This study was undertaken to investigate the resistance phenotypes to macrolide-lincosamide-streptogramin B (MLS_B) antibiotics and their associated genotypes in isolates of Staphylococcus aureus. We analyzed one hundred, consecutive, non-duplicate isolates (methicillin-susceptible MSSA, n = 53 and methicillin-resistant MRSA, n = 47) obtained from various clinical samples between July 2012 to December 2013. The resistance profile to MLS_B antibiotics was determined by phenotypic methods and the resistance genes were detected by PCR assays. All of the isolates were subjected to pulsed-field gel electrophoresis (SmaI-PFGE). The overall prevalence of resistance to MLS_B antibiotics was 38% and the resistance phenotype distribution was as follows: cMLS_B, 22%; iMLS_B, 10%; MS_B, 5% and L, 1%. We detected ermA, ermC, ermB and mrsA/B genes in these resistant isolates. The single ermA gene was commonly observed mainly in those with a cMLS_B R phenotype, whereas the combination ermA and ermC was more commonly observed in isolates with inducible expression. The patterns of SmaI-PFGE suggest a great genetic diversity in both MRSA and MSSA resistant to MLS_B antibiotics. The results demonstrate the local presence of S. aureus resistant to MLS_B antibiotics and its most frequently described responsible genes. Some of these isolates, especially those with the iMLS_B phenotype, may be associated with therapeutic failure. Therefore, efforts should be directed to the correct detection of all MLS_B resistant isolates using appropriate laboratory tests. PFGE results reveal a wide spread of resistance genes rather than the circulation of S. aureus clones resistant to MLS_B antibiotics.

本研究旨在调查金黄色葡萄球菌分离株对大环内酯-林可酰胺-链霉素 B (MLS _B ) 抗生素的耐药表型及其相关基因型。我们分析了 2012 年 7 月至 2013 年 12 月期间从各种临床样本中获得的 100 个连续的非重复分离株（甲氧西林敏感的 MSSA，n = 53 和耐甲氧西林的 MRSA，n = 47）。对 MLS _B抗生素的耐药谱为通过表型方法确定，通过PCR测定法检测抗性基因。所有分离株均进行脉冲场凝胶电泳（Sma I-PFGE）。_{对 MLS B}的总体耐药率抗生素为38%，耐药表型分布如下：cMLS _B，22%；iMLS _B , 10%; MS _B，5% 和 L，1%。我们在这些耐药菌株中检测到ermA、ermC、ermB和mrsA/B基因。单一ermA基因主要在具有 cMLS _B R 表型的那些中观察到，而ermA和ermC组合在具有诱导表达的分离物中更常见。Sma I-PFGE的模式表明 MRSA 和 MSSA 对 MLS _{B具有很大的遗传多样性}抗生素。结果表明，局部存在对 MLS _B抗生素及其最常描述的负责基因具有抗性的金黄色葡萄球菌。其中一些分离株，尤其是具有 iMLS _B表型的分离株，可能与治疗失败有关。因此，应努力使用适当的实验室测试正确检测所有 MLS _B抗性分离株。PFGE 结果揭示了耐药基因的广泛传播，而不是对 MLS _B抗生素耐药的金黄色葡萄球菌克隆的循环。