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

This study aimed to describe the distribution and characterization of fecal extended-spectrum β-lactamase (ESBL)- and AmpC-producing 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 isolates from healthy companion animals and cohabiting humans were ESBL/AmpC producers, respectively. The gene was the most prevalent ESC resistance gene in both pets ( = 25/95, 26.3%) and humans ( = 44/126, 34.9%). The gene was also largely detected in pets ( = 19, 20.0%). Overall, intrahousehold pet-human sharing of ESBL/AmpC isolates occurred in 4.8% of households, and the isolates were all CTX-M-14 producers. In particular, ten CMY-2-producing 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 isolates were proportional to the copy number on the chromosome. Our results showed that the clonal spread of fecal ESBL/AmpC-producing households' isolates between healthy companion animals and cohabiting humans was rare, but it could happen. In particular, ST405 isolates carrying multiple genes on the chromosome was sporadically spread between companion animals and humans in South Korea.