Molecular Subtyping and Source Attribution of Campylobacter Isolated from Food Animals

Campylobacter spp. commonly cause gastrointestinal illness in humans. Poultry meats have long been considered the predominant source of these infections, but few in-depth Campylobacter source attribution studies have been completed. We analyzed more than 1,300 Campylobacter isolates recovered from a number of animal and food sources, including dairy and beef cattle, pigs, poultry, and retail poultry meat, and compared them with Campylobacter isolates recovered from human clinical samples. Each isolate was subtyped using pulsed-field gel electrophoresis (PFGE) with SmaI and queried against the Centers for Disease Control and Prevention PulseNet database to identify human isolates with indistinguishable patterns. Half (49.5%) of the PFGE patterns from poultry animal and retail meat isolates were indistinguishable from patterns of at least one human isolate. Among the isolates from beef and dairy cows, 56.6 and 65.0%, respectively, of their PFGE patterns were indistinguishable from those of human isolates. Only a small portion of the PFGE patterns of Campylobacter isolated from pigs (9.5%) were found to have PFGE patterns in common with human isolates. These data imply that cattle may be larger contributors to Campylobacter infections than previously recognized and help further our understanding of potential sources of human campylobacteriosis.