Liu Yali, Xu Heping, Xu Zhipeng, Kudinha Timothy, Fan Xin, Xiao Meng, Kong Fanrong, Sun Hongli, Xu Yingchun
1 Department of Clinical Laboratory, Peking Union Medical College Hospital, Peking Union Medical College , Chinese Academy of Medical Sciences, Beijing, China .
2 Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University , Xiamen, China .
Microb Drug Resist. 2015 Oct;21(5):507-11. doi: 10.1089/mdr.2014.0217. Epub 2015 Apr 29.
Previous studies indicate that macrolide resistance in Moraxella catarrhalis isolates is less common in adults than in children. However, few studies have investigated M. catarrhalis macrolide resistance mechanisms in adult patients. In this study, 124 M. catarrhalis isolates were collected from adult patients in a Chinese tertiary hospital, between 2010 and 2013, and investigated for antimicrobial resistance. We found that only seven isolates were macrolide resistant and all exhibited high-level macrolide resistance (minimum inhibitory concentrations >256 μg/ml). Multilocus sequence typing (MLST) suggested that M. catarrhalis has a diverse population; in particular, both pulsed-field gel electrophoresis and MLST revealed that all the seven high-level macrolide-resistant M. catarrhalis belonged to different clones. A 934-bp 23S rRNA gene sequencing showed that only nine isolates (including all the seven macrolide-resistant isolates) had mutations within the studied region, and only the seven macrolide-resistant isolates had mutation of A2330T. No other known macrolide-resistance determinant genes (ermA, ermB, mefA, or mefE) were detected. These findings support previous studies in children on M. catarrhalis macrolide-resistant isolates and suggest that the 23S rRNA gene A2330T mutation is responsible for the high M. catarrhalis macrolide resistance. The findings prompted us to successfully develop a simple allele-specific polymerase chain reaction assay for high-level macrolide-resistant 23S rRNA gene A2330T mutation for future clinical and further surveillance use.
先前的研究表明，卡他莫拉菌分离株对大环内酯类药物的耐药性在成人中比在儿童中少见。然而，很少有研究调查成人患者中卡他莫拉菌对大环内酯类药物的耐药机制。在本研究中，于2010年至2013年间从一家中国三级医院的成年患者中收集了124株卡他莫拉菌分离株，并对其进行了抗菌药物耐药性调查。我们发现只有7株分离株对大环内酯类药物耐药，且均表现出高水平的大环内酯类药物耐药性（最低抑菌浓度>256μg/ml）。多位点序列分型（MLST）表明卡他莫拉菌具有多样化的菌群；特别是，脉冲场凝胶电泳和MLST均显示，所有7株高水平大环内酯类药物耐药的卡他莫拉菌都属于不同的克隆。一段934bp的23S rRNA基因测序显示，只有9株分离株（包括所有7株大环内酯类药物耐药分离株）在研究区域内有突变，且只有7株大环内酯类药物耐药分离株有A2330T突变。未检测到其他已知的大环内酯类药物耐药决定基因（ermA、ermB、mefA或mefE）。这些发现支持了先前关于儿童卡他莫拉菌大环内酯类药物耐药分离株的研究，并表明23S rRNA基因A2330T突变是卡他莫拉菌高水平大环内酯类药物耐药的原因。这些发现促使我们成功开发了一种简单的等位基因特异性聚合酶链反应检测方法，用于检测高水平大环内酯类药物耐药的23S rRNA基因A2330T突变，以供未来临床和进一步监测使用。
