Analysis of Campylobacter jejuni Subtype Distribution in the Chicken Broiler Production Continuum: a Longitudinal Examination To Identify Primary Contamination Points

ABSTRACT

Significant knowledge gaps exist in our understanding of Campylobacter jejuni contamination of the poultry production continuum. Microbiological surveillance and genotypic characterization were undertaken on C. jejuni isolates longitudinally recovered from three poultry farms (weekly samples), the abattoir at which birds were processed, and at retail over a 542-day period in southwestern Alberta, Canada, as a model location. Subtypes were compared to concurrent isolates from diarrheic humans living in the study region. Barn outbreaks in broiler chickens occurred infrequently. Subtypes from colonized birds, including clinically relevant subtypes of C. jejuni, were recovered within barns and from subsequent production stages. When C. jejuni was detected in barns, most birds rapidly became colonized by a limited number of subtypes late in the cycle. However, the diversity of subtypes recovered from birds in the abattoir increased substantially. Moreover, birds deemed free of C. jejuni upon exit from the barn became contaminated within the abattoir environment, and a high prevalence of meat at retail was contaminated with C. jejuni, including subtypes that had not been previously observed in the barns. The observed increase in prevalence of contamination and diversity of C. jejuni subtypes along the chicken production continuum indicates that birds from a relatively small number of barns contaminate transport trucks and the abattoir with C. jejuni strains, which are collectively transferred to poultry within the abattoir and conveyed to and persist on retail products. We conclude that the abattoir was the primary contamination point of poultry by C. jejuni but only a subset of subtypes were a high risk to human beings.

IMPORTANCE The longitudinal examination of Campylobacter jejuni subtypes throughout the broiler production continuum is required to determine transmission mechanisms and to identify potential reservoirs and the foodborne risk posed. We showed that a limited number of C. jejuni subtypes are responsible for infrequent outbreaks in broilers within production barns and that colonized birds from a small number of farms are introduced into the abattoir where a high prevalence of carcasses are subsequently contaminated with a diversity of subtypes, which are transferred onto poultry in retail settings. However, only a subset of strains on poultry was determined to be clinically relevant. The study findings showed that resolving C. jejuni at the subtype level is important to ascertain health risks, and the knowledge obtained in the study provides information to mitigate clinically relevant subtypes to reduce the burden of campylobacteriosis.