Salmonella incidence and distribution of serotypes throughout processing in a Spanish poultry slaughterhouse

Abstract

A survey of contamination with Salmonella spp. was done at 11 sampling sites in a poultry slaughter establishment in Spain for a total of 192 samples. Samples included fecal material, utensils, water, and poultry carcasses and livers at several stages of processing. Salmonella incidence rates increased from 30% in fecal material collected from incoming birds to 60% in air-chilled carcasses and 80% in cold-stored livers, indicating that cross-contamination occurred. The rate of incidence of Salmonella organisms on carcasses averaged 56.7% through post-picking to post-air chilling and reached a maximum of 70% on carcasses at the post-spray wash site. Poultry livers were more heavily contaminated with salmonellae, as 55% and 80% samples after evisceration and cold storage, respectively, were positive for those pathogenic bacteria. From a total of 112 strains isolated, 87 (77.6%) were S. enteritidis, 7 (6.2%) Salmonella serotype 4,5,12:b:-(II), and 6 (5.4%) Salmonella serotype 4,12:b:-(II), and the remaining 12 strains were equally distributed among S. typhimurium, S. virchow, and S. blockley (3.6% each). Serotypes isolated from feces were later detected in matched carcasses and livers indicating a cross-contamination of carcasses by endogenous microflora in bird feces. The incidence of Salmonella serotype 4,5,12:b:-(II) and that of S. typhimurium were significantly higher (P < 0.05) in samples obtained prior to evisceration than in those collected after that particular step. The situation with S. enteritidis was quite the reverse, since this serotype was more frequently detected in samples taken after the evisceration step (P < 0.01).