Antimicrobial Resistance in Pasteurella multocida Type B and Mannheimia haemolytica Isolates in Cattle and Buffaloes

Hemorrhagic septicemia is a fatal septicemic disease in cattle and buffaloes in tropical countries. Young animals were more susceptible, and buffaloes were shown high percentage of mortality than cattle. Mannheimia haemolytica was described as an opportunistic pathogen in cattle and buffaloes and concurrent infection were also reported with primary other diseases. Only few studies were published in the country on these two bacterial organisms, information on antimicrobials resistance was limited in local herds. Lack of clinical breakpoints or host specific clinical breakpoints has been identified as a limiting factor to identify the phenotypic resistance. The objective of the study was to confirm the Pasteurella multocida isolates which received from clinical cases of hemorrhagic septicemia in the country. The second objectives were to determine phenotypic antimicrobial resistance in Pasteurella multocida clinical isolates and to compare with phenotypic antimicrobial; resistant phenotypes of Mannheimia haemolytica.

The clinical isolates of Pasteurella multocida were received (n=29) from the regional laboratories in the country from 2017-2019. Manhenimia hemolytica (n=49) was collected from our laboratory collection which were sampled from cattle and buffaloes from dry zone of the country previously. The resistance percentage of were Pasteurella multocida 72% and 29% for ciprofloxacin and cefotaxime. Resistance of cefotaxime was shown in Pasteurella multocida and none in Manhenimia hemolytica. Resistances to ciprofloxacin were shown high in Pasteurella multocida and low in Manhenimia hemolytica. Resistance to amoxicillin and clavulanic acid and tetracycline were found in both organisms. Phenotypic antimicrobial resistance was reported low in Pasteurella multocida and Manhenimia hemolytica in cattle and buffaloes. In conclusion, usage of sulfamethoxazole and quinolone group of antimicrobials for the pasteurellosis such as enrofloxacin, ciprofloxacin may have negative impact due to the high frequency of resistance observed.