Prevalence and Distribution of Thermotolerant Campylobacter Species in Poultry: A Comprehensive Review with a Focus on the Factors Affecting the Detection and Enumeration of Campylobacter jejuni and Campylobacter coli in Chicken Meat

It is well known that the strong-evidence foodborne outbreaks of human campylobacteriosis are associated with the consumption of raw or incompletely thermally processed poultry meat, whereas broilers act as the main reservoir for Campylobacter species. Campylobacter jejuni and Campylobacter coli are the two main species of campylobacters detected in chicken meat, while they account for almost 90% of the reported cases of campylobacteriosis in humans. Over 80% of these cases are attributed to C. jejuni and about 10% of them are due to C. coli. Therefore, until recently the dominance of C. jejuni against all other Campylobacter spp. isolated from chicken meat samples was well-established and unquestionable. Lately, however, C. coli has been increasingly recovered from chicken meat to such an extent that it is now evident that it often comprises the dominant species among the identified campylobacters in the meat samples. This work attempts for the first time a detailed review of the literature to deepen into this noteworthy epidemiological swift in the prevalence of C. jejuni and C. coli, along with the distribution of Campylobacter spp. in chicken meat. Factors such as the sampling method followed for screening campylobacters in broiler carcasses (e.g., swabs or carcass rinsates, skinned or skinless meat excised samples) and part of the animal carcass from which the sample is obtained (e.g., neck, breast, leg), seasonality of sampling (summer vs. winter) and environmental conditions (e.g., rainfall, relative humidity) at the farm level, the isolation procedure (enumeration or detection) and pathogen identification (biochemical or molecular), the enrichment and plating isolation media (e.g., Bolton vs. Preston broth, charcoal-based vs. chromogenic agars), as well as the biofilm-forming ability of different campylobacters, highlight the multivariate dimension of the phenomenon and are thoroughly discussed in the present review.