Microbiota and P. aeruginosa Genotype adhesion difference on Worn Cosmetic Contact Lenses (CL) with Comparison of Disinfectant Sensitivity

Abstract

Purpose: To analyze attached microbes found on worn cosmetic CL materials and compare difference in adhesion of two Type III secretion genotypes of P. aeruginosa. Disinfection ability of four disinfectants is compared between two genotypes.

Methods: Healthy volunteers with myopia < -6 D and astigmatism < -1.0 D with signed informed consent were recruited in this prospective randomized study. Subjects wore nelfilcon (Alcon Freshlook Colorblends gray), hilafilcon (Bausch & Lomb Naturelle black),or etafilcon (Johnson & Johnson Acuvue 2 Define Accent style black) daily disposable CL for at least 8 hours/day for 2 weeks. The lenses are collected aseptically. Half of the lens is used to identify attached microbes. The other half is incubated for 2 hrs with10⁸cfu/ml of cytotoxic PA103 or invasive PAK strains. Viable cell culturing was done to determine number of bacteria attached. P. aeruginosa incubated lenses were soaked with various disinfectants (Renu, Aosept, Puremoist, and Replenish) at 25%, 50%, 75%, and 100% of the suggested disinfection time. The number of bacteria remaining on CL is counted and compared.

Results: The most commonly identified microbes attached to non-symptomatic volunteers were coagulase negative Staphylococcus, P. aeruginosa, and Streptococci. Adhesion of the cytotoxic strain PA103 was found to be greatest for hilfilcon lenses (34.8x10⁴cfu/ml) > etafilcon (33.1 x10⁴cfu/ml) > nelfilcon (15.5x10⁴cfu/ml) (P<0.05; ANOVA). Similar trend is noted for adhesion of the invasive strain PAK: hilfilcon (30.9x10⁴ cfu/ml)>etafilcon(37.5x10⁴ cfu/ml) >nelfilcon(10.1x10⁴ cfu/ml) (P<0.05; ANOVA). At 100% suggested time, all tested disinfectants were able to kill all bacteria. However, at less than 75% of suggested disinfection time, significant number of viable cytotoxic P. aeruginosa remained (P=0.03, t-test).

Conclusions: With increasing popularity of cosmetic CL, clinicians are should be aware that different cosmetic materials attract different microbial adhesions. P. aeruginosa, a commonly identified pathogen in CL-associated microbial keratitis, is frequently found attached to CL of asymptomatic individuals. Cytotoxic strains are more resistant to MPS solution especially Renu. Proper lens care with strict adherence to suggested disinfection time is strongly advised to prevent sight threatening infections related to cosmetic lens wear.