Abstract:

[Objective] This study aimed to determine the causative agent of an infectious disease case on a chicken farm in Datong County of Qinghai Province, and to provide reference for prevention and control of Proteus mirabilis infection. [Method] The samples of liver and spleen tissues and cloacal swabs were aseptically collected and inoculated on common nutrient agar and SS agar for bacterial culture, isolation, and purification. Suspected colonies were selected for Gram staining and microscopic examination. The isolated colony were then inoculated into the commercial biochemical reaction test tube for biochemical identification. The isolate was molecularly confirmed by 16S rDNA and tuf specific gene PCR amplification and sequencing. Chicks were challenged with the isolate for pathogenicity test. The K-B method was used to assess the susceptibility of the isolate to 27 antibiotics. [Result] The isolated strain was pleomorphic bacilli （short or long rod-shaped）, and its biochemical traits were consistent with Proteus mirabilis. A 16S rDNA fragment with length of 1 400 bp was successfully amplified by PCR assay, and sequence alignment revealed that it shared the highest homology to Proteus mirabilis at 99.9%. The pathogenicity test demonstrated that the isolate was pathogenic to chicks. The antimicrobial susceptibility test revealed that the isolate was highly sensitive to piperacillin, cefepime and cefotaxime, moderately sensitive to ciprofloxacin and ogmentin, and resistant to ampicillin, amoxicillin and cefazolin. [Conclusion] The strain of Proteus mirabilis isolated from chicken had strong pathogenicity and showed resistance to some antimicrobial agents.

Key words: chicken, Proteus mirabilis, isolation and identification, antimicrobial susceptibility test