1 (6 isolates), A (5), and D (3). The qnrB19 gene was detected in one CTX-M-1-producing strain of phylogroup D. Five isolates contained class 1 integrons with the following arrangements: dfrA17-aadA5 (2 isola...