Prevalence and antimicrobial resistance of Salmonella spp. isolated from swine and poultry farms in Cambodia.

Abstract

Background and aim: The indiscriminate use of antimicrobials in livestock farming has contributed to the emergence of antimicrobial-resistant pathogens, posing a significant public health challenge. This study aimed to assess the prevalence and antimicrobial resistance (AMR) profiles of Salmonella spp. isolated from swine and poultry in small- and medium-scale farms in Cambodia.

Materials and methods: A total of 638 fecal samples (273 rectal swabs from swine and 365 cloacal swabs from poultry) were collected from five provinces in Cambodia from June to September 2021. Salmonella spp. isolation followed ISO 6579:2002 guidelines, and antimicrobial susceptibility testing was conducted using the disk diffusion method, adhering to Clinical and Laboratory Standards Institute 2020 standards. Resistance was assessed against nine antimicrobial agents across five major classes.

Results: Overall, Salmonella was detected in 6.58% (42/638) of samples, with 6.96% (19/273) from swine and 6.30% (23/365) from poultry. Swine-derived isolates exhibited the highest prevalence in the growing stage (13.93%), whereas poultry isolates were most common in avian broilers (14.55%). High resistance was observed against β-lactams (penicillin, amoxicillin, and ampicillin), tetracyclines, and sulfonamides, with resistance rates ranging from 73.81% to 100%. Fluoroquinolone resistance (ciprofloxacin and norfloxacin) was moderate (29.77%), while aminoglycoside resistance (gentamicin) was low (2.38%). Multidrug resistance (MDR) patterns were identified in 91.30% (21/23) of poultry isolates and 52.63% (10/19) of swine isolates, with resistance spanning three to five antimicrobial classes.

Conclusion: The presence of Salmonella in Cambodian swine and poultry farms and its high level of MDR underscore the urgent need for improved antimicrobial stewardship. The study highlights the risk of MDR Salmonella transmission through livestock production chains, emphasizing the necessity for stringent regulatory interventions, biosecurity measures, and surveillance programs to mitigate AMR spread in animal agriculture and public health sectors.