Saiful Azmi Johari, Mastura Mohtar, Zarizal Suhaili, Mazurah Mohamed Isa, Shuhaimi Mustafa, Ali Abdul Manaf
Antimicrobial Laboratory, Medicinal Plants Programme, Forest Biotechnology Division, Forest Research Institute Malaysia (FRIM), Selangor, Malaysia.
J Basic Microbiol. 2008 Aug;48(4):245-51. doi: 10.1002/jobm.200700387.
Efflux-mediated resistance has been recognized as an important contributor of antibiotic resistance in bacteria, especially in methicillin-resistant Staphylococcus aureus (MRSA) isolates. This study was carried out to detect and analyze efflux genes (norA and mdeA) and active efflux activity in a collection of Malaysian MRSA and methicillin-sensitive S. aureus (MSSA) clinical isolates. Nineteen isolates including three ATCC S. aureus reference strains were subjected to PCR detection and DNA sequence analysis for norA and mdeA and active efflux detection using modified minimum inhibitory concentration (MIC) assay. From the 19 isolates, 18 isolates harboured the mdeA gene while 16 isolates contained norA gene. DNA sequence analysis reveals 98-100% correlation between the PCR product and the published DNA sequences in GenBank. In addition, 16 isolates exhibited active efflux activity using the ethidium bromide (EtBr)-reserpine combination MIC assay. To our knowledge, this is the first report on the detection of efflux genes and active efflux activity amongst Malaysian clinical isolates of MRSA/MSSA. Detection of active efflux activity may explain the previous report on efflux-mediated drug resistance profile amongst the local clinical isolates.
外排介导的耐药性已被认为是细菌抗生素耐药性的一个重要因素，尤其是在耐甲氧西林金黄色葡萄球菌（MRSA）分离株中。本研究旨在检测和分析马来西亚MRSA和甲氧西林敏感金黄色葡萄球菌（MSSA）临床分离株中的外排基因（norA和mdeA）以及活性外排活性。对包括三株ATCC金黄色葡萄球菌参考菌株在内的19株分离株进行了norA和mdeA的PCR检测、DNA序列分析，并使用改良的最低抑菌浓度（MIC）测定法进行活性外排检测。在这19株分离株中，18株含有mdeA基因，16株含有norA基因。DNA序列分析显示PCR产物与GenBank中公布的DNA序列之间的相关性为98 - 100%。此外，使用溴化乙锭（EtBr）-利血平联合MIC测定法，16株分离株表现出活性外排活性。据我们所知，这是关于马来西亚MRSA/MSSA临床分离株中外排基因和活性外排活性检测的首次报告。活性外排活性的检测可能解释了先前关于当地临床分离株中外排介导的耐药谱的报告。
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