Molecular typing and phylogenetic analysis of Pasteurella multocida isolates from cattle and buffaloes of West Azerbaijan, Iran

Pasteurella multocida is a significant veterinary pathogen that infects cattle and buffaloes, causing respiratory and systemic diseases as well as significant financial losses. The genetic diversity of P. multocida must be understood to develop effective control methods. In order to inform disease control strategies, this work employed multilocus sequence typing (MLST) to investigate the genetic diversity and phylogenetic relationships of P. multocida isolates from cattle and buffaloes in Iran’s West Azerbaijan Province. Three hundred seventy-eight samples were collected from 200 cattle and 178 buffalo, including nasal swabs and lung tissues. The isolates were identified by culture, biochemical testing, and PCR for the kmt1 gene. MLST was performed on seven housekeeping genes (adk, est, pmi, zwf, mdh, gdh, and pgi) to determine genetic diversity. To evaluate the evolutionary relationships between isolates, phylogenetic analysis was done. Overall, P. multocida was found in 5.62% of buffaloes and 6% of cattle. The bacteria were found to be more common in nasal swabs (5.55%) than in lung tissues (0.26%). All isolates belonged to the ST-122 sequence. Based on a phylogenetic analysis, ST-122 was found to cluster with related types (ST63, ST460, ST473, and ST322). The findings of this study indicate the genetic homogeneity of P. multocida isolates from West Azerbaijan Province, which is most likely associated with one source or mode of transmission. The dominance of the ST-122 type indicates its potential role in the occurrence of cattle and buffalo infections in this region. These findings provide a basis for future epidemiological surveillance.