Prevalence and molecular characterization ofSalmonella entericaisolates throughout an integrated broiler supply chain in China
SUMMARYA total of 1145 samples were collected from chicken breeder farms, hatcheries, broiler farms, a slaughterhouse and retail refrigerated chicken stores in an integrated broiler supply chain in Guangdong Province, China, in 2013. One-hundred and twoSalmonella entericastrains were isolated and subjected to serotyping, antimicrobial susceptibility testing, virulence profile determination and molecular subtyping by pulsed field gel electrophoresis (PFGE). The contamination rates in samples from breeder farms, hatcheries, broiler farms, the slaughterhouse and retail stores were 1·46%, 4·31%, 7·00%, 62·86% and 54·67%, respectively. The isolated strains ofS. entericabelonged to 10 serotypes; most of them wereS. Weltevreden (46·08%, 47/102) andS. Agona (18·63%, 19/102). Isolates were frequently resistant to streptomycin (38·2%), tetracycline (36·3%), sulfisoxazole (35·3%) and gentamicin (34·3%); 31·4% of isolates were multidrug resistant. The isolates were screened for 10 virulence factors. TheSalmonellapathogenicity island genesavrA, ssaQ, mgtC, siiD, andsopBand the fimbrial genebcfCwere present in 100% of the strains. PFGE genotyping of the 102S. entericaisolates yielded 24 PFGE types at an 85% similarity threshold. The PFGE patterns show that the genotypes ofS. entericain the production chain are very diverse, but some strains have 100% similarity in different parts of the production chain, which indicates that someS. entericapersist throughout the broiler supply chain.