Departamento de Microbiologia e Parasitologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
Braz J Med Biol Res. 2009 Oct;42(10):877-81. doi: 10.1590/s0100-879x2009005000018. Epub 2009 Sep 4.
Methicillin-resistant Staphylococcus aureus (MRSA) is a major agent of hospital infections worldwide. In Brazil, a multiresistant MRSA lineage (ST239-SCCmecIIIA), the so-called Brazilian epidemic clone (BEC), has predominated in all regions. However, an increase in nosocomial infections caused by non-multiresistant MRSA clones has recently been observed. In the present study, 45 clinical isolates of MRSA obtained from a university hospital located in Natal city, Brazil, were identified by standard laboratory methods and molecularly characterized using staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was carried out using CLSI methods. The MRSA isolates studied displayed a total of 8 different pulsed-field gel electrophoresis patterns (types A to H) with predominance (73%) of pattern A (BEC-related). However, MRSA harboring SCCmec type IV were also identified, 3 (7%) of which were genetically related to the pediatric clone--USA800 (ST5-SCCmecIV). In addition, we found a considerable genetic diversity within BEC isolates. MRSA displaying SCCmecIV are frequently susceptible to the majority of non-beta-lactam antibiotics. However, emergence of multiresistant variants of USA800 was detected.
耐甲氧西林金黄色葡萄球菌（MRSA）是全球医院感染的主要病原体。在巴西，一种多耐药的 MRSA 谱系（ST239-SCCmecIIIA），即所谓的巴西流行克隆（BEC），已在所有地区占主导地位。然而，最近观察到由非多耐药性 MRSA 克隆引起的医院感染增加。在本研究中，通过标准实验室方法鉴定了来自巴西纳塔尔市一家大学医院的 45 株临床分离的 MRSA，并通过葡萄球菌染色体盒 mec（SCCmec）分型和脉冲场凝胶电泳进行了分子特征分析。使用 CLSI 方法进行了抗菌药物敏感性测试。所研究的 MRSA 分离株显示了总共 8 种不同的脉冲场凝胶电泳模式（类型 A 至 H），其中模式 A（与 BEC 相关）占主导地位（73%）。然而，也鉴定出携带 SCCmec 类型 IV 的 MRSA，其中 3 株（7%）与儿科克隆 USA800（ST5-SCCmecIV）具有遗传相关性。此外，我们发现 BEC 分离株内存在相当大的遗传多样性。携带 SCCmecIV 的 MRSA 通常对大多数非β-内酰胺类抗生素敏感。然而，检测到 USA800 的多耐药变体的出现。
