Prevalence of Campylobacter and Salmonella at a squab (young pigeon) processing plant

Abstract

Microbiological testing for Campylobacter and Salmonella was performed at a processing plant for squab (young pigeon) in three separate trials. Live birds, carcasses, and equipment were targeted for sampling during the preslaughter, pre-evisceration, and postevisceration stages of processing. The three trials represented 18 farms (1,110 squab), 1 farm (250 squab), and 23 farms (2,900 squab). The overall prevalence of positive samples in Trial 1 was 1.4% for Salmonella spp. and 11.1% for C. jejuni; in Trial 2, 4.3 and 0% for Salmonella spp. and C. jejuni; and in Trial 3, 4.1 and 4.8% for Salmonella spp. and C. jejuni, respectively. These observations represent a significantly greater likelihood of having a positive sample for Campylobacter (twofold) or Salmonella (eightfold) at processing, compared with prevalences observed in our previous on-farm study. This finding suggests an overall increase in the number of carcasses contaminated or in the concentration of contamination during transport and processing. In the multifarm trials, only Trial 3 demonstrated a significant increase in the prevalence of positive samples from the preslaughter to the postevisceration stages of processing (P = 0.02), and only for Campylobacter. The prevalence of positive cultures from equipment surfaces were not different than carcasses during processing, therefore no additional critical control points were identified within this system. When pooled swabs were compared (Trial 1) to individual swabs (Trials 2 and 3), no statistical difference in the prevalence of Salmonella or Campylobacter was observed between trials. Direct plating from a pooled sample onto selective agar media (Trial 1) and single swab culture with enrichment followed by plating on selective agar (Trials 2 and 3) were compared for Campylobacter isolation. No statistical difference in C. jejuni prevalence was observed using either method; however, when the detection limit of each method was determined, single swabs with enrichment had greater sensitivity.