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首页> 外文期刊>Journal of Molecular Biology Research >Small Colony Variants and Triclosan Resistance in Five International Clones of Methicillin Resistant Staphylococcus aureus
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Small Colony Variants and Triclosan Resistance in Five International Clones of Methicillin Resistant Staphylococcus aureus

机译：耐甲氧西林金黄色葡萄球菌的五个国际克隆中的小菌落变异和三氯生抗性

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Triclosan (2.4.4’ trichloro-2’-hydroxydiphenyl ether) is a broad-spectrum biocide which is also used to decolonise patients with methicillin resistant Staphylococcus aureus (MRSA). Microbial resistance to biocides has recently been reported, so it is important that new products should be tested for resistance that may arise from continued exposure to such agents. In a previous study 232 strains of MRSA isolated during 1997-2000 in 30 Scottish hospitals were tested for triclosan susceptibility; overall the minimum inhibitory concentrations (MIC) of triclosan for these strains ranged from <=0.015 to 4 mg/L. In the present study, resistance to triclosan was examined in five major international MRSA clones [Clonal Complex (CC22, CC30, CC45, CC8 and CC5)] by growing them in brain heart infusion broth in the presence of increasing concentrations of triclosan (0.03mg/L, 0.06 mg/L, 0.125 mg/L, 0.25 mg/L, and 0.5 mg/L ) for up to 67 days. Different MRSA clones showed different degrees of triclosan tolerance. CC22 (EMRSA–15), CC30 (EMRSA-16) and CC5 triclosan-tolerant derivatives showed a significant increase in triclosan MIC when compared to their parents, principally through the appearance of pinpoint-size small colony variants (SCV), as well as colonies of normal or small size. These MRSA SCVs emerged in different clones and at different times of exposure to triclosan. The triclosan MICs of mutants of all colony sizes rose to 4 mg/L in all clones except MRSA111-29 (CC45) which had an MIC 4-8 mg/L. Triclosan-resistant MRSA strains were also able to grow in the presence of higher triclosan concentrations: 1.25 mg/L (CC22), 10 mg/L (CC30), 25 mg/L (CC45), 5 mg/L (CC8) and 25 mg/L (CC5). In addition, six triclosan resistant derivatives from each MRSA clone, together with their parental clone, were examined by antibiogram, polymerase chain reaction (PCR) ribotyping and detailed susceptibility to triclosan in terms of MIC and kill kinetics. Susceptibility to the aminoglycosides kanamycin, neomycin and tobramycin was decreased in four clones, and tetracycline susceptibility increased in one clone. PCR ribotyping confirmed clonally similar to the mutants. Kill kinetics of both parents and their triclosan resistant mutants showed 5-Logs reduction at 0.5 min and 5 min respectively in all five clones. In conclusion, repeated exposure of MRSA to triclosan may result in resistance to this biocide, and to clinically-relevant antimicrobials.
机译：三氯生（2.4.4'三氯-2'-羟基二苯醚）是一种广谱杀菌剂，也可用于对耐甲氧西林金黄色葡萄球菌（MRSA）的患者进行非殖民化治疗。最近已报道了微生物对杀生物剂的抗药性，因此重要的是应测试新产品的抗药性，所述抗药性可能是由于持续接触此类药剂而引起的。在一项先前的研究中，对1997年至2000年在苏格兰30家医院中分离出的232株MRSA进行了三氯生敏感性测试。总体上，这些菌株的三氯生最低抑菌浓度（MIC）为<= 0.015至4 mg / L。在本研究中，通过在浓度不断增加的三氯生（0.03mg /L、0.06 mg / L，0.125 mg / L，0.25 mg / L和0.5 mg / L），最多可使用67天。不同的MRSA克隆显示出不同程度的三氯生耐受性。与它们的亲本相比，CC22（EMRSA-15），CC30（EMRSA-16）和CC5三氯生耐受性衍生物显示三氯生MIC显着增加，主要是通过出现精确大小的小菌落变体（SCV）以及正常或较小大小的菌落。这些MRSA SCV出现在不同的克隆中以及暴露于三氯生的不同时间。除MRSA111-29（CC45）MIC为4-8 mg / L的所有克隆外，所有菌落大小的突变体的三氯生MIC均上升至4 mg / L。具有三氯生抗性的MRSA菌株也能够在较高的三氯生浓度下生长：1.25 mg / L（CC22），10 mg / L（CC30），25 mg / L（CC45），5 mg / L（CC8）和25 mg / L（CC5）。此外，通过抗菌素谱分析，聚合酶链反应（PCR）核糖分型法检查了每个MRSA克隆及其亲本克隆的六种对三氯生具有抗性的衍生物，并根据MIC和杀灭动力学对三氯生进行了详细的敏感性研究。在四个克隆中，对氨基糖苷类卡那霉素，新霉素和妥布霉素的敏感性降低，而在一个克隆中，四环素的敏感性增加。 PCR核糖分型证实了克隆突变体相似。亲本及其三氯生抗性突变体的杀伤动力学在所有五个克隆中分别在0.5分钟和5分钟时降低了5-Logs。总之，将MRSA反复暴露于三氯生可能会导致对该杀生物剂以及与临床相关的抗药性产生耐药性。

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