Isolation and Identification of Staphylococcus chromogenes from Yak Milk and Analysis of Virulence and Drug Resistance
[Objective]The aim of this study was to investigate the drug resistance of Staphylococcus chromogenes derived from yak milk in Lhasa and Nagqu,Tibet,and explore the carriage of virulence and drug resistance genes.[Method]Staphylococcus chromogenes was isolated and cultured from yak milk,and its biochemical characteristics were analyzed.Molecular biological identification was performed by PCR and virulence genes and drug resistance genes carried by the isolates were detected.The drug sensitivity test was carried out by Kirby-Baue(K-B)method.[Result]11 strains of Staphylococcus chromo genes were isolated and identified from 66 yak milk,and the isolation rate was 16.67％.On 5％defibrated sheep blood agar medium,the isolates formed milky white colonies with neat edges,round,smooth and opaque,without hemolysis.Gram staining microscopy showed positive cocci in a moniliform arrangement.Biochemical identification showed that the isolates could ferment fructose,lactose,mannose and sucrose,and the nitrate reduction reaction was positive.The results of 16S rRNA amplification sequencing showed that the similarity between the isolates and Staphylococcus chromogenes in GenBank was more than 98％.2 biofilm-related regulatory genes,icaA and bap,were detected among 13 virulence genes,and the detection rates were 81.82％.Among the 14 drug resistance genes,the detection rate of aminoglycoside resistance gene aph(3')-Ⅰ a,macrolide resistance gene ermB and sulfonamine resistance gene sul1 was 63.64％,27.27％and 9.09％,respectively.The resistance rates to penicillin,ampicillin and tetracycline was 100.00％,63.64％and 36.36％,respectively.[Conclusion]In this study,11 strains of Staphylococcus chromogenes were isolated from 66 yak milk samples collected from Lhasa and Nagqu.The isolates had different degrees of resistance to penicillin,ampicillin,tetracycline and other common antimicrobials,and carried fewer types of virulence and resistance genes.The results provided a theoretical basis for the prevention and treatment of Staphylococcus chromo genes in yaks.
yak milkStaphylococcus chromogensisolation and identificationvirulence genesdrug resistance genes
万方数据
维普
