Messina C, Cafiso V, Campanile F, Santagati M, Stefani S
Department of Microbiological and Gynaecological Sciences-University of Catania, Italy.
New Microbiol. 2001 Oct;24(4):347-53.
A panel of 150 clinical isolates of methicillin resistant and susceptible Staphylococci were investigated using a rapid and simple PCR-RFLPs technique to detect DNA nucleotide changes at the site of the most frequently reported mutations in grlA (codons 79, 80) and gyrA (codons 83, 84) genes which confer fluorquinolone resistance in Staphylococci. Convergent dual mutations in and gyrA and grlA were found in all strains exhibiting resistance to ciprofloxacin (MIC, 8 to > or =128 mg/l) and levofloxacin (MIC, 8 to > or =64 mg/l). Mutations in grlA and gyrA were also found in strains susceptible to levofloxacin and resistant to ciprofloxacin. In our sample no strains with only grlA mutations were found. Our data indicate that methicillin-resistant fluorquinolone-resistant strains are likely to have mutations in both grlA and gyrA. In contrast, methicillin-susceptible strains do not show any mutation. The genetic relatedness of a sample of representative epidemiologically unrelated MRSA strains, tested by PFGE and rep-PCR, are in agreement with the hypothesis of a clonal selection of these resistant strains.
使用一种快速简便的聚合酶链反应-限制性片段长度多态性（PCR-RFLPs）技术，对150株耐甲氧西林和敏感葡萄球菌的临床分离株进行了研究，以检测葡萄球菌中最常报道的赋予氟喹诺酮耐药性的grlA（密码子79、80）和gyrA（密码子83、84）基因位点的DNA核苷酸变化。在所有对环丙沙星（MIC，8至≥128mg/L）和左氧氟沙星（MIC，8至≥64mg/L）耐药的菌株中，均发现了gyrA和grlA中的趋同双突变。在对左氧氟沙星敏感但对环丙沙星耐药的菌株中也发现了grlA和gyrA的突变。在我们的样本中，未发现仅存在grlA突变的菌株。我们的数据表明，耐甲氧西林的氟喹诺酮耐药菌株可能在grlA和gyrA中均有突变。相比之下，甲氧西林敏感菌株未显示任何突变。通过脉冲场凝胶电泳（PFGE）和重复序列聚合酶链反应（rep-PCR）检测的一组具有代表性的、流行病学上无关的耐甲氧西林金黄色葡萄球菌（MRSA）菌株样本的遗传相关性，与这些耐药菌株的克隆选择假说一致。
