Investigation of Biotype, Genotype and Virulence Associated Genes in Pasteurella Multocida Capsular Type a Strains From the Respiratory Tract of Cattle and Their Relationship With Disease Cases

Abstract

Pasteurella (P.) multocida, which causes respiratory disease in cattle, can also be found commensally in the upper respiratory tract. Therefore, it is epidemiologically important to determine the possible difference between pathogenic and commensal strains for the diagnosis of the disease. In this study, phenotypic and genotypic characteristics and virulence associated genes of P. multocida capsular type A strains isolated from the respiratory tract of sick and healthy cattle were investigated. Also, the relationship between the disease status of animals and the characteristics of the isolates were evaluated. Total of 51 P. multocida capsular type A strains were biotyped and genotyped by using commercial bacteria identification kits and PCR-fingerprint, respectively. Four major biotypes generated from xylose and sucrose test results were detected in 39 (76.47%) isolates. Eleven different biotypes were detected in the remaining 12 isolates (23.53%), which were separated from the 4 major biotypes by mannitol, indole, sorbitol, nitrate, VP, lactose, arabinose, salicin, and rhamnose test. Four genotypes were detected in P. multocida isolates and most of them (90.2%) had genotype I profile. Virulence associated genes, such as hgbA, exbB, exbD, tbpA, ptfA, hsf-2, tadD, nanB, nanH, pmHAS, sodA, sodC, and oma87 were detected in all isolates whereas hgbB, toxA, and hsf-1 genes were not found by PCR. PfhA gene were found in 49 isolates (96.07%) but, ompH gene could be detected only in 10 (18.86%) isolates. The findings of the study indicated that P. multocida capsular type A strains generated as xylose positive/sucrose negative (biotype II) and genotype II may be associated with respiratory diseases of cattle. However, ompH gene was observed to be associated with sucrose negative isolates, but not with disease cases. As a result, it was concluded that xylose positive/sucrose negative biotype and genotype II determined in P. multocida capsular type A strains isolated from respiratory diseases of cattle, might be important epidemiological criteria in the differentiation of commensal and pathogenic isolates.