Contamination of campylobacter isolates from broilers during slaughtering process

Abstract

The objective of the present study was to determine contamination rates, concentration and genotypes of Campylobacter on broiler carcasses during slaughtering processes. A total of 320 samples including cloacal swabs (n=40), carcass rinses during slaughtering process (n=200) and ceca (n=80) from 8 Campylobacter positive broiler farms were collected from 3 slaughterhouses during June 2012 to April 2013. Carcass rinses were taken after scalding, defeathering, evisceration, inside-outside (I/O) washing and chilling steps. To determine Campylobacter contamination rates, direct plating method and selective enrichment method were performed, while the concentration of Campylobacter on chicken carcasses was detected by direct plating method. In addition, genotyping of Campylobacter isolates was carried out by flaA-short variable region (flaA-SVR) sequencing. The occurrence of Campylobacter in carcass rinse, cecum and cloacal swab was 74.5%, 73.6% and 62.5%, respectively. Our finding revealed high Campylobacter contamination rates after defeathering (85%) and evisceration (82.5%) which was higher than after scalding (50%). The contamination rate remained high after I/O washing (80%) and chilling (75%). The mean concentration of Campylobacter on carcasses after scalding was 1.88 log CFU/ml. Campylobacter concentration significantly increased (p<0.05) after defeathering (2.76 log CFU/ml) and evisceration (3.26 log CFU/ml). Mean concentration was highest after I/O washing (3.42 log CFU/ml) and significantly declined to 2.04 log CFU/ml after chilling (p<0.05). Reduction in the concentration of Campylobacter on post-chill carcasses was found in all slaughterhouses; with or without the use of chlorine during chilling step. FlaA-SVR types obtained during slaughtering process were different among broiler flocks. The most common allele types identified among Campylobacter isolates in this study were flaA-SVR allele 208, 287, 769 and 783. FlaA-SVR types recovered from carcass rinse during slaughter were mostly related to allele types present in cecum and cloacal swab. Since defeathering was considered as a crucial step, aside from evisceration, for Campylobacter contamination on chicken carcasses during slaughter, the implementation of measures to reduce Campylobacter contamination during defeathering is necessary for controlling Campylobacter contamination at the slaughter level. Additionally, if chickens enter slaughterhouse with high loads of Campylobacter, it will be almost impossible to get rid of this foodborne pathogen from fully processed carcasses. Therefore, intervention strategies to prevent the introduction of Campylobacter into broiler farms are required and should be urgently investigated.