Isolation, identification and antimicrobial susceptibility of Proteus vulgaris isolated from Ictalurus punctatus

Abstract:

[Objective] We isolated, identified and tested antibiotic sensitivity of a pathogen from naturally infected Ictalurus punctatus. [Methods] The pathogenic bacteria were isolated and purified from lesions, liver, kidney and spleen of Ictalurus punctatus. Strain k1 was identifies using the biochemical identification and 16S rRNA gene sequence determination. The artificial infection test was done, and antimicrobial susceptibility was tested by disc diffusion method. [Results] Strain k1 was the pathogen of Ictalurus punctatus, and the LD50 of the isolates was 2.82×105 CFU/g. According to morphological and biochemical characteristics as well as the result of 16S rRNA gene sequence analysis, strain k1 was identified as Proteus vulgaris. Strain k1 was susceptible to 12 agents including ciprofloxacin, cefazolin, cefadroxil and other antibiotics. Meanwhile, it showed resistance to oxacillin, amoxicillin, furazolidone and other 7 antibiotics. [Conclusion] our results demonstrated that Proteus vulgaris was the pathogen causing high mortality in Ictalurus punctatus, and the disease may prevent by using drugs such as gentamicin and neomycin in fisheries.