Isolation and identification of Mannheimia haemolytica and Pasteurella multocida from symptomatic and asymptomatic sheep and their antibiotic susceptibility patterns in three selected districts of north Gondar zone, Gondar Ethiopia

BACKGROUND: Small ruminants are the most numerous of man's domestic livestock. Although sheep represent a great resource for Ethiopia, the net rate of productivity per animal is very low due to many factors including respiratory disorders. OBJECTIVES: The objectives of this work were to isolate and identify M. haemolytica and P. multocida as well as to assess the antibiotic susceptibility patterns of these isolates. Nasal swab samples were collected aseptically by using 70% alcohol as a disinfectant. METHODS: A cross‐sectional study was conducted in three selected districts of the north Gondar zone, Ethiopia. RESULTS: From 148 samples collected in 94 (63.5%) asymptomatic and 54 (35.5%) symptomatic sheep, a total of 23 were isolated successfully based on cultural, staining, and biochemical characteristics. Of these isolates, 18 (78.3%) and 5 (21.7%) were M. haeimolytica and P. multocida, respectively. Compared with the total animals examined, the proportion of M. haeimolytica and P. multocida were 12.16 % (n = 18) and 3.38% (n = 5), respectively. All of the isolates were subjected to a panel of 8 antibiotic discs for sensitivity testing. Of the tested antibiotics, chloramphenicol (100%), gentamicin, and tetracycline (82.6%) each and co‐trimoxazole (60.8%) were found to be the most effective drugs whereas, both species were completely resistant to vancomycin and showed a very low degree of susceptibility for the rest drugs. CONCLUSIONS: In conclusion, M. haemolytica was found to be the predominant isolate in all host‐related factors and most of the antibiotics were not fully effective against the isolates. Hence, treatment and/or vaccination of ovine pneumonic pasteurellosis should be emphasised to M. haeimolytica using the most effective drugs along with appropriate herd management practices.