الفهرس 
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Abstract
In the present study, bacteriological and molecular studies were applied on P. multocida in sheep and goats under desert condition. The present work was done on 1053 small ruminants (766 sheep and 287 goats) in an attempt to throw spotlights upon the rate of P. multocida isolation among these animals, effective antibacterial drugs against some of field isolates and comparing a molecular method with traditional culture method for diagnosis of P. multocida infection.
Bacteriological examination of 1053 specimens collected from living, slaughtered or dead apparently healthy or diseased sheep and goats revealed the isolation of 107 P. multocida isolates with recovery rate of 10.16%. It appeared that the highest rate of isolation was found among the samples from slaughtered and dead animals with the isolation of 28 P. multocida out of 243 samples (11.5%). The isolation rate was comparatively low in samples from living animals (39 out of 523; 7.4%). The rate of P. multocida isolation in the diseased sheep reached (36 out of 238; 15.1%) which was comparatively higher than those from apparently healthy ones (31 out of 528; 5.8%).
The examination of 287 samples collected from apparently healthy (191) and diseased (96) (living, slaughtered or dead) goats for P. multocida revealed the isolation of 40 positive isolates with recovery rate of (13.9)%.
It appeared that the highest rate of isolation was found among the samples from slaughtered and dead animals with the isolation of 13 P. multocida out of 60 samples (21.6%). The isolation rate was comparatively low in samples from living animals (27 out of 227; 11.8%). The rate of P. multocida isolation in the diseased sheep reached 22 out of 96 (22.9%) which was comparatively higher than those from apparently healthy ones; 18 out of 191 (9.4%).
Thirty P. multocida isolates (7 from nasal swabs of apparently healthy, 10 from nasal swabs of diseased and 13 from pneumonic lungs cases) were examined for their Pathogenicity against white Albino mouse. All the isolates (19 from sheep and 11 from goats) found to be lethal to mice.
Eighty eight P. multocida were serotyped into: serogroup A (serotypes 1, 3, 4) and serogroups B (serotype 2) and serogroups D (serotype 1), while nineteen isolates were untyped with percentage of (17.9%) and (17.5%) in sheep and goats respectively.
Detection of antibody titers in the serum samples collected from infected and contact animals by IH revealed that, the antibody titer against P. multocida was higher in the infected animals than the contact apparently healthy sheep and goats. Detection of antibody to P. multocida in sheep and goats sera was applied by using indirect ELISA. Three hundred serum samples were collected from 210 sheep, 90 goats including apparently healthy and respiratory affected ones. The infected animals showed higher titer than the contact apparently healthy animals.
The antibiogram profile of thirty P. multocida isolates revealed that the potential antibiotics against P. multocida were Erythromycin (28/30) 93.3%, Rifampicin (27/30) 90% and Ciprofloxacin (26/30) 86.6%, where the less effective antibiotics were Oxytetracycline 8/30 26.6% and Amoxicillin (4/30) 13.3%.
P. multocida species specific PCR (PM–PCR) assay identified P.multocida by amplifying 460 bp DNA fragment within KMTI gene. The species-specific PM-PCR assay employed during the study correctly identified a total of 20 clinical samples found to be positive for P. multocida following isolation and identification by bacteriological methods, 20 direct nasal swabs, 20 direct lung tissue samples. The results of the current study indicated that PM-PCR assay can be used to identify P. multocida. PCR assay can provide rapid, sensitive, and specific identification of P. multocida isolates with relatively uncomplicated methodology from isolated culture or even from direct samples (nasal swabs or lung tissues).
Amplified DNA products of ~1044, ~760 and ~657 bp corresponding to P. multocida capsular groups A, B and D were observed, respectively. The band sizes of ~511 and ~854 bp expected to be produced corresponding to P. multocida capsular serogroups E and F, respectively were not detected.
Results of OmpH gene detection by PCR, the primers successfully amplified thirty P. multocida isolates with the amplification generated a product of about 1.2 K.b.