Prevalence and antimicrobial resistance of Salmonella and ESBL E. coli isolated from dairy cattle in Henan Province, China

Abstract

Salmonella and ESBL-producing E. coli pose a threat to public health through the food chain. A cross-sectional study was conducted to determine the prevalence and antimicrobial resistance of Salmonella and ESBL E. coli in apparently healthy lactating dairy cattle in Henan Province. Thirty-five lactating cows per farm were sampled by fecal swabbing from 38 farms, with samples being pooled to a total of 7 pooled samples per herd. Eight of the 266 pooled fecal samples (3.0%) were positive for Salmonella (95% confidence intervals (CI): 1.3, 5.8) with a herd-level Salmonella prevalence of 13.2% (95% CI: 4.4, 28.1). The within-herd prevalence for pooled samples for Salmonella ranged from 0.0% to 28.6%. A high proportion of resistance to tetracycline (6/8) and florfenicol (6/8) was obtained in the cultured Salmonella. Multi-drug resistant isolates were observed on 4/5 Salmonella-positive farms. ESBL E. coli were identified on all farms (100% - 34/34, 95% CI: 89.7, 100). All ESBL E. coli isolates (n = 216) contained the bla_CTX-M gene and two isolates also contained the bla_TEM gene. Our study reports the prevalence and antimicrobial resistance of Salmonella and ESBL E. coli in apparently healthy lactating dairy cows from Henan Province.

Keywords: Antimicrobial resistance; Dairy cattle; E. coli; ESBL; Henan; Salmonella.