Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of originating from pet animals in Chongqing, China.

A total of 334 isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Typhimurium monophasic variant, Kentucky, Enteritidis, Pomona, and Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of β-lactamase genes in isolates was 59.6%, and among these isolates, 185 harbored , followed by (66) and (10). Moreover, six PMQR genes, namely, including (4.8%), (4.2%), (0.9%), (18.9%), (16.5%), and (1.5%), were detected. QRDR mutations (76.6%) were very common in isolates, with the most frequent mutation in (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, (A) (39.5%), (B) (8.1%), (M) (7.7%), (D) (5.4%), (J) (3.3%), and (C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, (84.4%), (31.1%), and (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated has become a serious public health problem and has attracted increasing attention. There are no reports of from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of strains isolated from pet fecal samples in Chongqing. In addition, β-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.