The risk of aerotolerant Campylobacter jejuni strains in poultry meat distribution and storage

Abstract

Poultry meat is a major vector for Campylobacter jejuni foodborne illness. Since C. jejuni is microaerophillic, the cell counts gradually decreased during distribution and display under aerobic condition. However, if the pathogen can resist to aerobic condition, it may cause serious problem in food safety. This study determined the aerotolerance of C. jejuni isolated from poultry and the risk of the aerotolerant C. jejuni strains. Fourteen C. jejuni strains isolated from poultry were subjected to aerobic condition in a shaking incubator at 500 rpm and 37 degrees C. The cell counts of C. jejuni strains were enumerated on modified CCDA-Preston at 0, 24, 72 and 120 h, and the strains, having reduction less than 2 Log CFU/mL for 120 h were determined as aerotolerant C. jejuni strain. Non-aerotolerant and aerotolerant C. jejuni strains were then incubated at 4 degrees C under aerobic condition to compare the growth between aerotolerant and non-aerotolerant strains. In addition, transcriptomes for virulence and stress response genes (cadF, cdtB, ciaB, clpP and htrB) were compared between non-aerotolerant and aerotolerant C. jejuni strains. Among 14 C. jejuni strains, seven strains (50%) showed less than 2-Log CFU/mL reduction at 37 degrees C after 24 h, and five strains of them still showed less than 2-Log CFU/mL reduction after 48 h. Especially, C. jejuni SMFM2015-Du7 and C. jejuni SMFM2014-Du16 were still survived after 120 h under aerobic condition, which were then determined as aerotolerant C. jejuni. However, at 4 degrees C under aerobic condition, there were no significant differences in the reduction of C. jejuni cell counts and virulence gene expressions between non-aerotolerant (C. jejuni SMFM2014-Du8) and aerotolerant strains (C. jejuni SMFM2015-Du7 and C. jejuni SMFM2014-Du16) except for stress response gene (htrB). These results indicate that there are aerotolerant C. jejuni strains, but their risk is similar to non-aerotolerant C. jejuni strains at 4 degrees C under aerobic condition, which is distribution and storage condition for poultry meat. Therefore, additional food safety management for the aerotolerant C. jejuni is not necessary.