Phenotypic and genotypic determination of aerotolerant growth in Campylobacter species isolated from commercial broiler chickens at slaughter

Campylobacter species are a leading cause of human foodborne illness which are often attributed to consumption of contaminated poultry meat products. Aerotolerant Campylobacter species are an emerging concern and therefore, we investigated phenotypic indicators of aerotolerance in 280 isolates of Campylobacter species isolated from broilers at processing over a seven-year period. Campylobacter were isolated from broiler chicken carcasses, ceca, and livers at slaughter over a seven-year span as part of a previous study. Greater than 48% of isolates investigated exhibited phenotypic characteristics of aerotolerance; defined here as the ability to grow under aerobic conditions. However, when exposed to peracetic acid, aerotolerant isolates did not exhibit different tolerance than non-aerotoloerant isolates. Additionally, we investigated potential genetic mechanisms to explain differences in aerotolerance. A single gene, encoding a hypothetical protein, was identified which was present in greater than 70% of isolates which grew under aerobic conditions and in less than 30% of isolates which never grew aerobically. Conversely, 24 genes were present in greater than 70% of non-aerotolerant isolates but absent from greater than 70% of aerotolerant isolates. This analysis identified genes which have the potential to influence aerotolerance in Campylobacter species, but further investigation is needed to confirm involvement.