Molecular Characterization and Prevalence of Hypervirulent and Multidrug-Resistant Klebsiella pneumoniae in Mastitis of Bactrian Camels from Xinjiang, China

Aims The escalating prevalence of multidrug-resistant (MDR) and hypervirulent (hv) Klebsiella pneumoniae ( K. pneumoniae ) strains represents a significant threat to both animal and human health globally. In Xinjiang, China, where Bactrian camels are an economically important livestock and human interaction with camel products is increasing, this study aimed to characterize the virulence, antibiotic resistance, and potential public health implications of K. pneumoniae isolates associated with camel mastitis. Results A total of 14 K. pneumoniae strains were isolated from camel milk, milker hand swabs, and environmental samples. Antimicrobial susceptibility testing revealed widespread MDR, with 100% of isolates resistant to β-lactams, aminoglycosides, macrolides, lincosamides, and glycopeptides. PCR analysis identified multiple acquired resistance genes. Multilocus sequence typing (MLST) revealed diverse sequence types, including ST42, ST4089, ST297, and ST495, with ST495 being the dominant type. Virulence gene profiling confirmed the presence of various virulence-associated genes. Pathogenicity assays in mice and rabbits demonstrated high virulence in ST495:KL121 strains. Notably, ST495 was isolated from camels, dairy workers, and environmental samples, indicating a potential transmission cycle between these reservoirs. Conclusion This study underscores the presence of highly MDR and potentially virulent K. pneumoniae strains linked to camel mastitis in Xinjiang. The identification of ST495:KL121 strains, exhibiting both hypervirulence and multidrug resistance, suggests the emergence of "superbug" characteristics and poses a substantial public health risk. These findings emphasize the critical need for intensified surveillance and robust control measures targeting K. pneumoniae in camel farming environments within the region to effectively mitigate the impact on both animal and human health.