Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami-Miller School of Medicine, Miami, Florida 33136, USA.
Ophthalmology. 2010 Mar;117(3):445-52, 452.e1-3. doi: 10.1016/j.ophtha.2009.08.033. Epub 2010 Jan 19.
To determine the presence of 4 clinically relevant bacterial endosymbionts in Acanthamoeba isolates obtained from patients with Acanthamoeba keratitis (AK) and the possible contribution of endosymbionts to the pathogenesis of AK.
Experimental study.
Acanthamoeba isolates (N = 37) recovered from the cornea and contact lens paraphernalia of 23 patients with culture-proven AK and 1 environmental isolate.
Acanthamoeba isolates were evaluated for the presence of microbial endosymbionts belonging to the bacterial genera Legionella, Pseudomonas, Mycobacterium, and Chlamydia using molecular techniques (polymerase chain reaction and sequence analysis, fluorescence in situ hybridization) and transmission electron microscopy. Corneal toxicity and virulence of Acanthamoeba isolates with and without endosymbionts were compared using a cytopathic effect (CPE) assay on human corneal epithelial cells in vitro. Initial visual acuity, location and characteristics of the infiltrate, time to detection of the infection, and symptom duration at presentation were evaluated in all patients.
Prevalence and potential pathobiology of bacterial endosymbionts detected in Acanthamoeba isolates recovered from AK.
Twenty-two (59.4%) of the 38 cultures examined contained at least 1 bacterial endosymbiont. One isolate contained 2 endosymbionts, Legionella and Chlamydia, confirmed by fluorescence in situ hybridization. Corneal toxicity (CPE) was significantly higher for Acanthamoeba-hosting endosymbionts compared with isolates without endosymbionts (P<0.05). Corneal pathogenic endosymbionts such as Pseudomonas and Mycobacterium enhanced Acanthamoeba CPE significantly more than Legionella (P<0.05). In the presence of bacterial endosymbionts, there was a trend toward worse initial visual acuity (P>0.05), central location (P<0.05), absence of radial perineuritis (P<0.05), delayed time to detection (P>0.05), and longer symptom duration at presentation (P>0.05).
Most Acanthamoeba isolates responsible for AK harbor 1 or more bacterial endosymbionts. The presence of endosymbionts enhances the corneal pathogenicity of Acanthamoeba isolates and may impact detection time and clinical features of AK.
确定从棘阿米巴角膜炎（AK）患者角膜和接触镜附属物中分离出的棘阿米巴分离株中是否存在 4 种临床相关的细菌内共生体，以及内共生体对 AK 发病机制的可能贡献。
实验研究。
从 23 例培养证实的 AK 患者的角膜和接触镜附属物中回收的棘阿米巴分离株（N=37）和 1 例环境分离株。
使用聚合酶链反应和序列分析、荧光原位杂交和透射电子显微镜等分子技术评估棘阿米巴分离株中属于军团菌属、假单胞菌属、分枝杆菌属和衣原体属的微生物内共生体的存在情况。使用体外人角膜上皮细胞细胞病变效应（CPE）测定法比较有和没有内共生体的棘阿米巴分离株的角膜毒性和毒力。对所有患者进行初始视力、浸润部位和特征、感染检测时间和就诊时症状持续时间的评估。
从 AK 中回收的棘阿米巴分离株中检测到的细菌内共生体的流行率和潜在病理生物学。
在检查的 38 个培养物中，有 22 个（59.4%）至少含有 1 种细菌内共生体。1 个分离株含有 2 种内共生体，即军团菌和衣原体，通过荧光原位杂交得到证实。与没有内共生体的分离株相比，含有棘阿米巴内共生体的分离株的角膜毒性（CPE）明显更高（P<0.05）。与军团菌相比，致病性角膜共生菌如假单胞菌和分枝杆菌显著增强了棘阿米巴的 CPE（P<0.05）。在存在细菌内共生体的情况下，初始视力（P>0.05）、中央位置（P<0.05）、无放射状神经周围炎（P<0.05）、检测时间延迟（P>0.05）和就诊时症状持续时间延长（P>0.05）的趋势更为明显。
大多数引起 AK 的棘阿米巴分离株都携带有 1 种或多种细菌内共生体。内共生体的存在增强了棘阿米巴分离株的角膜致病性，可能影响 AK 的检测时间和临床特征。
