中文摘要：

本研究旨在检测并对比分析中国北方地区3个荷斯坦牛场乳源金黄色葡萄球菌（Staphylococcus aureus,简称金葡菌）的流行情况及乳汁中总菌群的抗生素耐药性。试验采集北方地区3个荷斯坦牛场的生产群奶样、大罐奶样和临床型乳房炎牛奶样共181份,首先采用Baird-Parker选择性培养基对金葡菌进行分离纯化;再采用特异性PCR方法鉴定含金葡菌特异基因nuc的金葡菌菌株;最后采用琼脂稀释法检测奶样中总菌群及金葡菌对14种抗生素的耐药性。结果发现,181份奶样带菌率为100%;金黄色葡萄球菌检出率为16.03%,分离纯化了48株金葡菌。奶样总菌群耐药性检测结果表明,中国北方地区3个荷斯坦牛场对于β-内酰胺类抗生素（苯唑西林、氨苄西林、头孢西丁、头孢哌酮）耐药性均较高,达89%以上;对红霉素、利福平、四环素、万古霉素、甲氧苄啶/磺胺甲噁唑、阿莫西林/克拉维酸的耐药性达80%以上;对氯霉素的耐药率过半;仅对阿米卡星耐药率较低（18%~58%）。对金葡菌耐药性检测结果显示,3个牛场金葡菌对环丙沙星、头孢西丁和甲氧苄啶/磺胺甲噁唑有较高耐药性,但均对阿米卡星、氯霉素、加替沙星和万古霉素敏感。3个牛场绝大多数菌株都产生了多重耐药谱。研究结果为奶牛场乳源总菌群、金葡菌耐药性情况及科学用药提供试验数据。

英文摘要：

The aim of the study was to investigate and compare the prevalence and antimicrobial resistance profiles of Staphylococcus aureus（S.aureus）and total coliforms isolated from cow milk at three Chinese Holstein herds in northern China region.A total of 181 milk samples including productive group,milk from tank and mastitis of three dairy farms were collected and screened for the presence of S.aureusincubated onto Baird-Parker agar.S.aureusislolates were characterized using PCR for its unique nuc gene.Agar dilution method was used for the detection of antimicrobial profiles of S.aureus and the milk samples.Of the 181 milk samples,100% were contaminated with the microorganisms,16.03% were positive for S.aureus（n=48）.For the total coliforms,the resistance was most frequently observed to the beta-lactam antibiotic（oxacillin,ampicillin,cefoxitin,cefoperazone）,which was above 89%;followed by erythrocin,rifampicin,tetracycline,vancomycin,trimethoprim,amoxycillin/clavulanate potassium with above 80%;chloramphenicol（above 50%）;the least was amikacin（18%to 58%）.The antimicrobial resistance profiles of S.aureus in three herds indicated that a high degree of resistance was observed for ciprofloxacin,cefoxitin and trimethoprim;while they were sensitive to amikacin,chloramphenicol,gatifloxacin and vancomycin.The majority of the isolates were multidrug resistance.The results laid a foundation for improving the udder health and treating the mastitis scientifically.