Qi Wei, Ender Miriam, O'Brien Frances, Imhof Alexander, Ruef Christian, McCallum Nadine, Berger-Bächi Brigitte
Department of Medical Microbiology, University of Zürich, CH-8006 Zürich, Switzerland.
J Clin Microbiol. 2005 Oct;43(10):5164-70. doi: 10.1128/JCM.43.10.5164-5170.2005.
The majority of methicillin-resistant Staphylococcus aureus (MRSA) isolates, recovered in 2003 at the Department of Medical Microbiology in Zürich, Switzerland, belonged to major clones that are circulating worldwide. Staphylococcal cassette chromosome mec type IV (SCCmec-IV), harbored by half of the isolates, was found in sequence type 217 (ST 217), which is an allelic variant of epidemic MRSA-15 (designated EMRSA-15), in a new local ST 617 descending from clonal complex CC 8 and in low-level oxacillin-resistant strains of multiple genetic lineages characteristic of community-onset MRSA. SCCmec-I, SCCmec-II, and SCCmec-III were in the minority, and four MRSA isolates had complex, rearranged SCCmec elements. A novel SCCmec-N1 of approximately 30 kb, associated with a dfrA gene and a ccr 4-related recombinase complex, was identified in a large number of low-level oxacillin-resistant isolates, which descended from the successful clonal complex CC 45 and are spreading among intraveneous drug users. In contrast, the SCCmec types of oxacillin-resistant coagulase-negative staphylococci (MRCNS) were of completely different composition. SCCmec type I (SCCmec-I) and SCCmec-II were more frequent than in the MRSA, while fewer contained SCCmec-IV. The other MRCNS displayed 11 different, complex patterns, suggesting frequent recombination between different SCCmec elements. With one ccr-negative exception, these strains amplified between one and three different ccr products, indicating either new varied complexes or multiple ccr loci. This suggests the presence of novel SCCmec types in MRCNS and no extensive interspecies SCCmec transfer between MRSA and MRCNS.
2003年在瑞士苏黎世医学微生物学系分离出的大多数耐甲氧西林金黄色葡萄球菌（MRSA）菌株，属于在全球传播的主要克隆型。一半的菌株携带葡萄球菌盒式染色体mec IV型（SCCmec-IV），在序列型217（ST 217）中发现，它是流行的MRSA-15（指定为EMRSA-15）的等位基因变体，存在于来自克隆复合体CC 8的新的本地ST 617以及社区获得性MRSA特征的多基因谱系的低水平耐氧西林菌株中。SCCmec-I、SCCmec-II和SCCmec-III占少数，并且有4株MRSA菌株具有复杂的、重排的SCCmec元件。在大量低水平耐氧西林菌株中鉴定出一种约30 kb的新型SCCmec-N1，它与一个dfrA基因和一个ccr 4相关重组酶复合体相关，这些菌株来自成功的克隆复合体CC 45并在静脉吸毒者中传播。相比之下，耐氧西林凝固酶阴性葡萄球菌（MRCNS）的SCCmec类型组成完全不同。SCCmec I型（SCCmec-I）和SCCmec-II比在MRSA中更常见，而含有SCCmec-IV的较少。其他MRCNS显示出11种不同的复杂模式，表明不同SCCmec元件之间频繁重组。除了一个ccr阴性的例外，这些菌株扩增出一到三种不同的ccr产物，表明存在新的不同复合体或多个ccr位点。这表明MRCNS中存在新型SCCmec类型，并且MRSA和MRCNS之间不存在广泛的种间SCCmec转移。
