Srifuengfung Somporn, Tribuddharat Chanwit, Chokephaibulkit Kulkanya, Comerungsee Sopita
Department of Microbiology, Faculty of Medicine Siriraj Hopital, Mahidol University, Bangkok, Thailand.
J Med Assoc Thai. 2010 Nov;93 Suppl 5:S35-9.
The most frequent markers of fluoroquinolone resistance in S. pneumoniae are chromosomal mutations in the quinolone-resistance-determining regions of DNA gyrase and topoisomerase IV encoding for the gyrA, gyrB and parC, parE genes. In 2008, 6.5% of the Streptococcus pneumoniae isolates in a Bangkok university hospital were resistant to ofloxacin. Using PCR and DNA sequencing, we identified mutations in both the gyrA and parC genes of four ofloxacin- and ciprofloxacin-resistant S. pneumoniae isolates (minimum inhibitory concentrations > 32 microg/ml). Mutations were found in the gyrA gene at positions Ser81Phe, Glu85Gly, Glu85Lys and in the parC gene at position Ser79Tyr. Three isolates had mutations in both genes. Two of the isolates were serotype 6B and two were serotypes not contained in currently licensed pneumococcal vaccines. This is the first report of the mechanisms of fluoroquinolone resistance in S. pneumoniae in Thailand.
肺炎链球菌中氟喹诺酮耐药性最常见的标志物是DNA旋转酶和拓扑异构酶IV的喹诺酮耐药决定区域中的染色体突变，这些区域编码gyrA、gyrB以及parC、parE基因。2008年，曼谷一家大学医院分离出的肺炎链球菌中有6.5%对氧氟沙星耐药。通过聚合酶链反应（PCR）和DNA测序，我们在4株对氧氟沙星和环丙沙星耐药的肺炎链球菌分离株（最低抑菌浓度>32微克/毫升）的gyrA和parC基因中均鉴定出了突变。在gyrA基因中发现了Ser81Phe、Glu85Gly、Glu85Lys位点的突变，在parC基因中发现了Ser79Tyr位点的突变。3株分离株的两个基因均有突变。其中2株分离株为6B血清型，另外2株为目前已获许可的肺炎球菌疫苗中未包含的血清型。这是泰国关于肺炎链球菌氟喹诺酮耐药机制的首次报道。
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