新疆部分地区生乳中金黄色葡萄球菌的分离鉴定及耐药性分析

Isolation,Identification and Drug Resistance Analysis of Staphylococcus aureus in Raw Milk in Some Areas of Xinjiang

【目的】探明新疆部分地区生乳中金黄色葡萄球菌流行情况及耐药性,为该地区生乳中金黄色葡萄球菌的监测及保障生乳质量安全提供理论依据。【方法】试验随机从南北疆规模化奶牛场采集110份生乳样品。采用增菌培养、分离纯化、革兰氏染色、生化鉴定及PCR法对奶样中金黄色葡萄球菌进行分离鉴定,并利用微量肉汤稀释法及PCR方法对金黄色葡萄球菌进行16种抗菌药物的耐药表型及耐药基因分析。【结果】从110份奶样中分离出18株金黄色葡萄球菌,分离株呈浅黄色、光滑凸起的圆形菌落,革兰氏染色镜检呈紫色、短链状排列的革兰氏阳性菌,生化试验结果符合金黄色葡萄球菌生化特点,经16S rDNA及nuc基因PCR扩增鉴定为金黄色葡萄球菌,分离率为16.36%(18/110)。药敏试验结果显示,金黄色葡萄球菌分离株对氨苄西林、青霉素及磺胺异噁唑具有较高的耐药性,耐药率分别为100%、83.33%和77.78%,而对万古霉素、复方新诺明、苯唑西林、头孢噻吩、头孢噻呋、利福昔明及环丙沙星7种抗菌药物高度敏感,敏感率分别为100%、100%、94.44%、94.44%、94.44%、94.44%和94.44%。其中有14株金黄色葡萄球菌为多重耐药菌,多重耐药率为77.78%。耐药基因检测结果显示,大环内酯类耐药基因ermB检出率最高,为50.00%,其次为β-内酰胺类耐药基因mecA,检出率为27.28%,磺胺类耐药基因Sul 1的检出率为22.22%。【结论】新疆奶牛场生乳中分离的金黄色葡萄球菌的流行及耐药情况仍较严重,且存在多重耐药现象,因此,对生乳中金黄色葡萄球菌耐药性的监测有重要意义。

【Objective】The purpose of the experiment was to investigate the prevalence and drug resistance of Staphylococcus aureus in raw milk in some areas of Xinjiang,and provide a theoretical basis for monitoring Staphylococcus aureus in raw milk in this area and ensure the quality and safety of raw milk.【Method】A total of 110 raw milk samples were randomly collected from large-scale dairy farms in Northern and Southern Xinjiang.Staphylococcus aureus was isolated and identified from milk samples by enrichment culture,isolation and purification,Gram staining,biochemical identification and PCR.The phenotypic resistance and drug resistance genes of Staphylococcus aureus to 16 antimicrobial agents were analyzed by broth microdilution and PCR.【Result】18 strains of Staphylococcus aureus were isolated from 110 milk samples.The isolated strains showed light yellow,smooth and convex round colonies.Gram staining microscopy showed purple,short chain arrangement of Gram-positive bacteria.The biochemical test results conformed to the biochemical characteristics of Staphylococcus aureus.The isolated strains were identified as Staphylococcus aureus by 16S rDNA and nuc gene PCR amplification,with a separation rate of 16.36%(18/110).Drug susceptibility results showed that Staphylococcus aureus isolates had high resistance rates to ampicillin,penicillin and sulfaisoxazole,with resistance rates of 100%,83.33%and 77.78%respectively,while they were highly sensitive to vancomycin,compound minophen,oxacillin,cefalotin,ceftiofur,rifaximin and ciprofloxacin,with sensitivity rates of 100%,100%,94.44%,94.44%,94.44%,94.44%and 94.44%,respectively.Among them,14 strains of Staphylococcus aureus were multidrug resistant,and the multidrug resistance rate was 77.78%.The detection results of drug resistance genes showed that the detection rate of macrolide resistance gene ermB(50.00%)was the highest,followed byβ-lactam resistance gene mecA(27.28%)and Sul 1(22.22%).【Conclusion】The prevalence and drug resistance rate of Staphylococcus aureus isolated from raw milk obtained from dairy farms in Xinjiang were still relatively serious,and the phenomenon of multi-drug resistance existed,which emphasized the importance of monitoring the drug resistance of Staphylococcus aureus in raw milk.