Application of polymerase chain reaction (PCR) in diagnosis of some pathogenic E.coli strains isolated from natural cases of colibacillosis in chickens [electronic resource].

Includes reference.

Seventy- four and sixty E.coli isolates were recovered from the internal organs of colibacillosis infected broiler chickens, and cloacal contents of apparently healthy broiler chickens,respectively. The obtained E.coli isolates were biochemically identified and serologically serotyped to different 0, serogroups. Virulence testing of the obtained serotypes was done on one day old chicks. Antimicrobial susceptibility testing of the obtained strains was done against ten of the most commonly used antimicrobial drugs. Further attempts were made to characterize the obtained E.coli serogroups using polymerase chain reaction technique (PCR) of cvi colicine V immunity gene. The obtained results showed that : Six O,serogroups (01, 02, 035, 078, 080 and 0157) were only isolated from the internal organs of the diseased broilers. Twelve O, serogroups (044, 088, 091, 092,098, 0109, 0111, 0114, 0119, 0145, 0150 and 0158) were only isolated from cloacal contents of apparently healthy birds. Only one common 0' serogroups (073) was isolated from both healthy and diseased groups. Only, the isolates from colibacillosis cases were highly virulent, while, those from cloacal contents of healthy birds were non-virulent. Hundred percent of the obtained E.coli serogroups were susceptible for enrofloxacin, norofloxacin, ciprofloxacin and chloramphenicols. The PCR test was performed on one isolate of each of the 19 E.coli strains. A single band with the expected size of 760 bp was obtained with 17 strains (89.47 %). Only, two isolates from apparently healthy birds did not contain cvaC gene

Summary in Arabic.

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