羊から分離されたグルコシダマンネミアの特徴と病原性

Bacteria of the genus Mannheimia are major pathogens of respiratory diseases in ruminants and pose a significant threat to the global ruminant industry. However, the biological characteristics and pathogenic mechanisms of Mannheimia glucosida remain unclear. In this study, we isolated five strains of M. glucosida, which specifically hydrolyzed esculin, from sheep with respiratory disease in China. All five strains of M. glucosida were found to encode the adhesion-related gene adh and the anti-phagocytosis-related gene plpD, as determined by a virulence gene assay. Moreover, all M. glucosida isolates were resistant to streptomycin. Phylogenetic analysis based on 16S rRNA, infB, and sodA genes showed that the sodA gene could be a valuable indication for the analysis of bacterial genetic evolution in the genus Mannheimia. By mouse modeling, M. glucosida D251 was further found to cause multiorgan damage with an LD₅₀ of 1.35 × 10⁶ CFU. Meanwhile, by combining whole genome sequencing with bioinformatic analysis, we found that the D251 genome encodes a large number of virulence and drug resistance genes. Finally, we established a highly sensitive and specific PCR assay for M. glucosida. Collectively, these results indicate that M. glucosida may be an important pathogen in respiratory disease in sheep in China and provides a theoretical basis for the clinical diagnosis and treatment of this disease.