发现1株产NDM-1型碳青霉烯酶非脱羧勒克菌

Finding of a NDM-1 carbapenems-producing Leclercia adcarboxglata

目的探讨1株碳青霉烯类耐药非脱羧勒克菌的耐药机制。方法采用全自动微生物分析仪、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)技术及16S r RNA序列分析进行菌种鉴定;采用全自动微生物分析仪进行常规药物敏感性试验,用E-test条检测菌株对亚胺培南的最低抑菌浓度(MIC);改良碳青霉烯酶灭活试验(m CIM法)检测碳青霉烯酶表型;聚合酶链反应(PCR)及测序确定耐药基因型;采用接合试验、S1酶切脉冲场凝胶电泳(S1-PFGE)方法分析其携带质粒的特征。结果临床分离非脱羧勒克菌菌株对亚胺培南、除氨曲南外的其他β内酰胺类抗菌药物及氨基糖苷类耐药,对喹诺酮类和磺胺类药物敏感;接合试验使受体菌E.coli J53获得与非脱羧勒克菌相似的耐药谱。碳青霉烯酶表型试验阳性,PCR扩增及测序表明该菌株同时携带blaNDM-1、blaTEM和aac(6')-Ib,而接合子仅携带blaNDM-1;S1-PFGE示非脱羧勒克菌具有3个质粒。结论非脱羧勒克菌对碳青霉烯类药物耐药为携带blaNDM-1基因造成,该基因可能存在于100 kb左右的可接合传递的质粒上。

Objective：To investigate the resistance mechanism of a carbapenems-resistant Leclercia adcarboxglata. Methods： The species was identified by the automatic microbial analyzer, matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF MS） and 16S rRNA sequence analysis. The conventional drug susceptibility test was detected with automatic microbial analyzer, and the minimum inhibitory concentration （MIC） for imipenem was examined by E-test. The phenotypes of carbapenemase were detected by modified carbapenem inactivation method （mCIM） and the genotypes of resistance genes were detected by polymerase chain reaction （PCR） and DNA sequencing. The characteristics of the carried plasmid were analyzed by conjugation test and S1-pulsed-field gel electrophoresis （S1-PFGE）. Results：The clinical isolates of Leclercia adcarboxglata were resistant to imipenem, other beta-lactam antibiotics（except aztreonam） and aminoglycosides, but sensitive to quinolones and sulfonamides. The conjugation test resulted in a drug resistance spectrum of the receptor strain E.coli 53 similar to Leclercia adcarboxglata bacteria. The phenotype of carbapenemase was positive. PCR amplification and sequencing analysis showed that blaNDM-1, blaTEM and aac （6′） - Ib were detectable in the isolates simultaneously, while the conjugon only carried blaNDM-1. S1-PFGE revealed that Leclercia adcarboxglata carried 3 plasmids. Conclusion：The carbapenems resistance of Leclercia adcarboxglata may contribute to carrying blaNDM-1 gene which may exist in an around 100 kb plasmid transmitted with conjugation.