乳源凝固酶阴性葡萄球菌的PFGE分型及耐药性研究

Antimicrobial Resistance and PFGE Profiles of Coagulase-negative Staphylococci Isolated from Subclinical Mastitis Milk

对分离自隐性乳房炎乳样中的25株凝固酶阴性葡萄球菌（CNS）进行脉冲场凝胶电泳（PFGE）分型，结果表明不同牛场流行的CNS种类和基因型有所不同，即使来自同一牛场的相同菌种也表现出完全不同的流行克隆型．证明了菌种基因型的多样性。MIC测定结果显示所有菌株都表现出三重以上耐药，且耐药程度高（36％～96％）。携带最多的耐药基因是ermC（96．55％）和tetK（89．66％）基因，然后是ermB（82．76％），tetM（82．76％），msrA（86．21％），msrB（82．76％）和lnuA（72．41％）基因，mph的基因含量最少，为41.38％。另外，本文还检测出4株恍cA基因阳性菌株，即超级耐药菌-MRCNS.MTP和刚果红试验结果显示88％的菌株都具有产生物被膜的能力。并且其多重耐药性显著高于不产生物被膜的菌株。综上所述，目前，乳源及食品动物源细菌耐药形式极其严峻，多重耐药菌及耐药基因的传播，给食品安全及公众健康造成了巨大风险，急需出台一系列的用药规定,加大科研力度，研究安全、绿色、高效新药物。

25 coagulase-negative staphylococci （CNS） were isolated from subclinical mastitis milk, and typed by pulsed-field gel electrophoresis （PFGE）. The results showed that the predominant CNS species and PFGE types were dairy farms specificity. Although the same CNS species isolates from one farms exhibited completely different genotype clones, which showed the species diversity. Minimum inhibitory concentration （MIC） determination results showed that all the isolates were resistant to two or more antibiotics, and exhibited a high antimierobial resistance（36%-96%）. Among of the 11 antimierobial resistance genes, the most detected genes were ermC （96.55%） and tetK （89.66%）, followed by ermB （82.76%）, tetM（82.76%）,msrA（86.21%）,msrB（82.76%） and lnuA（72.41%） genes, and mph was least detected genes （41.38%）. It was noted that 4 methieillin resistant CNS was identified by PCR for mecA gene in this study. Additional- ly, by MTP and CRA methods, 88% of isolates were determined to have biofilm producing ability. Compared to the biofilm-producing negative strains, the positive ones were proved to be more frequent multiple resistant. In conclusion, nowadays, antimicrobial resistance of isolates from milk and food animals were very serious. The transmission of multiple drug resistance（MDR） bacteria and related genes would caused a huge risk to food safety and public health. Bull antibi- otic restrictions policy and programs should be promoted, and more researches about the development of safe, green and effective drugs were necessary.