Pseudomonas aeruginosa Survival at Posterior Contact Lens Surfaces after Daily Wear

Abstract

Purpose Pseudomonas aeruginosa keratitis is a sight-threatening complication of contact lens wear, yet mechanisms by which lenses predispose to infection remain unclear. Here, we tested the hypothesis that tear fluid at the posterior contact lens surface can lose antimicrobial activity over time during lens wear. Methods Daily disposable lenses were worn for 1, 2, 4, 6 or 8 h immediately after removal from their packaging, or after presoaking in sterile saline for 2 days to remove packaging solution. Unworn lenses were also tested, some coated in tears “aged” in vitro for 1 or 8 h. Lenses were placed anterior surface down into tryptic soy agar cradles containing gentamicin (100µg/ml) to kill bacteria already on the lens, and posterior surfaces inoculated with gentamicin-resistant P. aeruginosa for 3 h. Surviving bacteria were enumerated by viable counts of lens homogenates. Results Posterior surfaces of lenses worn by patients for 8 h supported more P. aeruginosa growth than lenses worn for only 1 h, if lenses were presoaked prior to wear (~ 2.4-fold, p = 0.01). This increase was offset if lenses were not presoaked to remove packaging solution (p = 0.04 at 2 h and 4 h). Irrespective of presoaking, lenses worn for 8 h showed more growth on their posterior surface than unworn lenses coated with tear fluid that was “aged” for 8 h vitro (~8.6-fold, presoaked, p = 0.003: ~ 5.4-fold from packaging solution, p = 0.004). Indeed, in vitro incubation did not impact tear antimicrobial activity. Conclusions This study shows that post lens tear fluid can lose antimicrobial activity over time during contact lens wear, supporting the idea that efficient tear exchange under a lens is critical for homeostasis. Additional studies are needed to determine applicability to other lens types, wearing modalities, and relevance to contact lens-related infections.

Mucosal fluid glycoprotein DMBT1 suppresses twitching motility and virulence of the opportunistic pathogen Pseudomonas aeruginosa

“…Of likely relevance to the pathogenesis of contact lens related infections, when a contact lens is worn it dramatically reduces normal tear exchange between the greater tear fluid reservoir and the space between the lens and ocular surface [ 9 , 10 ]. Suggesting that tear fluid biochemistry is altered under a worn lens, and that this is potentially relevant to the pathogenesis of infection, bacteria inoculated on the back surface of worn lenses grew more efficiently after 8 h of wear compared to 1 h of wear [ 11 ]. Candidate antimicrobial tear components in tear fluid that could be impacted by lens wear include; complement, defensins, lactoferrin, lipocalin, lysozyme, secretory phospholipase A2, secretory IgA, soluble mucins (Muc5AC), and/or surfactant proteins (SP-A, SP-D) [ 12 ].…”

Practice and Knowledge of Contact Lens Use Among Medical Students of Universiti Teknologi MARA

“…P. aeruginosa has also been shown to form biofilms on the posterior surface of the lens. Besides, over time during contact lens use, posterior lens tear fluid can lose antimicrobial activity, thus increasing the risk of microbial keratitis (Wu, Zhu, Tam, Evans, & Fleiszig, 2015).…”

Bacterial Pathogens Associated With Eyeglasses and Risks of Infection among Staff and Students of a Private University in South–West Nigeria

“…Daily, whether in the market, schools, churches, the comfort of our homes, or even in our offices, we are unknowingly exposed to many pathogens [5]. Unfortunately, many frequently used devices, such as eyeglasses and contact lenses, are rarely sterilized or kept clean, which increases the likelihood of bacterial contamination and colonization [6,7].…”