Lishui Central Hospital, Zhejiang, PR China.
Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, PR China.
J Med Microbiol. 2013 Aug;62(Pt 8):1199-1203. doi: 10.1099/jmm.0.058305-0. Epub 2013 May 2.
Fusidic acid (FA) resistance in Staphylococcus aureus markedly varied among different regions. Few data for FA resistance are available in China. In this study, FA susceptibility testing was performed, and the prevalence of fusB and fusC in 116 clinical isolates of S. aureus was investigated by PCR. Mutations in fusA were also determined by sequencing of PCR products. Molecular typing of fusB-positive strains was based on multilocus sequence typing (MLST), spa typing and pulsed-field gel electrophoresis (PFGE). A DNA fragment flanking fusB was sequenced. Transformation experiments were carried out in fusB-positive S. aureus. Of 116 S. aureus including 19 meticillin-resistant S. aureus (MRSA) and 97 meticillin-susceptible S. aureus (MSSA), four (3.5 %) were resistant to FA with MICs of 6-12 µg ml(-1), including one MRSA from blood and three MSSA from wound exudates. All four FA-resistant isolates were found to be fusB gene positive. Three FA-resistant MSSA strains had the same MLST profile of ST630 and spa type of t377, whilst the MRSA strain belonged to ST630-t4549. Only one PFGE pattern was recognized for these four strains. No fusC and fusA mutations were detected in any of the isolates. FA resistance in fusB-positive clinical isolates could be transferred to S. aureus RN4220. The fusB gene was located in a transposon-like element, which had 99 % identity with that found in pUB101. In conclusion, the FA resistance rate is low in S. aureus, and the fusB gene is responsible for the resistance.
葡萄球菌酸（FA）耐药性在不同地区有显著差异。中国有关 FA 耐药性的数据很少。在本研究中，我们进行了 FA 药敏试验，并通过 PCR 检测了 116 株金黄色葡萄球菌临床分离株中 fusB 和 fusC 的流行情况。通过 PCR 产物测序还确定了 fusA 突变。fusB 阳性株的分子分型基于多位点序列分型（MLST）、spa 分型和脉冲场凝胶电泳（PFGE）。测序了 fusB 侧翼的 DNA 片段。在 fusB 阳性的金黄色葡萄球菌中进行了转化实验。在 116 株金黄色葡萄球菌中，包括 19 株耐甲氧西林金黄色葡萄球菌（MRSA）和 97 株甲氧西林敏感金黄色葡萄球菌（MSSA），有 4 株（3.5%）对 FA 耐药，MIC 值为 6-12μg/ml，其中 1 株来自血液的 MRSA 和 3 株来自伤口渗出液的 MSSA。所有 4 株 FA 耐药分离株均为 fusB 基因阳性。3 株 FA 耐药 MSSA 菌株具有相同的 ST630 型和 t377 spa 型，而 MRSA 菌株属于 ST630-t4549。这 4 株菌只有一种 PFGE 图谱。在所有分离株中均未检测到 fusC 和 fusA 突变。fusB 阳性临床分离株中的 FA 耐药性可转移至金黄色葡萄球菌 RN4220。fusB 基因位于一个转座子样元件中，与 pUB101 中的基因具有 99%的同源性。结论：金黄色葡萄球菌中 FA 耐药率较低，fusB 基因是耐药的原因。
