Isolation,identification,and virulence gene detection of Escherichia coli from fox and raccoon dog

Abstract:

[Background] Frequent occurrence of pneumonia in foxes and raccoon dogs has resulted in huge economic losses for farmers.[Objective] In order to investigate the causes of pneumonia attacking foxes and raccoon dogs in Heilongjiang,Jilin,Hebei,and Shandong provinces,we isolated,identified,and characterized the pathogenic bacteria.[Methods] The bacteria were isolated aseptically from the lung tissues of diseased foxes and raccoon dogs.Gram staining,biochemical test,PCR identification of specific genes,susceptibility test by disk diffusion method,virulence gene detection,and mouse pathogenicity test were then conducted for the isolates.[Results] All the 136 isolates were Gram-negative bacilli and were identified as Escherichia coli based on biochemical characteristics and specific gene PCR.The isolates had multiple drug resistance and 29 virulence gene combinations.The main virulence genes were yijP,fimC,fimH,fyuA,iutA,papC, irp2,and astA.The isolates carrying more virulence genes had stronger pathogenicity to mice.[Conclusion] E. coli was identified as the pathogen causing pneumonia of foxes and raccoon dogs,and the number of virulence genes was related to the pathogenicity.

Key words:fox and raccoon dog pneumonia;Escherichia coli;drug resistance;virulence gene;pathogenicity