Epidemiological Investigation And Antimicrobial Resistance Of Staphylococcus And Streptococcus From Dairy Cow In The Inner Mongolia

Cow mastitis is one of the most common diseases of dairy cattle,resulting in enormous economic losses to the industry.Pathogen infection is the main cause of cow mastitis.To investigate the incidence of mastitis and the prevalence of major pathogens in different regions of Inner Mongolia,330 samples collected from three large-scale dairy farms were isolated and identified in different areas of Inner Mongolia.A total of 174 Staphylococcus and 24 Streptococcus were obtained,and the isolation rates were 52.73%(174/330)and 7.27%(24/330),respectively.2 types of Staphylococcus and 3 types of Streptococcus were subjected to examination of DNA fingerprint.34 different patterns of Staphylococcus were obtained from 51 Staphylococcus species including 8 S.aureus and 16 S.chromogenes,16 Streptococcus.sp including 10 S.agalactiae,3 S.dysgalactiae and 3 S.uberis.The isolates of S.aureus were further characterized by Multilocus Sequence Typing(MLST).The results of PFGE typing were consistent with that of the MLST typing.In this study,all clinical isolates were subjected for determination of antimicrobial resistance pattern and resistant determinants,using broth microdilution and PCR methods,repectively.Of the S.aureus isolates examined in this study,were resistant to lincomycin(50%),penicillin(62.5%)and oxacillin(50%).It should be noted that all isolates were susceptible to vancomycin,tiamulin,valnemulin and florfenicol.16 Streptococci resistance rate is more serious to lincomycin and erythromycin,but the rate of resistance to ?-lactams is relatively low.In this study,it was found that the antibiotic-resistant genes related to ?-lactam antibiotics,mainly bla Z gene.Lincomycin,macrolide and tetracycline antibiotics resistance genes are mainly mediated by lnu(A),lnu(B),erm(B),tet(M),tet(O),tet(L)respectively.Three isolates of S.uberis carrying multiple resistant gene lsa(E)were found in this study.Results of screening for resistance gene showed that three S.uberis isolates carried lsa(E)gene.Further research showed that the lsa(E)gene was located in its chromosoal through filter matting,electroporation and Southern blotting assay.