Lee Ching Ching, Lee Vivian W Y, Chan Francis K L, Ling Thomas K W
Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, SAR, China.
Chemotherapy. 2008;54(1):50-3. doi: 10.1159/000112416. Epub 2007 Dec 10.
Fluoroquinolone-resistant Helicobacter pylori emerged in 1995 and the resistance was due to point mutation in the gyrA gene. In this study we investigate the resistance mechanism and the antimicrobial susceptibilities of clarithromycin, metronidazole, amoxicillin, tetracycline and telithromycin against levofloxacin-resistant H. pylori in Hong Kong.
One hundred and ninety-one nonduplicate H. pylori isolates were collected during 2004 and 2005, and 25 isolates with levofloxacin zone sizes less than 30 mm were selected for minimal inhibitory concentration determination by agar dilution, gyrA gene amplication and sequencing the amplified gyrA gene.
The prevalence of levofloxacin-resistant H. pylori was 11.5% (22/191). Among these levofloxacin-resistant strains, 7 (31.8%) and 10 (45.5%) were resistant to clarithromycin and metronidazole, respectively, 17 (77.3%) had point mutations in gyrA gene at amino acids 87, 91 and 130 and the most frequent mutation point was at position 91.
Amoxicillin, tetracycline and telithromycin were active against levofloxacin-resistant H. pylori and levofloxacin resistance was mainly due to point mutation in the gyrA gene, especially at amino acid position 91.
耐氟喹诺酮幽门螺杆菌于1995年出现，其耐药性归因于gyrA基因的点突变。在本研究中，我们调查了香港地区克拉霉素、甲硝唑、阿莫西林、四环素和替利霉素对左氧氟沙星耐药幽门螺杆菌的耐药机制及抗菌敏感性。
在2004年至2005年期间收集了191株非重复的幽门螺杆菌分离株，选择25株左氧氟沙星抑菌圈直径小于30 mm的分离株，采用琼脂稀释法测定最低抑菌浓度，进行gyrA基因扩增并对扩增后的gyrA基因进行测序。
左氧氟沙星耐药幽门螺杆菌的流行率为11.5%（22/191）。在这些左氧氟沙星耐药菌株中，分别有7株（31.8%）和10株（45.5%）对克拉霉素和甲硝唑耐药，17株（77.3%）的gyrA基因在第87、91和130位氨基酸处存在点突变，最常见的突变位点在第91位。
阿莫西林、四环素和替利霉素对左氧氟沙星耐药幽门螺杆菌有活性，左氧氟沙星耐药主要归因于gyrA基因的点突变，尤其是在第91位氨基酸处。
