Molecular Characterization of Fecal Extended-Spectrum β-Lactamase- and AmpC β-Lactamase-Producing Escherichia coli From Healthy Companion Animals and Cohabiting Humans in South Korea

Abstract

This study aimed to describe the distribution and characterization of fecal extended-spectrum β-lactamase (ESBL)- and AmpC-producing <i>Escherichia coli</i> isolates from healthy companion animals and cohabiting humans. A total of 968 rectal swab samples from 340 participants, including healthy companion animals and cohabiting humans, were collected from 130 households in South Korea from 2018 to 2019. To determine the bacterial profiles of the participants, several experiments were performed as follows: antimicrobial susceptibility testing, PCR and direct sequencing for ESBL/AmpC production, PFGE, MLST, whole genome sequencing and qRT-PCR. A total of 24.9 and 21.5% of the <i>E. coli</i> isolates from healthy companion animals and cohabiting humans were ESBL/AmpC producers, respectively. The <i>bla</i> _CTX-M- ₁₄ gene was the most prevalent ESC resistance gene in both pets (<i>n</i> = 25/95, 26.3%) and humans (<i>n</i> = 44/126, 34.9%). The <i>bla</i> _CMY- ₂ gene was also largely detected in pets (<i>n</i> = 19, 20.0%). Overall, intrahousehold pet-human sharing of ESBL/AmpC <i>E. coli</i> isolates occurred in 4.8% of households, and the isolates were all CTX-M-14 producers. In particular, ten CMY-2-producing <i>E. coli</i> isolates from seven dogs and three humans in the different households belonged to the same pulsotype. The MIC values of cefoxitin and the transcription level in CMY-2-producing <i>E. coli</i> isolates were proportional to the <i>bla</i> _CMY- ₂ copy number on the chromosome. Our results showed that the clonal spread of fecal ESBL/AmpC-producing <i>E. coli</i> households' isolates between healthy companion animals and cohabiting humans was rare, but it could happen. In particular, <i>E. coli</i> ST405 isolates carrying multiple <i>bla</i> _CMY- ₂ genes on the chromosome was sporadically spread between companion animals and humans in South Korea.