Abstract:

[Objective] This study was conducted to identify the pathogenic bacteria isolated from the feces of diarrheal piglets in a farm in Xinjiang, and to understand their biological characteristics. [Method] Four faecal samples were collected from the diarrheal piglets in this farm, and the bacteriological culture technology and PCR assay were used to isolate and identify the bacterial pathogens. In addition, the antimicrobial susceptibility test and virulence gene detection were carried out for the isolated strains. [Result] After the bacteriological culture, three suspected strains were obtained. On xylose-lysine deoxycholate agar medium, the colonies were pale yellow with smooth and shiny surroundings as well as a black center. Gram stain demonstrated that they were short-rod-shaped Gram negative bacteria with blunt round ends. The SSU rDNA sequences of the three isolated strains had 100% homology with the SSU rDNA sequence of a Proteus mirabilis strain isolated from Caracal caracal in Guangdong Province, China. Combining morphological observation and SSU rDNA sequence analysis, the three obtained isolates, designated as NO.1, NO.2 and NO.3 strains, were identified as Proteus mirabilis. The three Proteus mirabilis isolates were resistant to eleven of the twelve antimicrobial agents, including norfloxacin, midecamycin, erythromycin, etc. The NO.2 and NO.3 strains were susceptible to cefoxitin, and the NO.1 strain was intermediate to cefoxitin. All the three isolates harbored seven virulence genes of ureC, pmfA, zapA, mrpA, atfA, atfC, and ucaA. [Conclusion] The three Proteus mirabilis strains isolated from piglets had multiple antimicrobial resistance and carried multiple virulence genes, indicating that Proteus mirabilis was one of the pathogens causing diarrhea in piglets. Attentions should be paid in the rational use of antibiotics.

Key words: Proteus mirabilis, antimicrobial resistance, virulence gene, diarrhea, piglet