Typing of Mannheimia haemolytica isolates isolated from respiratory tract and investigation of virulence genes

Abstract

In this study, it was aimed to determine the biochemical properties, distribution of important virulence genes of Mannheimia haemolytica isolates identified from the respiratory tracts of sick and healthy cattles and sheeps. 48 (87.3%) Mannheimia haemolytica isolates from naso-pharyngeal and trachea-bronchial swaps were identified as Mannheimia haemolytica by Real Time-PCR. According to the differences in arginine and sorbitol tests, 4 different biochemical profiles were determined in the isolates examined. Three virulence gene profiles were detected in the isolates examined by Real-Time PCR. 37.5%, 33.3%, 12.5% of the isolates examined were identified as I, III and II, respectively. While all virulence-related genes were identified in the isolates with virulence gene profile II, it was determined that there were no nmaA gene in profile I isolates and nmaA and tbpB genes in profile III isolates. At the same time, it was determined that biochemical profile II was associated with disease cases and this was related to arginine negativity. In addition, it was determined that isolates with virulence gene profile I were associated only with biochemical profile I and that this was due to arginine negativity, whereas the relationship between arginine positive isolates and virulence gene profile III was found to be significant. As a result; arginine negativity and gcp, gs60, tbpB, lktC, adh positive, nmaA negative isolates may be the epidemiological criteria that can be used to differentiate commensal and pathogen Mannheimia haemolytica isolates and new studies on the subject should be done.