Seroprevalence, isolation, comprehensive characterization, and pathogenicity of Clostridium perfringens strain from yak in Xizang, China

Clostridium perfringens is an anaerobic, toxin-producing pathogen responsible for enteric and systemic disease in livestock, yet its ecology in high-altitude yaks remains poorly understood. We conducted a comprehensive investigation covering eight counties of the Xizang Autonomous Region between July 2021 and October 2024. Serological screening of 922 unvaccinated yaks revealed an individual-level antibody prevalence of 0.76% (95% CI: 0.4-1.6) and a herd-level prevalence of 25% (95% CI: 12.7-43.4). Multivariable logistic regression identified residence below 4000 m as the sole significant risk factor (adjusted OR = 8.75; 95%CI: 1.3-56.8; P = 0.04). From seven seropositive animals, one representative isolate CPTibet-Y1 was obtained and subjected to detailed phenotypic, genomic and virulence analyses. Phenotypic profiling confirmed classic biochemical traits of C. perfringens, while 16 S rRNA, Toxin gene PCR typing and whole-genome sequencing classified the strain as toxin type A, harboring Toxin gene cpa, but lacking cpb, etx, iap, cpe and netB. Antimicrobial resistance profiling revealed broad-spectrum resistance encompassing sulfonamides, lincosamides and fluoroquinolones, underpinned by six acquired resistance determinants. In a murine infection model, intraperitoneal challenge with 5 × 10⁷ CFU resulted in 100% lethality within 48 h accompanied by severe intestinal necrosis, hemorrhage and systemic pathology. This study provides unequivocal evidence for the presence of multidrug-resistant, hypervirulent type A strains on the Qinghai-Tibet Plateau, underscoring the need for enhanced surveillance and targeted control strategies in yak-farming communities.