Prevalence and antimicrobial resistance of Salmonella isolated from backyard pigs in Chiang Mai, Thailand

Abstract

Salmonella is a major zoonotic pathogen causing public health problems worldwide. There is limited information about the prevalence of Salmonella in backyard pigs. This study aimed to determine the prevalence and antimicrobial resistance of Salmonella in backyard pigs. A total of 93 fecal samples were randomly collected from backyard pigs in Chiang Mai, Thailand during November 2016 – March 2017 for Salmonella isolation and antimicrobial susceptibility testing. The prevalence of Salmonella in backyard pigs was 21.51%. Nine Salmonella serovars were observed. Salmonella I 4,5,12:i:- (31.03%) was the most prevalent serovar followed by, Salmonella Weltevreden (17.24%), Salmonella Rissen (13.8%), Salmonella Bovismorbificans (10.34%) and Salmonella Stanley (10.34%). The Salmonella isolates were most resistant to streptomycin followed by tetracycline, ampicillin, and sulfamethoxazole/trimethoprim. However, none of isolates were resistant to cefoxitin, nalidixic, and imipenem. Sixteen different patterns of multi-resistant isolates were observed. The most frequently multi-resistance pattern was AMP-TET-SXT-S. In summary, backyard pigs could play a role as reservoirs harboring Salmonella which can be transmitted to human and other backyard animals. Their wide range of resistance to different classes of antimicrobial agents should be concerned as it could transmit and pose a public health risk to human.