Prevalence and Antibiotic Resistance Pattern of Mannheima haemolytica and Pasteurella multocida Isolated from Cattle Lung Samples from an Industrial Abattoir: A Study from Northeastern Iran

Bovine respiratory disease (BRD) is still one of the most important infectious diseases in dairy farms. Pasteurella multocida and Mannheimia hemolytica are the main bacterial pathogens of BRD.

This study aimed to determine the prevalence and pattern of antibiotic resistance of M. hemolytica and P. multocida isolated from lung samples of cattle slaughtered in an industrial abattoir in Golestan province, northeastern Iran.

Samples were taken from diseased and normal-appearing lungs of cattle slaughtered in an industrial abattoir. The samples were processed bacteriologically for the isolation of both Pasteurellaceae species. The isolates were identified by cultural and biochemical tests, and polymerase chain reaction (PCR) technique. Antimicrobial susceptibility of the isolates was determined using the Kirby–Bauer disc diffusion method.

A total of 120 samples were collected. The bacteriological examination of the samples resulted in the isolation of 36 (30%) M. hemolytica and P. multocida strains. Of the isolates, 14 (11.6%) and 22 (18.3%) were positive for P. multocida and M. hemolytica, respectively. Clear difference was observed between the populations of M. haemolytica recovered from apparently healthy lung tissues versus pneumonia samples. All the isolates were susceptible to tulathromycin, and the highest resistance was observed to penicillin and erythromycin. Multiple drug resistance was observed in both Pasteurellaceae species.

The results highlight the importance of continued surveillance of BRD pathogens in monitoring their antibiotic resistance patterns to update treatment protocols. Surveillance studies are also necessary to develop policies for limiting the spread of resistance.