Isolation,Identification and Biological Characteristics Analysis of a Strain of Haemophilus parasuis Serotype 10
[Objective]This study was aimed to elucidate the physiological and biochemical characteristics,virulence and drug sensitivity of the pathogen causing Haemophilus parasuis disease in piglets from a pig factory in Jingzhou,China,so as to provide scientific basis for the prevention and treatment of this disease in the future.[Method]The pathogenic bacteria were isolated from infected piglets and identified by morphological observation,physiological and biochemical identification,PCR identification,16S rRNA gene sequencing,serotype identification and multi-sequence site typing(MLST).The pathogenicity and drug resistance of the isolate were analyzed by virulence gene detection,pathogenicity test of mouse,drug sensitivity test and traditional Chinese medicine treatment.[Result]Through morphological observation,physiological and biochemical experiments,16S rRNA sequence alignment and phylogenetic tree analysis,the isolate was identified as Haemophilus parasuis.Serotype and MLST analysis confirmed that the isolate was serotype 10 and ST-299.Virulence gene test showed that the isolate had 15 virulence genes such as CapD,vta1 and vta2.The isolate could cause obvious lesions in many organs of the infected mice by intraperitoneal injection and had strong pathogenicity.The detection of drug resistance genes showed that the isolate had β-lactam resistance gene blaOXA and fluoroquinolone resistance gene gyrA.The drug sensitivity test showed that the isolate was sensitive to 10 kinds of antibiotics,such as ceftriaxone,neomycin and minocycline,and to 3 kinds of traditional Chinese medicines including realgar,Tussilago farfara and Buthus martensii.The traditional Chinese medicine treatment showed that realgar and Buthus martensii had obvious therapeutic effect on mice infected by the isolate.[Conclusion]In this study,a strain of Haemophilus parasuis serotype 10 was successfully isolated which could cause bleeding and necrosis of multiple organs in infected mice,and was sensitive to 10 kinds of antibiotics and 3 kinds of traditional Chinese medicines.It was found that realgar and Buthus martensii were effective in treating mice infected by the isolate.The results provided a reference for future prevention and treatment of Haemophilus parasuis.
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