Campylobacter coli From Retail Liver and Meat Products Is More Aerotolerant Than Campylobacter jejuni

Abstract

Aerotolerance in the microaerophilic species Campylobacter was previously reported and could increase bacterial survival and transmission in foods during stressful processing and storage conditions. In this study, 167 Campylobacter isolates (76 C. jejuni and 91 C. coli) were screened for aerotolerance; these strains were previously isolated from retail chicken meat, chicken livers, chicken gizzards, turkey, pork, and beef liver samples. Bacterial cultures were incubated aerobically in Mueller Hinton broth with agitation and viable cell counts were taken at 0, 6, 12, and 24 h. Approximately 47% of the screened Campylobacter isolates were aerotolerant (viable after a 12-h aerobic incubation period), whereas 24% were hyper-aerotolerant (viable after a 24-h aerobic incubation). A greater prevalence of aerotolerant strains (80%) was found among C. coli isolates as compared to C. jejuni isolates (6%). Differences in the oxidative stress response related genes were detected among C. jejuni and C. coli isolates when comparative genomics was used to analyze 17 Whole Genome Sequenced (WGS) strains from our laboratory. Genes encoding putative transcriptional regulator proteins and a catalase-like heme binding protein were found in C. coli genomes, but were absent in the genomes of C. jejuni. PCR screening showed the presence of a catalase-like protein gene in 75% (68/91) of C. coli strains, which was absent in all tested C. jejuni strains. While about 79% (30/38) of the hyper-aerotolerant C. coli strains harbored the catalase-like protein gene, the gene was also present in a number of the aerosensitive strains. The Catalase like protein gene was found to be expressed in both aerobic and microaerobic conditions with a 2-fold higher gene expression detected in aerobic conditions for an aerosensitive strain. However, the exact function of the gene remains unclear and awaits further investigation. In conclusion, aerotolerant Campylobacter strains (especially C. coli) are prevalent in various retail meats. Further studies are needed to investigate whether the genes encoding catalase-like heme binding protein and putative transcriptional regulators in C. coli strains are involved in stress response.

Whole genome sequencing reveals extended natural transformation in Campylobacter impacting diagnostics and the pathogens adaptive potential

“…C. jejuni was shown to survive longer in liver juice 45 . Aerotolerant C. jejuni strains were identified 46 but also aerotolerant C. coli isolates were highly prevalent in other studies 47 . Survival in harsh environments might be a result of various factors and also dependent on the specific genomic background.…”

Current Status of <i>Campylobacter</i> Food Poisoning in Japan

“…Several reports have shown that some strains of C. jejuni are aerotolerant and may survive efficiently under aerobic conditions 24,30,40) , suggesting that aerotolerant strains may pose an increased risk in terms of food contamination and human infection. According to a study from Canada, approximately 36% of C. jejuni isolates from retail chicken meat are highly tolerant to aerobic conditions 30) and C. jejuni strains with increased aerotolerance survive longer on chicken meat than those sensitive to aerobic conditions 41) .…”

Detection of Campylobacter jejuni liver dissemination in experimentally colonized turkey poults

“…Food products containing chicken liver, including pâté, parfait, and mousse, were identified as sources of human campylobacter outbreaks ( Merritt et al., 2011 , Farmer et al., 2012 , Parry et al., 2012 , Centers for Disease Control and Prevention, 2013 , Edwards et al., 2014 , Scott et al., 2015 , Glashower et al., 2017 ). Of human concern, C. jejuni or Campylobacter coli have been isolated from chicken livers ( Barot et al., 1983 , Khalafalla, 1990 , Boukraa et al., 1991 , Wieliczko, 1994 , Baumgartner et al., 1995 , Fernandez and Pison, 1996 , Cox et al., 2006a , Cox et al., 2007 , Cox et al., 2009 , Strachan et al., 2012 , Harrison et al., 2013 , Firlieyanti et al., 2016 , McLauchlin et al., 2017 , Karki et al., 2018 ). Recent culinary trends, especially intentional undercooking of liver, may explain the increase of chicken liver products responsible for human campylobacteriosis.…”

“…Campylobacter may adapt to liver parenchyma to better survive in refrigerated poultry products, and affect its transmission to humans. Some strains of C. coli isolated from chicken livers are hyper-aerotolerant, more so than C. jejuni strains isolated from chicken livers ( Karki et al., 2018 ). Incubation of Campylobacter with retail chicken liver juice supports biofilm formation in C. coli and the survival of C. jejuni at 4°C ( Karki et al., 2019 ).…”