Mirani Zulfiqar Ali, Khan Muhammad Naseem, Aziz Mubashir, Naz Shagufta, Khan Seema Ismat
Microbiological Analytical Centre, Pakistan Council of Scientific and Industrial Research Laboratories Complex, Karachi.
J Coll Physicians Surg Pak. 2012 Jan;22(1):10-4.
To determine the effect of physical and chemical stress factors e.g. antibiotics, NaCl, glucose, heat shock, cold shock and sonic waves on biofilm formation by icaA positive and negative strains of Methicillin resistant Staphylococcus (S.) aureus.
Experimental study.
Microbiological Analytical Centre, Pakistan Council of Scientific and Industrial Research (PCSIR) Laboratories Complex, Karachi, from January to December 2010.
One strain of Staphylococcus aureus labelled as FA was isolated from a food sample and the other strain labelled as CL was a clinical strain. Biofilm assays were performed in brain-heart infusion (BHI) medium and in BHI supplemented with 7% NaCl, 5% glucose, or sub-inhibitory concentrations of Vancomycin, Oxacillin, Ampicillin, Tetracycline, Erythromycin, Rifampicin and Ciprofloxacin. Polymerase chain reaction (PCR) was used for screening of the icaA and mecA genes.
The FA and CL were identified as MRSA carrying mecA gene. The strain FA showed biofilm formation without any treatment and was found to carry icaA gene contrary to CL, that does not contain this gene therefore, is unable to produce biofilm under normal conditions without any stress. The use of sub-lethal doses of cell wall active antibiotics, exposure to 7% NaCl, sonication, and heat shock were found to augment biofilm quantity in FA, an icaA positive strain and induce biofilm mode of growth in CL, an icaA negative strain. Anti-protein synthesis antibiotics did not show any effect on biofilm formation process in icaA positive or negative strains.
There is a role of anti-cell wall factors i.e. sonication, heat shock, NaCl and antibiotics in the induction of biofilm mode of growth in MRSA and Methicillin sensitive S. aureus. The factors which partially damage bacterial cell wall, equally, induce biofilm formation in icaA positive or negative S. aureus.
确定物理和化学应激因素，如抗生素、氯化钠、葡萄糖、热休克、冷休克和声波，对耐甲氧西林金黄色葡萄球菌icaA阳性和阴性菌株生物膜形成的影响。
实验研究。
2010年1月至12月，位于卡拉奇的巴基斯坦科学与工业研究理事会（PCSIR）实验室综合大楼微生物分析中心。
从一份食品样本中分离出一株标记为FA的金黄色葡萄球菌菌株，另一株标记为CL的菌株为临床菌株。在脑心浸液（BHI）培养基以及添加了7%氯化钠、5%葡萄糖或亚抑菌浓度的万古霉素、苯唑西林、氨苄西林、四环素、红霉素、利福平及环丙沙星的BHI培养基中进行生物膜检测。采用聚合酶链反应（PCR）筛选icaA和mecA基因。
FA和CL被鉴定为携带mecA基因的耐甲氧西林金黄色葡萄球菌。菌株FA未经任何处理即可形成生物膜，且发现其携带icaA基因；与之相反，CL不含有该基因，因此在无任何应激条件下的正常情况下无法产生生物膜。发现使用亚致死剂量的细胞壁活性抗生素、暴露于7%氯化钠、超声处理和热休克可增加icaA阳性菌株FA中的生物膜量，并诱导icaA阴性菌株CL中的生物膜生长模式。抗蛋白质合成抗生素对icaA阳性或阴性菌株的生物膜形成过程未显示任何影响。
抗细胞壁因子，即超声处理、热休克、氯化钠和抗生素，在耐甲氧西林金黄色葡萄球菌和甲氧西林敏感金黄色葡萄球菌生物膜生长模式的诱导中发挥作用。同样，部分破坏细菌细胞壁的因素可诱导icaA阳性或阴性金黄色葡萄球菌形成生物膜。
