Genome features and antimicrobial resistance of Trueperella pyogenes isolated from deceased farmed white-tailed deer ( Odocoileus virginianus ) in Florida

Trueperella pyogenes is a gram-positive, facultatively anaerobic bacterium known to cause infections in both domestic and wild animals, including white-tailed deer (WTD; Odocoileus virginianus ). However, limited studies have focused on its impact on farmed WTD. In this study, we aimed to explore the demographic features, antimicrobial resistance (AMR) profiles, and virulence factors of T. pyogenes isolated from farmed WTD in Florida. Between 2016 and 2023, we managed 831 deceased farmed WTD cases. Specimens from 715 animals were subjected to bacterial culture. T. pyogenes was isolated from 147 (20.6%) animals, ranking as the second most frequently isolated bacterial pathogen. All T. pyogenes -infected animals exhibited pneumonia. T. pyogenes infection cases were notably more prevalent during summer and fall. Between September 2020 and May 2022, all available T. pyogenes isolates ( n = 37) recovered from various specimen types from 30 diseased deer were included and analyzed using whole-genome sequencing and phylogenetic approaches. The results revealed substantial single-nucleotide polymorphism (SNP) diversity within the core genomes of the T. pyogenes strains. Antimicrobial resistance profiling showed that tetracycline resistance genes, particularly tetW , predominated, while genes associated with resistance to aminoglycosides, sulfonamides, and other tetracyclines were detected sporadically. Genes for several virulence factors were also identified, including pyolysin ( plo ), collagen-binding protein ( cbpA ), and various adhesion molecules. These findings highlight the importance of disease management strategies, including surveillance and targeted antimicrobial use, to mitigate T. pyogenes transmission in farmed WTD. Broader surveillance using non-postmortem clinical specimens and culture-independent approaches is needed to better understand its epidemiology.

IMPORTANCE

Trueperella pyogenes is an opportunistic pathogen that has likely been underrecognized in its role in white-tailed deer health. Our demographic and genomic analysis of T. pyogenes isolated from deceased farmed white-tailed deer in Florida identified seasonal patterns, frequent association with pneumonia, and substantial genomic diversity among isolates. These findings highlight the need for enhanced surveillance, improved diagnostic approaches, and preventive measures to better understand and manage T. pyogenes infections in farmed and free-ranging cervid populations. By characterizing the demographic and genomic features of T. pyogenes in this understudied host system, this study provides a foundation for future research on pathogen ecology, disease surveillance, and cervid health management, including monitoring in settings where farmed deer may interact with surrounding wildlife.