Analysis of P. aeruginosa disinfectant sensitivity and microbial adhesions to worn cosmetic contact lenses

The role of Type III secretion system in the pathogenesis of Pseudomonas aeruginosa microbial keratitis

Pseudomonas aeruginosa is the most commonly isolated Gram-negative pathogen causing sight-threatening microbial keratitis (MK). Contact lens wear is the most significant risk factor associated with pseudomonal MK. Understanding the pathogenesis of MK due to P. aeruginosa and its interactions with contact lenses is crucial in preventing these often rapidly progressive and highly antibiotic-resistant infections. Bacterial virulence factor Type III secretion system (T3SS) has significant interplays between contact lens material, antibiotic sensitivity, disinfectant selectivity, and bacterial cell invasion. Depending on the T3SS exotoxins produced, P. aeruginosa strains are divided into cytotoxic or invasive strains. Cytotoxic strains are relatively resistant to commercial disinfectants, while invasive strains are more antibiotic resistant. Therefore, contact lens wearers are more predisposed to cytotoxic P. aeruginosa infections, and patients with trauma or previous surgery are more prone to infection by invasive strains. Previous studies with mutant P. aeruginosa strains unable to produce T3SS exotoxins were more susceptible to disinfectants and less able to adhere to soft contact lenses, indicating an essential role of T3SS in bacterial virulence. Invasion of P. aeruginosa intracellularly was found to be associated with control of scaffold protein IQ-domain GTPase-activating protein 1 (IQGAP1) and human corneal epithelial cell tight junctions. Knockdown of IQGAP1 strengthened tight junctions that prevented intracellular survival of invasive P. aeruginosa strains and enhanced corneal epithelial cell survival. These novel findings of the vital role of T3SS in the pathogenesis of pseudomonal MKs will provide new guidelines in both prevention and treatment of this common eye-blinding infection.

Cosmetic Contact Lens-Related Corneal Infections in Asia

PURPOSE

To explore demographics, disease characteristics, and wear habits in cosmetic contact lens (CL)-related corneal infections in Asia.

DESIGN

Prospective multicenter cross-sectional study.

METHODS

Cases of CL-related corneal infection presenting over a 12-month period were prospectively identified from 11 centers in 8 countries in Asia. Case demographics, clinical features, microbiology, and compliance characteristics were compared between wearers using CLs for cosmetic purposes and those using CLs for the correction of refractive errors.

RESULTS

Six hundred and ninety-four CL wearers with corneal infection presented: 204 cosmetic CL (29.4%) and 490 (70.6%) refractive CL wearers. Cosmetic CL infections comprised 7%-54% of cases across the region. Compared with noncosmetic CL wearers, cosmetic CLs wearers were significantly more likely to be female (90% vs 59%), young (aged <25, 68% vs 44%), and to have a shorter period of wear experience. Lenses worn by cosmetic CL wearers were more likely to be hydrogel materials and manufactured with the pigment located on the back surface of the CL. Presenting disease characteristics and visual outcomes were similar in both groups. Causative organisms were similar between the 2 groups; however, there was a higher rate of Acanthamoeba disease (9%) in cosmetic wearers, compared with refractive wearers (1%; P < .005).

CONCLUSIONS

Cosmetic CL infections represent a significant proportion of CL-related infections in Asia. Cosmetic CL users with corneal infections are generally young, female, and wearing hydrogel CLs. Internet supply, quality control, and regulation of the sale of these products provide significant challenges in managing this population of vulnerable wearers.