Prevalence of Salmonella and E. coli, and their resistance to antimicrobial agents, in farming communities in northern Thailand.

A cross-sectional pilot study was conducted in Chiang Mai, Thailand, to determine the prevalence of Salmonella and Escherichia coli in swine, broiler chickens and human workers from farms and abattoirs in northern Thailand, and compare their antimicrobial resistance profiles. Fecal samples and cloacal swabs were collected from 150 swine and 150 chickens at the farm. Fecal samples from swine, cloacal swabs from chickens, and carcass swabs from both animals were collected from 100 swine and 100 chickens at the abattoir. Stool samples were collected from 15 swine farm workers and seven chicken farm workers. Primary isolation and identification of Salmonella and E. coli were conducted using standard methods. In vitro susceptibility testing of Salmonella and E. coli was conducted using the broth microdilution method, based on the United States National Committee for Clinical Laboratory Standards (NCCLS) guidelines. The prevalence of Salmonella from swine and chicken samples ranged from 2% to 25%. The prevalence of E. coli in chickens and swine ranged from 36.8% to 47.6%. In humans, the prevalence of Salmonella was 15%, and the prevalence of E. coli ranged from 51% to 53%. Resistance in Salmonella was found for tetracycline (84.7%), nalidixic acid (27.1%), florfenicol (18.6%), ampicillin (13.6%), and ceftiofur (3.4%), and in E. coli for tetracycline (91.5%), nalidixic acid (67.4%), ampicillin (61.6%), florfenicol (51.8%), enrofloxacin (28.7%), ciprofloxacin (12.5%), ceftiofur (4.9%) and ceftriaxone (1.5%).