Purpose

Biofilm formation caused by infrequent contact lens case replacement and the ineffectiveness of multi-purpose solutions (MPS) on biofilm removal is associated with high rates of bacterial keratitis infections. This study demonstrated biofilm elimination from the contact lens case by microwave irradiation.

Methods

Staphylococcus aureus biofilms indicative of 3–9 months of contact wear were cultured in contact lens cases and visualized with crystal violet (CV) staining. Biofilms in contact cases were then exposed to four treatment regimens: No treatment (n = 8), 45 s microwave irradiation (n = 8), tap water (n = 6), and MPS (n = 9). Bacterial survival was assessed by colony forming unit (CFU) assay using streak dilutions.

Results

Visualization of the biofilms through CV staining revealed that biofilms coalesce between ribs of the contact case. In 5/8 cases no CFU were cultivated from the case after treatment with microwave irradiation. In tap water and MPS the first dilution averaged 6 ± 2 and 31 ± 13 CFUs per plate, respectively, while microwave irradiation averaged < 1 CFU per plate. In Dilution 2, the average reduced to 0.7 ± 0.7 and 6 ± 5 CFUs per plate for tap water and MPS, respectively, while microwave irradiation had 0 CFUs in Dilution 2.

Conclusion

Biofilms that coalesce between the ribs of the contact case pose a threat because this area is difficult to thoroughly scrub and could act as a basis for infection through fouling of contact lenses. Of the four treatment regimens, microwave irradiation displayed the most consistent and highest rate of bacterial eradication. Tap water was less effective compared to microwave irradiation, and poses other harmful side effects, but greatly reduced CFU count compared to no treatment. MPS displayed the poorest bacterial eradication of the treatments. Thus, microwave irradiation is worth further investigation as a viable in-home disinfecting option.

中文翻译：

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探索微波辐照作为隐形眼镜盒消毒的方法

目的

由不经常更换隐形眼镜盒引起的生物膜形成和多用途溶液 (MPS) 对生物膜去除的无效与细菌性角膜炎感染率高有关。这项研究证明了通过微波照射从隐形眼镜盒中消除生物膜。

方法

在隐形眼镜盒中培养指示 3-9 个月接触磨损的金黄色葡萄球菌生物膜，并用结晶紫 (CV) 染色进行可视化。然后将接触病例中的生物膜暴露于四种治疗方案：不治疗 (n = 8)、45 秒微波照射 (n = 8)、自来水 (n = 6) 和 MPS (n = 9)。通过使用条纹稀释的菌落形成单位 (CFU) 测定来评估细菌存活率。

结果

通过 CV 染色对生物膜的可视化显示，生物膜在接触病例的肋骨之间结合。5/8例经微波照射后未培养出CFU。在自来水和 MPS 中，第一次稀释平均每板分别为 6 ± 2 和 31 ± 13 CFU，而微波辐射平均每板 < 1 CFU。在稀释 2 中，自来水和 MPS 的平均值分别降低到每板 0.7 ± 0.7 和 6 ± 5 CFU，而微波照射在稀释 2 中为 0 CFU。

结论

接触盒肋骨之间聚结的生物膜构成威胁，因为该区域难以彻底擦洗，并且可能通过污染隐形眼镜成为感染的基础。在四种治疗方案中，微波照射显示出最一致和最高的细菌根除率。与微波照射相比，自来水的效果较差，并且会产生其他有害的副作用，但与未处理相比，CFU 计数会大大降低。MPS 显示出治疗中最差的细菌根除。因此，微波辐照作为一种可行的家庭消毒选择值得进一步研究。