Antimicrobial Resistance Gene of Salmonella enterica Isolated from Lab Equine Fecal Samples and Human Diarrheal Samples

Abstract

Antimicrobial resistance (AMR) of S. enterica is a global public health threat. The prevalence, antimicrobial susceptibility, and integron-mediated resistance of Salmonella enterica isolated from human diarrheal and laboratory equine fecal samples were investigated. Selective enrichment, culture on Salmonella–Shigella agar, and biochemical confirmation were used to process a total of 172 samples (104 human and 68 equine). Susceptibility to eight antibiotics was determined by Kirby–Bauer disc diffusion. Integrons were PCR amplified and typed using Hinf1 restriction enzyme. Salmonella enterica was isolated from 47 samples (27.32%): 37/104 (35.57%) human and 10/68 (14.70%) equine. All isolates were resistant to ampicillin (100%) and cefotaxime (100%) and were also resistant to sulphamethoxazole–trimethoprim (66.6%) and chloramphenicol (66.6%), but were susceptible to ceftazidime, nalidixic acid, and gentamicin. All isolates were subjected to amplification of integron genes (492 bp). Class I integrons were observed at greater frequency (90%), class II (10%), and class III was not observed at all. High-level resistance and carriage of class I integrons are both commonly associated with both host species, suggesting a common reservoir of resistance and a potential for horizontal transmission, making integrated One Health surveillance viable.