Ebrahim-Saraie Hadi Sedigh, Motamedifar Mohammad, Sarvari Jamal, Hoseini Alfatemi Seyedeh Mahsan
Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran ; Shiraz HIV/AIDS Research Center, Shiraz University of Medical Sciences, Shiraz, IR Iran.
Jundishapur J Microbiol. 2015 Jun 27;8(6):e16998. doi: 10.5812/jjm.16998v2. eCollection 2015 Jun.
Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major cause of nosocomial infections. Methicillin resistance in S. aureus is caused by the acquisition of the mecA gene, located on a mobile genetic element called the staphylococcal cassette chromosome (SCC).
The aim of this study was to evaluate the presence of the predominant SCCmec type present among clinical isolates.
This cross-sectional study was performed on a total of 146 MRSA isolates obtained from clinical specimens between 2012 and 2013 from two major hospitals in Shiraz, Southwest of Iran. Antibiotic susceptibility profiles were determined by the disc diffusion method according to the guidelines of The Clinical and Laboratory Standards Institute. Bacterial DNA was extracted using the small-scale phenol-chloroform extraction method and was employed as polymerase chain reaction (PCR) templates for the assigned current SCCmec types.
The assigned SCCmec types by PCR revealed the SCCmec type I as the predominant type with 86 (58.9%) samples, followed by the SCCmec type II with 29 (19.9%), type III with 16 (11.0%), and type IV with 12 (8.2%) samples, respectively. The SCCmec type I MRSA isolates were significantly recovered from blood (80%) and sputum (67.2%). The results of antibacterial susceptibility tests for the MRSA isolates showed that all of those carrying the SCCmec type I and II had significantly greater resistance rates to Gentamicin and Rifampin than the isolates containing the SCCmec type III. Also, a significant difference was detected for susceptibility to Co-trimoxazole between the SCCmec type I and II MRSA isolates and the SCCmec type III, which was more resistant.
The frequency of the isolates containing type I in the current study can indicate an emergence of this SCCmec type in the studied medical centers.
耐甲氧西林金黄色葡萄球菌（MRSA）仍然是医院感染的主要原因。金黄色葡萄球菌中的甲氧西林耐药性是由位于一种称为葡萄球菌盒式染色体（SCC）的移动遗传元件上的mecA基因获得所致。
本研究的目的是评估临床分离株中主要的SCCmec类型的存在情况。
本横断面研究共对2012年至2013年间从伊朗西南部设拉子的两家主要医院的临床标本中获得的146株MRSA分离株进行。根据临床和实验室标准研究所的指南，采用纸片扩散法测定抗生素敏感性谱。使用小规模酚-氯仿提取法提取细菌DNA，并将其用作指定的当前SCCmec类型的聚合酶链反应（PCR）模板。
通过PCR确定的SCCmec类型显示，SCCmec I型为主要类型，有86份（58.9%）样本，其次是SCCmec II型，有29份（19.9%），III型有16份（11.0%），IV型有12份（8.2%）样本。SCCmec I型MRSA分离株显著从血液（80%）和痰液（67.2%）中分离得到。MRSA分离株的抗菌药敏试验结果表明，所有携带SCCmec I型和II型的菌株对庆大霉素和利福平的耐药率均显著高于含有SCCmec III型的菌株。此外，SCCmec I型和II型MRSA分离株与更耐药的SCCmec III型之间在对复方新诺明的敏感性方面也检测到显著差异。
本研究中含I型的分离株频率表明该SCCmec类型在研究的医疗中心出现。
