Antimicrobial and immunological studies on Pasteurella multocida and Mannheimia haemolytica recovered from calves affected with respiratory manifestations

Abstract

Pneumonic pasteurellosis is the main cause of severe respiratory tract infections incalves and causing great economic losses. The objective of this research was to studythe antimicrobial susceptibility of P. multocida and M. haemolytica and detection theeffect of Lysozyme and Nitric oxide; as immune parameters, on most importantbacteria causing pneumonic pasteurellosis in cattle calves. A total number of 406 deepnasal swabs and blood samples were collected from 406 bovine calves suffered fromrespiratory manifestations. Bacteriological examination revealed that the overallprevalence of both P. multocida and M. haemolytica was of 26.6%; 18.2% for P.multocida and 8.4%for M. haemolytica. P. multocida was singly isolated from 4.9% ofcases. While it was mixed with S. aureus, E. coli, Streptococcus spp., both S. aureus andE. coli, both S. aureus and Streptococcus spp. and both E. coli and Streptococcus spp.with percentages of 4%, 1.2%, 2.2%, 1.7%, 3.2% and 1.0%, respectively. Meanwhile,M. haemolytica was isolated as a single isolate from 1.7% of cases while it was mixedwith S. aureus, Streptococcus spp., both S. aureus and Streptococcus spp. and both E.coli and Streptococcus spp. with percentages of 2.7%, 1.2%, 2.5% and 0.2%,respectively. The in in-vitro sensitivity testing of all isolates showed high susceptibilityto Fluoroquinolones and cephalosporins. On the other hand, high resistances wereobtained against tetracyclines, penicillins and aminoglycosides. On the immunologicallevel, the data of the existing research show that all respiratory affected calves recordsignificant elevation of nitric oxide level in compare with normal control calves.However, all infected calves elucidate significant reduction of lysozyme activity.