Identification of serotypes Pasteurella multocida and Mannheimia haemolytica from cattle and sheep in central Ethiopia

Abstract Background: Pneumonic pasteurellosis is a multi-factorial respiratory disease of cattle and sheep caused by combination of etiologic agents; hence, reliable information is needed on the species or serotypes of bacterial agents for optimum control of the disease. This study was conducted with the objectives of identification of bacterial agents causing pneumonic pasteurellosis in cattle and sheep and identify serotypes of P. multocida involved. Methods: Bacteriological and molecular methods were used on 176 pneumonic lungs (93 cattle and 83 sheep) collected from abattoirs and 604 nasal swabs collected from 302 cattle and 302 sheep presented to Asella, Holota and Sheno veterinary clinics. Results: Twenty-five percent, 26.5% and 23.5% of nasal swabs collected from cattle and sheep from Asella, Holota and Sheno, respectively, were positive to one or more species of Pasteurella, Mannheimia and Bibersteinia. Mannheimia haemolytica was the predominant bacteria isolated at all sites. The isolation of these bacterial species was associated with age and pneumonic status of animals and management system. Young animals were more likely to yield positive results than adults (OR = 1.56; 95 % CI: 1.02, 2.38). Similarly, isolation of the three bacterial species was more frequent in animals with signs of pneumonia than those animals without signs of pneumonia (OR = 4.67; 95 % CI: 3.03, 7.19) and from animals under intensive management system than those animals kept under extensive management system (OR = 2.46; 95 % CI: 1.12, 5.39). Out of the total of 176 pneumonic lungs examined isolation was done from 48 (27.27 %) of them. Mannheimia haemolyitica was the predominant species isolated from pneumonic lungs. The identity of P. multocida and M. haemolytica isolated was further confirmed using PCR. Pasteurella multocida serotypes A1 and A3 and M. haemolytica serotype A1 were the predominant serotypes identified. Conclusion: This study revealed that M. haemolytica, P. multocida and B. trehalosi are commonly circulating in cattle and sheep originated from various parts of the country. It is also interesting that the serotypes of P. multocida and M. haemolytica identified in the present study are those that are already proven to cause pneumonia in ruminants.