Namvar Amirmorteza Ebrahimzadeh, Asghari Babak, Ezzatifar Fatemeh, Azizi Gholamreza, Lari Abdolaziz Rastegar
Medical Microbiology Department, Antimicrobial Resistance Research Center, Faculty of Medicine, Iran University of Medical Science, Tehran, Iran.
GMS Hyg Infect Control. 2013 Apr 29;8(1):Doc03. doi: 10.3205/dgkh000203. eCollection 2013.
Staphylococcus aureus is a major hospital and community pathogen having the aptitude to cause a wide variety of infections in men. The ability of microorganisms to produce biofilm facilitates them to withstand the host immune response and is recognized as one factor contributing to chronic or persistent infections. It was demonstrated that the ica-encoded genes lead to the biosynthesis of polysaccharide intercellular adhesion (PIA) molecules, and may be involved in the accumulation phase of biofilm formation. Different studies have shown the decisive role of the ica gene as virulence factors in staphylococcal infections. This study was carried out to demonstrate the relationship between ica gene and production of slime layer in S. aureus strains. Sixty S. aureus strains were isolated from patients. The isolates were identified morphologically and biochemically following standard laboratory methods. After identification, the staphylococcal isolates were maintained in trypticase soy broth (TSB), to which 15% glycerol was added, and stored at -20°C. Slime formation and biofilm assay was monitored. A PCR assay was developed to identify the presence of icaD (intercellular adhesion gene) gene in all isolates. Thirty-nine slime producing colonies with CRA plates (65%) formed black colors, the remaining 21 isolates were pink (35%). In the quantitative biofilm assay 35 (58%) produced biofilm while 25 (42%) isolates did not exhibit this property. All isolates were positive for detection of icaD gene by PCR method. The interaction of icaA and icaD in the investigated isolates may be important in slime layer formation and biofilm phenomena. We propose PCR detection of the ica gene locus as a rapid and effective method to be used for discrimination between potentially virulent and nonvirulent isolates, with implications for therapeutic and preventive measures pertainin to the management of colonized indwelling catheters.
金黄色葡萄球菌是一种主要的医院和社区病原体，有能力在男性中引起各种各样的感染。微生物产生生物膜的能力有助于它们抵御宿主免疫反应，并且被认为是导致慢性或持续性感染的一个因素。已证明ica编码基因导致胞间多糖黏附素（PIA）分子的生物合成，并且可能参与生物膜形成的聚集阶段。不同研究表明ica基因作为毒力因子在葡萄球菌感染中起决定性作用。本研究旨在证明ica基因与金黄色葡萄球菌菌株黏液层产生之间的关系。从患者中分离出60株金黄色葡萄球菌菌株。按照标准实验室方法对分离株进行形态学和生化鉴定。鉴定后，将葡萄球菌分离株保存在添加了15%甘油的胰蛋白酶大豆肉汤（TSB）中，并储存在-20°C。监测黏液形成和生物膜检测。开发了一种PCR检测方法来鉴定所有分离株中icaD（胞间黏附基因）基因的存在。用CRA平板检测，39个产生黏液的菌落（65%）形成黑色，其余21个分离株为粉红色（35%）。在定量生物膜检测中，35个（58%）产生生物膜，而25个（42%）分离株未表现出这种特性。通过PCR方法检测，所有分离株的icaD基因均为阳性。在所研究的分离株中，icaA和icaD的相互作用在黏液层形成和生物膜现象中可能很重要。我们建议将ica基因位点的PCR检测作为一种快速有效的方法，用于区分潜在的有毒力和无毒力分离株，这对与留置导管定植管理相关的治疗和预防措施具有重要意义。
