Fan Qin, Liu Shu-liang, Han Xin-feng, Hou Xiao-gang, Yan Qi-gui
To analyze the contamination situation and drug resistance of Staphylococcus aureus(Sa) in the dairy production chain,523 samples of dairy food(raw milk,semi-finished milk,milk products) were collected.With reference to GB 4789.10-2010 and PCR,the isolation and identification of Sa were carried out using broth dilution method to determine the antimicrobial susceptibility to 12 antibiotics of Sa isolates.Multiplex PCR was used to analyze the relationship between the resistance to beta-lactams and the antimicrobial resistance genes(mecA,blaZ).The Results indicated that the total detectable rate of Sa was 24.9%(129 samples),in which,the positive rate in raw milk,semi-finished milk and milk products were 37.5%,7.1% and 0.0% respectively.All the isolates were mostly resistant to penicillin(97.7%),followed by resistance to ampicillin(95.4%),trimethoprim/sulfamethoxazole(61.9%),amoxicillin/clavulanic acid(61.7%),erythromycin(39.7%),tetracycline(36.6%),clindamycin(35.2%).All strains were susceptible to oxacillin,ceftiofur,florfenicol.69.8% of the isolates were multi-drug resistant,the whole test strains were multi-drug resistant mainly to penicillins,sulfonamides,macrocyclic lipids,lincosamides and tetracyclines.The positive rates for detection of nuc and blaZ genes by PCR were 100.0%,60.5% and 0.0% respectively.There were a lot Correspondence between the resistance to beta-lactams and the detection rate of the resistance gene(blaZ) about Sa from different segments of dairy production chain.The contamination and drug resistance of Sa isolates recovered from dairy production chain were not optimistic,so we must take it seriously and avoid the occurrence of food-borne illness.
