Huang Hui, Zhou Jiandang, Nie Xinmin, Yi Qifeng
Department of Nursing, Third Xiangya Hospital, Central South University, Changsha 410013, China.
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2012 Jun;37(6):567-71. doi: 10.3969/j.issn.1672-7347.2012.06.005.
To investigate the mechanisms by which MecA gene expression leads to β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA), and to study the resistance mechanism of MRSA at the molecular level.
A variety of molecular biological techniques were employed, including screening MRSA using cefoxitin paper disk method, extraction of MRSA mRNA, reverse transcription into cDNA, real-time fluorescence PCR for quantitation of MecA gene expression, and agar dilution method for assessment of minimum inhibitory concentrations in MRSA treated with cefoxitin, oxacillin, vancomycin, or linezolid.
According to the level of resistance of MRSA to cefoxitin, 40 MRSA strains were divided into a low resistance group (n=12), a middle resistance group (n=15), and a high resistance group (n=13). The expression level of the MecA gene in the low resistance group, the middle resistance group, and the high resistance group was 58.87±30.30, 363.37±200.05, and 1257.72±446.63, respectively. MRSA resistance to cefoxitin and oxacillin was 100%; MRSA resistance to vancomycin or linezolid could not be detected. For all 40 MRSA strains the MIC90 for vancomycin was 2.0 μg/mL.
MecA gene expression levels may correlate with the MRSA level of resistance to cefoxitin within a certain range of concentration.
探讨MecA基因表达导致耐甲氧西林金黄色葡萄球菌（MRSA）对β-内酰胺类抗生素耐药的机制，从分子水平研究MRSA的耐药机制。
采用多种分子生物学技术，包括用头孢西丁纸片法筛选MRSA、提取MRSA的mRNA、逆转录成cDNA、实时荧光定量PCR检测MecA基因表达量，以及用琼脂稀释法测定头孢西丁、苯唑西林、万古霉素或利奈唑胺处理的MRSA的最低抑菌浓度。
根据MRSA对头孢西丁的耐药水平，将40株MRSA菌株分为低耐药组（n = 12）、中耐药组（n = 15）和高耐药组（n = 13）。低耐药组、中耐药组和高耐药组的MecA基因表达量分别为58.87±30.30、363.37±200.05和1257.72±446.63。MRSA对头孢西丁和苯唑西林的耐药率为100%；未检测到MRSA对万古霉素或利奈唑胺的耐药情况。40株MRSA菌株对万古霉素的MIC90为2.0μg/mL。
在一定浓度范围内，MecA基因表达水平可能与MRSA对头孢西丁的耐药水平相关。
