Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States.
Infectious Disease Institute, Harvard Medical School, Boston, MA, United States.
Front Public Health. 2020 Jun 3;8:204. doi: 10.3389/fpubh.2020.00204. eCollection 2020.
Methicillin-resistant (MRSA) is a common cause of severe and difficult to treat ocular infection. In this study, the population structure of 68 ocular MRSA isolates collected at Massachusetts Eye and Ear between January 2014 and June 2016 was assessed. By using a combination of multilocus sequence typing (MLST) analysis, SCC typing and detection of the panton-valentine leukocidin (PVL) gene, we found that the population structure of ocular MRSA is composed of lineages with community and hospital origins. As determined by eBURST analysis of MLST data, the ocular MRSA population consisted of 14 different sequence types (STs) that grouped within two predominant clonal complexes: CC8 (47.0%) and CC5 (41.2%). Most CC8 strains were ST8, harbored type IV SCC and were positive for the PVL-toxin (93.7%). The CC5 group was divided between strains carrying SCC type II (71.4%) and SCC type IV (28.6%). Remaining isolates grouped in 6 different clonal complexes with 3 isolates in CC6 and the other clonal complexes being represented by a single isolate. Interestingly, major MRSA CC5 and CC8 lineages were isolated from discrete ocular niches. Orbital and preseptal abscess/cellulitis were predominantly caused by CC8-SCC IV PVL-positive strains. In contrast, infections of the cornea, conjunctiva and lacrimal system were associated with the MDR CC5 lineage, particularly as causes of severe infectious keratitis. This niche specialization of MRSA is consistent with a model where CC8-SCC IV PVL-positive strains are better adapted to cause infections of the keratinized and soft adnexal eye tissues, whereas MDR CC5 appear to have greater ability in overcoming innate defense mechanisms of the wet epithelium of the ocular surface.
耐甲氧西林金黄色葡萄球菌（MRSA）是一种常见的严重且难以治疗的眼部感染病原体。本研究评估了 2014 年 1 月至 2016 年 6 月期间在马萨诸塞眼耳医院采集的 68 株眼部 MRSA 分离株的种群结构。通过使用多位点序列分型（MLST）分析、SCC 分型和检测潘顿-瓦伦丁白细胞毒素（PVL）基因的组合，我们发现眼部 MRSA 的种群结构由具有社区和医院起源的谱系组成。通过对 MLST 数据的 eBURST 分析，眼部 MRSA 种群由 14 个不同的序列型（ST）组成，这些 ST 聚集在两个主要的克隆复合体中：CC8（47.0%）和 CC5（41.2%）。大多数 CC8 菌株为 ST8，携带 IV 型 SCC，且对 PVL 毒素呈阳性（93.7%）。CC5 组分为携带 SCC 型 II（71.4%）和 SCC 型 IV（28.6%）的菌株。其余分离株分组在 6 个不同的克隆复合体中，3 株在 CC6，其他克隆复合体由单个分离株代表。有趣的是，主要的 MRSA CC5 和 CC8 谱系从离散的眼部生态位中分离出来。眶和眶前脓肿/蜂窝织炎主要由 CC8-SCC IV PVL 阳性菌株引起。相比之下，角膜、结膜和泪液系统的感染与 MDR CC5 谱系相关，尤其是作为严重感染性角膜炎的病因。这种 MRSA 的生态位特化与以下模型一致，即 CC8-SCC IV PVL 阳性菌株更适合引起角蛋白化和柔软附属眼部组织的感染，而 MDR CC5 似乎具有更大的能力来克服眼部表面湿润上皮的固有防御机制。
