Distribution and molecular characterization of tetracycline resistance in Laribacter hongkongensis
Distribution and molecular characterization of tetracycline resistance in Laribacter hongkongensis
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DOI：
10.1093/jac/dkm539
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发表时间：
2008-03-01
影响因子：
5.2
通讯作者：
Yuen, Kwok-Yung
中科院分区：
文献类型：
--
作者：
Lau, Susanna K. P.;Wong, Gilman K. M.;Yuen, Kwok-Yung
目的：香港乳杆菌(Laribacter Hongkongensis)是一种新发现的与胃肠炎有关的细菌，存在于淡水鱼体内。结果：3株人分离株和1株鱼分离株对四环素(MIC128 mg/L)和强力霉素(MIC8~16 mg/L)耐药，对米诺环素(MIC1~4 mg/L)的敏感性降低。从四环素抗性菌株HLHK5中克隆到一个3566bp的基因簇，该基因簇包含TetR和TetA。HLHK5的TetA基因的侧翼区和3‘端与猪衣原体TetC岛的相应区域相同，而TetA基因与转座子Tn1721和革兰氏阴性菌的质粒几乎完全相同，提示HLHK5的TetA/TetR可能是由非法重组产生的。聚合酶链式反应和DNA测序表明，在其他3株四环素耐药的香港产乳杆菌中均存在TETA。对HLHK22菌株的15 665个碱基的质粒pHLHK22进行了测序和鉴定，发现存在一个相似的TetA/TetR基因簇。结论：基因的水平转移，特别是通过Tn1721和相关质粒的水平转移，可能是获得和传播四环素耐药性的一个重要机制。本研究是首次在菊科细菌中鉴定TetA基因。
Objectives: Laribacter hongkongensis is a newly discovered bacterium associated with gastroenteritis and found in freshwater fish. Although isolates resistant to tetracycline have been described, their resistance mechanisms have not been studied.Patients and methods: We describe the distribution and molecular characterization of tetracycline resistance in 48 L. hongkongensis isolates from humans and fish.Results: Three human isolates and one fish isolate were resistant to tetracycline (MIC 128 mg/L) and doxycycline (MIC 8-16 mg/L) and had reduced susceptibility to minocycline (MIC 1-4 mg/L). A 3566 bp gene cluster, which contains tetR and tetA, was cloned from one of the tetracycline-resistant strains, HLHK5. While the flanking regions and 3' end of the tetA of HLHK5 were identical to the corresponding regions of a tetC island in Chlamydia suis, the tetA gene was almost identical to that of transposon Tn1721 and plasmids of Gram-negative bacteria, suggesting that the tetA/tetR of HLHK5 may have arisen from illegitimate recombination. PCR and DNA sequencing showed the presence of tetA in the other three tetracycline-resistant L. hongkongensis strains. Sequencing and characterization of a 15 665 bp plasmid, pHLHK22, from strain HLHK22 revealed the presence of a similar tetA/tetR gene cluster. This novel plasmid also confers tetracycline resistance when transformed to Escherichia coli and other L. hongkongensis isolates.Conclusions: Horizontal transfer of genes, especially through Tn1721 and related plasmids, is likely an important mechanism for acquisition and dissemination of tetracycline resistance in L. hongkongensis. The present study is the first report on identification of tetA genes in bacteria of the Neisseriaceae family.