Institute of Antibiotics, Huashan Hospital, Fudan University, 12 M. Wulumuqi Road, 200040, Shanghai, China.
Eur J Clin Microbiol Infect Dis. 2010 Nov;29(11):1349-53. doi: 10.1007/s10096-010-1004-1. Epub 2010 Jul 8.
16S rRNA methylases confer high-level resistance to most aminoglycosides in Gram-negative bacteria. Seven 16S rRNA methylase genes, armA, rmtA, rmtB, rmtC, rmtD, rmtE and npmA, have been identified since 2003. We studied the distribution of methylase genes in more than 200 aminoglycoside-resistant Gram-negative clinical isolates collected in 2007 at our hospital in Shanghai, China. 16S rRNA methylase genes were amplified by polymerase chain reaction (PCR) among 217 consecutive clinical isolates of Gram-negative bacilli resistant to gentamicin and amikacin by a disk diffusion method. 16S rRNA methylase genes were present in 97.5% (193/198) of clinical isolates highly resistant to amikacin (≥512 μg/ml), with armA and rmtB detected in 67.2 and 30.3% of strains, respectively, while no 16S rRNA methylase genes were detected in 19 strains with amikacin minimum inhibitory concentration (MIC) ≤256 μg/ml. armA or rmtB genes were detected in 100% of 104 strains of Enterobacteriaceae, and these two genes were equally represented (49 vs. 55 strains). Genes for armA or rmtB were detected in 94.7% (89/94) of Acinetobacter baumannii and Pseudomonas aeruginosa strains, and armA was predominant (84 vs. 5 strains with rmtB). No rmtA, rmtC, rmtD or npmA genes were found. Enterobacterial repetitive intergenic consensus sequence (ERIC-PCR) indicated that armA and rmtB genes were spread by both horizontal transfer and clonal dissemination.
16S rRNA 甲基化酶使革兰氏阴性菌对大多数氨基糖苷类药物具有高水平的耐药性。自 2003 年以来，已经鉴定出了 7 种 16S rRNA 甲基化酶基因，包括 armA、rmtA、rmtB、rmtC、rmtD、rmtE 和 npmA。我们研究了 2007 年在中国上海我院收集的 200 多株氨基糖苷类耐药革兰氏阴性临床分离株中甲基化酶基因的分布。通过纸片扩散法对 217 株连续临床分离的耐庆大霉素和阿米卡星的革兰氏阴性杆菌进行了聚合酶链反应（PCR）扩增 16S rRNA 甲基化酶基因。在对阿米卡星（≥512μg/ml）高度耐药的 198 例临床分离株中，有 97.5%（193/198）携带 16S rRNA 甲基化酶基因，其中 armA 和 rmtB 分别在 67.2%和 30.3%的菌株中检出，而在 19 株阿米卡星最低抑菌浓度（MIC）≤256μg/ml 的菌株中未检出 16S rRNA 甲基化酶基因。在 104 株肠杆菌科菌株中，armA 或 rmtB 基因的检出率为 100%，这两种基因的检出率相同（49 株与 55 株）。在 94.7%（89/94）的鲍曼不动杆菌和铜绿假单胞菌菌株中检出 armA 或 rmtB 基因，且以 armA 为主（84 株与 5 株 rmtB）。未检出 rmtA、rmtC、rmtD 或 npmA 基因。肠杆菌基因重复序列间共有 consensus 序列（ERIC-PCR）表明，armA 和 rmtB 基因通过水平转移和克隆传播而传播。
