Susceptibility to Aminoglycosides and Distribution of aph and aac(3)-XI Genes among Corynebacterium striatum Clinical Isolates
Susceptibility to Aminoglycosides and Distribution of aph and aac(3)-XI Genes among Corynebacterium striatum Clinical Isolates
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DOI：
10.1371/journal.pone.0167856
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发表时间：
2016-12-09
期刊：
影响因子：
3.7
通讯作者：
Martinez-Martinez, Luis
中科院分区：
文献类型：
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作者：
Navas, Jesus;Fernandez-Martinez, Marta;Martinez-Martinez, Luis
纹状棒状杆菌是一种机会性病原体，通常具有多重耐药性，它与人类的严重感染有关。氨基糖苷类抗生素是用于治疗棒状杆菌感染的二线或补充抗生素。本实验室2005年至2009年分离的纹状棒杆菌对6种氨基糖苷类抗生素的敏感性及其耐药的分子机制进行了研究。药敏试验采用E-test法。采用聚合酶链式反应和测序技术对氨基糖苷类药物的耐药机制进行了研究。采用脉冲场凝胶电泳法对纹状体克隆扩散的可能性进行了研究。奈替米星和阿米卡星对纹状体分离株的MIC_(90)分别为0.38和0.5 mg/L。菌株中有27株对卡那霉素的MIC90值为256 mg/L，其中26株对aph(3‘)-IC基因呈阳性。我们的纹状体中有36例对链霉素耐药，其中23例同时携带aph(3‘’)-Ib和aph(6)-ID基因。在44株菌株中发现了编码新的氨基糖苷类3-N乙酰转移酶的基因aac(3)-XI，它们对庆大霉素和妥布霉素的MIC值均为1 mg/L。CS4933是一株对卡那霉素和链霉素敏感性极低的纹状体菌株，它含有一个氨基糖苷类抗药性区域，其中包括aph(3‘)-IC基因，以及aph(3’‘)-Ib和aph(6)-ID基因串联。从分离的纹状体菌株中鉴定出46种主要的pFGE类型，表明它们主要不是克隆的。我们的结果表明，临床纹状体对氨基糖苷类抗生素高度耐药，且大多无关。
Corynebacterium striatum is an opportunistic pathogen, often multidrug-resistant, which has been associated with serious infections in humans. Aminoglycosides are second-line or complementary antibiotics used for the treatment of Corynebacterium infections. We investigated the susceptibility to six aminoglycosides and the molecular mechanisms involved in aminoglycoside resistance in a collection of 64 Corynebacterium striatum isolated in our laboratory during the period 2005-2009. Antimicrobial susceptibility was determined using E-test. The mechanisms of aminoglycoside resistance were investigated by PCR and sequencing. The 64 C. striatum were assessed for the possibility of clonal spreading by Pulsed-field Gel Electrophoresis (PFGE). Netilmicin and amikacin were active against the 64 C. striatum isolates (MICs90 = 0.38 and 0.5 mg/L, respectively). Twenty-seven of the 64 C. striatum strains showed a MIC90 for kanamycin > 256 mg/L, and 26 out the 27 were positive for the aph(3')-Ic gene. Thirty-six out of our 64 C. striatum were streptomycin resistant, and 23 out of the 36 carried both the aph(3 '')-Ib and aph(6)-Id genes. The gene aac(3)-XI encoding a new aminoglycoside 3-N acetyl transferase from C. striatum was present in 44 out of the 64 isolates, all of them showing MICs of gentamicin and tobramycin > 1 mg/L. CS4933, a C. striatum showing very low susceptibility to kanamycin and streptomycin, contains an aminoglycoside resistance region that includes the aph(3')-Ic gene, and the tandem of genes aph(3 '')-Ib and aph(6)-Id. Forty-six major PFGE types were identified among the 64 C. striatum isolates, indicating that they were mainly not clonal. Our results showed that the 64 clinical C. striatum were highly resistant to aminoglycosides and mostly unrelated.