O'Brien F G, Lim T T, Chong F N, Coombs G W, Enright M C, Robinson D A, Monk A, Saïd-Salim B, Kreiswirth B N, Grubb W B
Gram-Positive Bacteria Typing and Research Unit, Curtin University of Technology, School of Biomedical Sciences, GPO Box U1987, Perth, Western Australia 6845, Australia.
J Clin Microbiol. 2004 Jul;42(7):3185-90. doi: 10.1128/JCM.42.7.3185-3190.2004.
Community methicillin-resistant Staphylococcus aureus (CMRSA) strains are being isolated with increasing frequency around the world. In Western Australia CMRSA are endemic in geographically remote communities and have been found to belong to five different contour-clamped homogeneous electric field (CHEF) electrophoretic patterns. Representatives of each of these CHEF patterns have been compared to CMRSA representative of CHEF patterns from other Australian states and New Zealand. With one exception, all of the isolates were nonmultiresistant and were not resistant to many antimicrobial agents other than the beta-lactams. With one exception, which is not believed to be a CMRSA, all of the isolates harbored a beta-lactamase plasmid. Erythromycin resistance was associated with a 2-kb plasmid. One of the beta-lactamase plasmids was found to be able to acquire additional resistance determinants to become a multiple resistance plasmid. There were 10 multilocus sequence types belonging to eight distantly related clonal complexes of S. aureus. One new sequence type was found. Although most of the CMRSA harbored the type IVa SCCmec, a type IV structural variant was found and two new SCCmec types were identified. Protein A gene (spa) typing revealed two new spa types and, with two exceptions, corresponded to multilocus sequence typing. In contrast to other reports on CMRSA, most of the CMRSA strains studied here did not contain the Panton-Valentine leukocidin genes. The results also demonstrate that nonmultiresistant hospital strains such as UK EMRSA-15 may be able to circulate in the community and could be mistaken for CMRSA based on their resistance profiles.
社区耐甲氧西林金黄色葡萄球菌(CMRSA)菌株在全球范围内的分离频率日益增加。在西澳大利亚,CMRSA在地理上偏远的社区中呈地方性流行,并且已发现它们属于五种不同的轮廓夹闭均匀电场(CHEF)电泳模式。已将这些CHEF模式中的每种模式的代表与来自澳大利亚其他州和新西兰的CHEF模式的CMRSA代表进行了比较。除了一个例外,所有分离株均为非多重耐药,并且除β-内酰胺类药物外,对许多抗菌药物均无耐药性。除了一个不被认为是CMRSA的例外,所有分离株都携带β-内酰胺酶质粒。红霉素耐药性与一个2kb的质粒有关。发现其中一种β-内酰胺酶质粒能够获得额外的耐药决定簇,从而成为多重耐药质粒。有10个多位点序列类型属于金黄色葡萄球菌的8个远缘相关克隆复合体。发现了一种新的序列类型。尽管大多数CMRSA携带IVa型葡萄球菌染色体盒式甲氧西林耐药基因元件(SCCmec),但发现了一种IV型结构变体,并鉴定出两种新的SCCmec类型。蛋白A基因(spa)分型揭示了两种新的spa类型,除了两个例外,与多位点序列分型相对应。与其他关于CMRSA的报道相反,这里研究的大多数CMRSA菌株不包含杀白细胞素基因。结果还表明,非多重耐药的医院菌株,如英国的EMRSA-15,可能能够在社区中传播,并且基于它们的耐药谱可能会被误认为是CMRSA。