Pinna A, Sechi L A, Zanetti S, Delogu D, Carta F
Institute of Ophthalmology, University of Sassari, Sassari, Italy.
Ophthalmology. 2000 Dec;107(12):2162-6. doi: 10.1016/s0161-6420(00)00408-5.
To investigate the adherence of two clinically relevant ocular isolates of Staphylococcus epidermidis to ACRYSOF intraocular lenses (IOLs) (Alcon Surgical, Fort Worth, Texas) and to determine whether the strains under study carried the intercellular adhesion (ica) locus, which encodes production of S. epidermidis antigens mediating adherence to biomaterials.
Experimental study.
The authors examined the in vitro adherence of two clinically relevant ocular isolates of S. epidermidis (S. epidermidis 1 and S. epidermidis 2). Adherence was tested on six ACRYSOF IOLs.
Three IOLs were placed in three separate test tubes containing 5 ml of S. epidermidis 1 suspension, and three other IOLs were placed in three test tubes containing 5 ml of S. epidermidis 2 suspension. At different times (3, 30, and 90 minutes), the IOLs were removed from the test tubes and rinsed in sterile phosphate buffered solution. The lenses were then fixed in glutaraldehyde, postfixed in osmium tetroxide, and serially dehydrated in ethyl alcohol. After critical point drying, they were sputter-coated with gold and then examined with a scanning electron microscope. In addition, polymerase chain reaction amplification was used to investigate whether the isolates under study carried the ica locus.
The number of adhered bacteria per area (square millimeters) of IOL optic was calculated. Statistical analysis included calculation of arithmetic means and 95% confidence intervals (t test). Polymerase chain reaction amplification products were visualized in ethidium bromide-stained agarose gel.
Direct counting of adherent bacteria in scanning electron microscopy photographs revealed that the total amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes of incubation in bacterial suspension was 1306/mm(2), 3389/mm(2), and 7195/mm(2) (S. epidermidis 1) and 778/mm(2), 1056/mm(2), and 3861/mm(2) (S. epidermidis 2). Differences at 30 and 90 minutes were statistically significant (P: = 0.01 and 0.02, respectively). Polymerase chain reaction amplification revealed that S. epidermidis 1 contained the ica locus, whereas S. epidermidis 2 was ica negative.
Different ocular isolates of S. epidermidis may differ significantly with regard to adherence to ACRYSOF IOLs. Adherence appeared to be greater when the bacterial DNA contained the ica locus. Strains of S. epidermidis carrying the ica locus may play an important role in the pathogenesis of some forms of endophthalmitis occurring after cataract surgery.
研究两种临床相关的表皮葡萄球菌眼部分离株对爱尔康公司生产的（美国得克萨斯州沃思堡）丙烯酸酯人工晶状体（IOL）的黏附情况，并确定所研究的菌株是否携带细胞间黏附（ica）基因座，该基因座编码介导表皮葡萄球菌黏附于生物材料的抗原的产生。
实验性研究。
作者检测了两种临床相关的表皮葡萄球菌眼部分离株（表皮葡萄球菌1和表皮葡萄球菌2）的体外黏附情况。在6个丙烯酸酯人工晶状体上进行了黏附测试。
将3个人工晶状体分别置于3个装有5毫升表皮葡萄球菌1悬液的单独试管中，另外3个人工晶状体置于3个装有5毫升表皮葡萄球菌2悬液的试管中。在不同时间点（3分钟、30分钟和90分钟），从试管中取出人工晶状体，用无菌磷酸盐缓冲液冲洗。然后将晶状体用戊二醛固定，四氧化锇后固定，并在乙醇中依次脱水。临界点干燥后，进行金溅射镀膜，然后用扫描电子显微镜检查。此外，采用聚合酶链反应扩增来研究所研究的分离株是否携带ica基因座。
计算人工晶状体光学部每单位面积（平方毫米）黏附的细菌数量。统计分析包括计算算术平均值和95%置信区间（t检验）。聚合酶链反应扩增产物在溴化乙锭染色的琼脂糖凝胶中进行可视化分析。
扫描电子显微镜照片中对黏附细菌的直接计数显示，在细菌悬液中孵育3分钟、30分钟和90分钟后，人工晶状体光学部每单位面积黏附的细菌总量分别为1306个/mm²、3389个/mm²和7195个/mm²（表皮葡萄球菌1）以及778个/mm²、1056个/mm²和3861个/mm²（表皮葡萄球菌2）。30分钟和90分钟时的差异具有统计学意义（P值分别为0.01和0.02）。聚合酶链反应扩增显示表皮葡萄球菌1含有ica基因座，而表皮葡萄球菌2为ica阴性。
不同的表皮葡萄球菌眼部分离株对丙烯酸酯人工晶状体的黏附情况可能存在显著差异。当细菌DNA含有ica基因座时，黏附似乎更强。携带ica基因座的表皮葡萄球菌菌株可能在白内障手术后发生的某些形式的眼内炎的发病机制中起重要作用。
