Campylobacter jejuni and Campylobacter coli in broiler chicken livers: High prevalence and surface contamination, but low load in inner tissue.

Thermophilic Campylobacter spp. are the main cause of gastrointestinal illness in humans through contaminated food. Poultry and poultry products are the main sources of Campylobacter infection. Epidemiological data on Campylobacter prevalence and load in broiler livers remain limited and its presence in this offal may be associated with the caecal load. Hence, this study aimed to determine the prevalence and levels of Campylobacter in chicken livers, both from the surface and inner tissue, compared with that of caeca, by sampling 56 flocks from two slaughterhouses in Spain. Three carcasses per flock were randomly collected during evisceration (n = 168 livers and caecal contents). Overall Campylobacter prevalence was 57.1 % in caecal samples, 77.9 % in surface liver samples and 35.7 % in the inner tissue liver. C. jejuni was the most common species in all sample types and coinfections with C. coli were more prevalent in livers than in the caeca samples. However, there was no relationship between Campylobacter species (C. jejuni, C. coli) and sample type (P > 0.05). The data highlights the role of chicken offal as a potential source of human campylobacteriosis, particularly because of the high Campylobacter load (>10 CFU/liver) in a high proportion of the surface liver samples (40.1 %). However, this high load was only detected in 6.6 % of the inner tissue livers. Restriction fragment length polymorphism (RFLP) analysis revealed a high genetic diversity with 107 different profiles among 473 genotyped Campylobacter isolates. Translocation of Campylobacter strains was demonstrated, with the same RFLP profile identified in isolates from the caeca and the inner liver tissue of the same carcass (14.9 %). Cross-contamination was also revealed, since the same RFLP profile was identified in isolates from the caeca and the surface of the liver from the same carcass (11.9 %). Targeted measures on broiler farms and slaughterhouses to reduce Campylobacter prevalence and cross-contamination in chicken offal will help to reduce the risk of campylobacteriosis for consumers.