Osteomyelitis in a slaughter turkey flock caused by Yersinia pseudotuberculosis sequence type ST42.

A Yersinia pseudotuberculosis outbreak was diagnosed in a male turkey flock in Finland. Y. pseudotuberculosis is a quite rare zoonotic bacterium, which typically causes enteritis in humans and sudden death in animals. In this study, osteomyelitis was diagnosed in small, lame, 11- to 12-wk-old male turkeys. Lameness and slower growth among the turkeys was observed on the farm. During pathological examination, multiple lesions were found in the metaphyseal and physeal areas of the femurs, tibiotarsi, and tarsometatarsi, with multifocal to coalescing mixed heterophilic/granulomatous necrotizing osteomyelitis. Y. pseudotuberculosis was isolated from the femoral and tibiotarsal bones or from the joints of six lame turkeys sent for necropsy. The isolation required homogenizing of lesion tissue in phosphate-mannitol-peptone broth, which was cultured directly - and, if needed, after cold enrichment - on selective cefsulodin-irgasan-novobiocin agar. Whole-genome sequencing was used for identification and typing. All isolates belonged to bio/serotype 1/O:1a and sequence type ST42 (Achtman scheme), which is commonly reported in both human and animal Y. pseudotuberculosis infections in Europe. The isolates from all six turkeys showed only one to two allele differences in the core genome comparison, indicating a common source of infection. All asymptomatic turkeys were slaughtered at the age of 17 weeks. Whole and partial carcass condemnation rates at the slaughterhouse were high, but no macroscopic changes in the skeletal system were found, showing that food chain information is essential. This study confirms earlier findings that Y. pseudotuberculosis can cause osteomyelitis in fattening turkeys, leading to lameness. Food chain information is essential for slaughterhouse operations, to protect the workers and emphasize good working hygiene during slaughter.