Purohit, J. H.KIRTIBHAI, PATEL HETALBEN2018-06-212018-06-212004http://krishikosh.egranth.ac.in/handle/1/5810054885Two isolates of Pasteurella multocida each from poultry, sheep, rabbit, buffalo and the vaccine strain (P52 strain) were studied for cultural, morphological and biochemical characterization, antimicrobial sensitivity, PCR-based detection and mouse pathogenicity of P. multocida field isolates. The heart blood and organs of the experimental mice were processed for reisolation of P. multocida. The heart blood and reisolated organisms from the experimental mice were subjected to PCRbased detection. All the test isolates were Gram negative, cocco-bacillary rods and produced non-haemolytic colonies on blood agar and failed to grow on MacConkey agar. All the isolates (100%) were positive for oxidase, catalase, indole production, nitrate reduction and fermentations of glucose, mannitol, sucrose and mannose while negative for citrate utilization and fermentation of maltose, arabinose, lactose, dulcitol, salicin and trehalose. The isolates (100%) were sensitive to enrofloxacin, flumequine, chloramphenicol and tetracycline, while nine isolates (90%) were sensitive to norfloxacin and cephalexin, two isolates (20%) were sensitive to penicillin G. All the isolates were (100%) resistant against sulphadiazine while four isolates(40%) were intermediate to penicillin G. Sixty per cent of P. multocida isolates were sensitive to Allium sativum, 40% sensitive to Ocimum sanctum, 20% sensitive to Zingiber officinale, 10% sensitive to Azadirachta indica, 10% sensitive to Curcuma longa. All the isolates were lethal to mice. Significant difference was observed in death time between species and between dilutions. Poultry isolates were found highly pathogenic to mice. Gross changes in mice were characterized by congestion and haemorrhages in most of vital organs. Histopathological lesions were characterized by mild to sever congestion, haemorrhages, and bacterial emboli. PM-PCR from reisolated colonies of P. multocida and gemomic DNA of test isolates were tested by PCR-based characterization, which revaled amplified product of approximately 465 bp size of all the P. multocida isolates, E.coli did not show amplification. Direct PCR from mice blood could not show any amplification.enVETERINARY MICROBIOLOGYCHARACTERIZATIONThesis