Department of Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India.
Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Coimbatore, Tamil Nadu, India.
Exp Eye Res. 2018 Sep;174:1-12. doi: 10.1016/j.exer.2018.05.011. Epub 2018 May 14.
The conjunctival sac of healthy human harbours a variety of microorganisms. When the eye is compromised, an occasional inadvertent spread happens to the adjacent tissue, resulting in bacterial ocular infections. Microbiological investigation of the conjunctival swab is one of the broadly used modality to study the aetiological agent of conjunctiva. However, most of the time such methods yield unsatisfactory results. Hence, the present study intends to identify the bacterial community in human conjunctiva of pre-operative subjects through 16S rRNA gene libraries. Out of 45 samples collected from preoperative patients undergoing cataract surgery, 36 libraries were constructed with bacterial nested-PCR-positive samples. The representative clones with unique restriction pattern were generated through Amplified Ribosomal DNA Restriction Analysis (ARDRA) which were sequenced for phylogenetic affiliation. A total of 211 representative clones were obtained which were distributed in phyla Actinobacteria, Firmicutes, α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Bacteroidetes, and Deinococcus-Thermus. Findings revealed the presence of polybacterial community, especially in some cases even though no bacterium or a single bacterium alone was identified through cultivable method. Remarkably, we identified 17 species which have never been reported in any ocular infections. The sequencing data reported 6 unidentified bacteria suggesting the possibility of novel organisms in the sample. Since, polybacterial community has been identified consisting of both gram positive and gram negative bacteria, a broad spectrum antibiotic therapy is advisable to the patients who are undergoing cataract surgery. Consolidated effort would significantly improve a clear understanding of the nature of microbial community in the human conjunctiva which will promote administration of appropriate antibiotic regimen and also help in the development of oligonucleotide probes to screen the predominant pathogens for early predisposition.
健康人眼的结膜囊中存在多种微生物。当眼睛受损时，偶尔会不经意地扩散到相邻组织，导致细菌性眼部感染。结膜拭子的微生物学检查是研究结膜病因的广泛应用方法之一。然而，大多数时候这些方法的结果并不令人满意。因此，本研究旨在通过 16S rRNA 基因文库鉴定术前患者人结膜中的细菌群落。在从接受白内障手术的术前患者中收集的 45 个样本中，用细菌嵌套 PCR 阳性样本构建了 36 个文库。通过扩增核糖体 DNA 限制性分析 (ARDRA) 生成具有独特限制性模式的代表性克隆，然后对其进行测序以确定系统发育归属。共获得 211 个代表性克隆，分布在放线菌门、厚壁菌门、α-变形菌门、β-变形菌门、γ-变形菌门、拟杆菌门和 Deinococcus-Thermus 门。研究结果表明存在多细菌群落，特别是在某些情况下，即使通过可培养方法未鉴定出任何细菌或单一细菌。值得注意的是，我们鉴定出了 17 种从未在任何眼部感染中报道过的物种。测序数据报告了 6 种未识别的细菌，这表明样本中可能存在新的生物体。由于已经鉴定出的多细菌群落同时包含革兰氏阳性菌和革兰氏阴性菌，因此建议接受白内障手术的患者进行广谱抗生素治疗。综合努力将显著提高对人结膜中微生物群落性质的清晰认识，这将有助于制定适当的抗生素治疗方案，并有助于开发寡核苷酸探针来筛选主要病原体，以早期进行倾向性筛查。
