Risk Factors for Contact Lens Bacterial Contamination During Continuous Wear

Abstract

Purpose Microbial contamination of contact lenses is associated with corneal infection and inflammation. This study determined which microbiological, clinical and demographic factors are associated with bacterial contamination of a silicone hydrogel contact lens when worn for continuous wear. Methods Two hundred five normal subjects were enrolled in the Longitudinal Analysis of Silicone Hydrogel (LASH) Contact Lens Study and were fitted with lotrafilcon A lenses for monthly continuous wear and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline, and after 1 week and 4 months of continuous wear. Lenses and ocular sites were considered to have substantial microbial bioburden when they harbored pathogenic organisms or high levels of commensal organisms. Univariate and multivariate logistic regression analyses were conducted to examine whether substantial conjunctival or lid bioburden, subject demographics, lens wearing history, symptoms, and biomicroscopic signs were associated with lens bioburden. Results About one-third (32.4%) of subjects had substantial bacterial bioburden in either eye across multiple visits. Over half (53.2%) and about one-tenth (11.7%) of subjects had substantial lid and conjunctival bioburden, respectively, and 11.2% discontinued due to discomfort. The adjusted odds ratios (and 95% confidence intervals) for presence of substantial lens bioburden were 2.49 (1.17–5.30), 4.24 (1.45–12.40), and 4.11 (1.17–14.46) for substantial lid bioburden, substantial conjunctival bioburden, and lens discomfort, respectively. Conclusions Bacterial contamination of silicone hydrogel contact lenses is common during continuous wear. Substantial lens bioburden is associated with discomfort precluding successful continuous wear. The presence of substantial lid and conjunctival bioburden are associated with a 2.5 fold and over 4 fold greater risk of substantial lens bioburden and are likely the major routes of contamination.

Bacterial Biofilm Diversity in Contact Lens-Related Disease: Emerging Role ofAchromobacter,Stenotrophomonas, andDelftia

“…The converse of this relationship is that limited bacterial diversity will be detected in non-disease continuous wear lenses, as was reported previously. 11 Based on our findings, and consistent with other biofilm infections, the severity of contact lens-related disease is predicted to increase with bacterial diversity. This notion is of clinical importance because infections caused by multiple bacterial species are problematic to treat.…”

Case-Control Pilot Study of Soft Contact Lens Wearers With Corneal Infiltrative Events and Healthy Controls

“…22,54 As shown by other groups, significant levels of gram-negative bacteria were more common in subjects with active CIEs compared to healthy controls. 21,22,24,54 It is noteworthy that, while culturing is not the standard of care for CIEs considered to be low risk for MK, this study revealed that even mild to moderate case presentations harbored gram-negative bacteria known to be resistant to standard treatment regimens (e.g., Achromobacter xylosoxidans and Elizabethkingia and Delftia spp). 21,55 Consistent with previous findings, the bacteria identified on the majority of the healthy control subjects were normal commensal flora below our specified levels of substantial bioburden.…”

Detection of Biofilm Forming Ability of Bacterial Isolates from Contact Lenses and their Accessories

“…22 contact lens accessories samples were subjected to bacteriological analysis. Following bacterial isolates were isolated from the samples (Tables 1-4 Lens contamination is probably the greatest risk factor for corneal infection, the sources and factors leading to the contamination of microbes on lenses are of great interest [9]. Table 3: Isolation from contact lenses.…”

“…According to Loretta [9] the most likely route for contamination of contact lenses is from the skin to the lens. The evidence for this is that the majority of isolates found on contact lenses in their study were coagulase negative staphylococci which are normal, ubiquitous skin microbiota but in our study only 1 coagulase negative Staphylococci was isolated.…”