阴沟肠杆菌16S rRNA甲基化酶基因及氨基糖苷类修饰酶基因研究

目的 了解临床分离的40株阴沟肠杆菌中16S rRNA甲基化酶基因及氨基糖苷类修饰酶(AMEs)基因存在状况.方法 在2003年9月至2004年11月从解放军第98医院住院患者中分离40株阴沟肠杆菌,采用聚合酶链反应(PCR)及序列分析的方法分析5种16S rRNA甲基化酶基因(armA、rmtA、 rmtB、rmtC和rmtD)和9种AMEs基因[aac(3)-Ⅰ、aac(3)-Ⅱ、aac(3)-Ⅲ、aac(3)-Ⅳ、aac(6'')-Ⅰ b、aac(6'')-Ⅱ、ant(3'')-Ⅰ、ant(2'')-Ⅰ和aph(3'')-Ⅵ].结果 40株阴沟肠杆菌中,6种基因rmtB、aac(3)-Ⅱ、aac(6'')-Ⅰ b、ant(3'')-Ⅰ、ant(2'')-Ⅰ和aph(3'')-Ⅵ的阳性株数分别为5株(12.5%)、11株(27.5%)、29株(72.5%)、13株(32.5%)、2株(5.0%)和2株(5.0%);其余8种基因均阴性;AMEs基因总阳性率为85.0%(34/40).对29株aac(6'')-Ⅰ b基因PCR阳性产物进行测序,证实有7株(24.1%)单独携带aac(6'')-Ⅰ b-cr双功能酶基因(GenBank:EF375620、EU159121),18株(62.1%)单独携带aac(6'')-Ⅰ b-Snzhou(苏州型,EU085533),3株(10.3%)同时携带aac(6'')-Ⅰ b-Suzhou及aac(6'')-Ⅰ b-cr 2种亚型,仅1株(3.4%)为aac(6'')-Ⅰ b经典型.结论 临床分离的40株阴沟肠杆菌中16S rRNA甲基化酶基因阳性率较低而AMEs基因阳性率很高,至少存在5种AMEs基因.

Analysis on 16S rRNA methylase genes and aminoglycoside modifying enzymes genes in Enterobacter cloacae in China

OBJECTIVE: To investigate the 16S rRNA methylase genes and Aminoglycoside modifying enzymes (AMEs) genes in Enterobacter cloacae isolated from the People's Liberation Army 98th Hospital, Huzhou district, Zhejiang province, China. METHODS: 40 strains of Enterobacter cloacae were isolated from the inpatients between September, 2003 and November, 2004. 5 kinds of 16S rRNA methylase gene (including armA, rmtA, rmtB, rmtC and rmtD) and 9 kinds of AMEs gene [including aac (3)-I, aac(3)-II, aac(3)-III, aac(3)-IV, aac(6')-Ib, aac(6')-II, ant(3")-I, ant(2")-I and aph(3')-VI] were analyzed by PCR and verificated by DNA sequencing. RESULTS: In 40 strains of Enterobacter cloacae, the positive rates of genes of rmtB, aac(3)-II, aac(6')-I b, ant(3")-I, ant(2")-I and aph(3')-VI were 12.5% (5/40), 27.5% (11/40), 72.5% (29/40), 32.5% (13/40), 5.0% (2/40) and 5.0% (2/40), respectively. 8 kinds of the rest of genes were all tested negative. The total positive rate of AMEs gene was 85.0% (34/40). Among 29 strains of Enterobacter cloacae that the aac (6')-I b gene was positive, through PCR and verification by DNA sequencing, 7 strains (24.1%) were confirmed to take the aac(6')-I b-cr (the GenBank register number: EF375620, EU159121) alone, 18 strains (62.1%) were confirmed to take the aac(6')-I b-Suzhou (EU085533) alone, 3 strains (10.3%) were confirmed to take both aac(6')-I b-Suzhou and aac(6')-I b-cr while only 1 (3.4%) was aac(6')-I b (the classical type). CONCLUSION: There was lower positive rate of 16S rRNA methylase gene but very high AMEs genotypes in Enterobacter cloacae isolated from inpatients and the finding of rmtB gene was reported for the first time in the world. At least 5 kinds of AMEs gene existed in Enterobacter cloacae were isolated and they were the new host of both gene of aac(6')-I b- cr and aac(6')-I b-Suzhou, with aac(6')-I b-Suzhou gene was the predominance subtype in aac(6')-I b.