Identification of Pasteurella multocida isolates of ruminant origin using polymerase chain reaction and their antibiogram study

A total of 100 isolates of Pasteurella multocida from various ruminant species (cattle, buffalo and sheep) belonging to different parts of country were identified using Pasteurella multocida-PCR (PM-PCR) and capsular PCR assays. PM-PCR revealed an amplicon of approximately 460 bp in all the isolates tested. As regards capsular PCR, 36 of 38 cattle isolates and 30 of 34 buffalo isolates were found to belong to capsular serogroup B whereas rest of the cattle and buffalo isolates belonged to serogroup A of P. multocida. In case of sheep, a total of 26 out of 28 isolates were positive for serogroup A specific PCR while remaining 2 amplified a PCR product specific for serogroup F of P. multocida. All the isolates were subjected to antibiotic sensitivity testing using 17 different antibiotics. Enrofloxacin was found to be most potent antibiotic as it was effective against 94% of the isolates followed by ofloxacin (93%), chloramphenicol (93%), doxycycline (89%), tetracycline (86%) and ciprofloxacin (84%). Vancomycin, bacitracin and sulfadiazine were ineffective against P. multocida isolates showing 84%, 75% and 82% resistance, respectively. Further, the antibiogram also revealed the development of resistance against multiple drugs among various isolates of the organism.