Incidence of contact-lens-associated microbial keratitis and its related morbidity
ABSTRACT The incidence of contact-lens-associated microbial keratitis is uncertain and its related morbidity in the general population of contact-lens wearers is not known. We examined these issues in a prospective epidemiological study.
We surveyed all practising ophthalmologists in the Netherlands to identify all new cases of microbial keratitis reported during a 3-month period in 1996. Follow-up telephone calls were made to examine ocular morbidity. We undertook annual nationwide telephone surveys between 1994 and 1997 to estimate the prevalence of contact-lens wear.
Of 440 ophthalmologists contacted, 379 provided information. There were 92 cases of microbial keratitis; 17 used daily-wear rigid gas-permeable lenses, 63 daily-wear soft lenses, and 12 extended-wear soft lenses. The estimated annualised incidence of microbial keratitis was 1.1 per 10,000 (95% CI 0.6-1.7) users of daily-wear rigid gas-permeable lenses, 3.5 per 10,000 (2.7-4.5) users of daily-wear soft lenses, and 20.0 per 10,000 (10.3-35.0) users of extended-wear soft lenses (p<0.00001 for comparison between all groups), Five of the 92 patients achieved a final visual acuity of 20/70 or less. Pseudomonas and Serratia spp were the organisms most commonly isolated. Pseudomonas keratitis accounted for the largest mean diameter of corneal ulcers, the highest mean number of days in hospital, the greatest number of mean outpatients visits, and the poorest visual acuity outcome.
The incidence of microbial keratitis among users of extended-wear soft contact lenses in the Netherlands is similar to that reported in the USA during 1989. Awareness of risk factors and improvement in contact-lens materials have not led to a decrease in incidence. Overnight wear should be strongly discouraged.
SourceAvailable from: Eric Tzyy-Jiann Chong
Dataset: 1136 42
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ABSTRACT: The opportunistic pathogen Pseudomonas aeruginosa can infect almost any site in the body but most often targets epithelial cell-lined tissues such as the airways, skin, and the cornea of the eye. A common predisposing factor is cystic fibrosis (CF), caused by defects in the cystic fibrosis transmembrane-conductance regulator (CFTR). Previously, we showed that when P. aeruginosa enters epithelial cells it replicates intracellularly and occupies plasma membrane blebs. This phenotype is dependent on the type 3 secretion system (T3SS) effector ExoS, shown by others to induce host cell apoptosis. Here, we examined mechanisms for P. aeruginosa-induced bleb formation, focusing on its relationship to apoptosis and the CFTR. The data showed that P. aeruginosa-induced blebbing in epithelial cells is independent of actin contraction and is inhibited by hyperosmotic media (400 to 600 mOsM), distinguishing bacterially induced blebs from apoptotic blebs. Cells with defective CFTR displayed enhanced bleb formation upon infection, as demonstrated using bronchial epithelial cells from a patient with cystic fibrosis and a CFTR inhibitor, CFTR(Inh)-172. The defect was found to be correctable either by incubation in hyperosmotic media or by complementation with CFTR (pGFP-CFTR), suggesting that the osmoregulatory function of CFTR counters P. aeruginosa-induced bleb-niche formation. Accordingly, and despite their reduced capacity for bacterial internalization, CFTR-deficient cells showed greater bacterial occupation of blebs and enhanced intracellular replication. Together, these data suggest that P. aeruginosa bleb niches are distinct from apoptotic blebs, are driven by osmotic forces countered by CFTR, and could provide a novel mechanism for bacterial persistence in the host.mBio 02/2015; 6(2). DOI:10.1128/mBio.02533-14 · 6.88 Impact Factor
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ABSTRACT: Microbial keratitis is affecting approximately 4 to 5 per 10000 contact lens wearers worldwide and the seriousness of the disease is depends on type of microbial species contaminated on the contact lens. As number of contact lens wearer is increasing globally including Malaysia in the past ten years, there is a need to identify the type of microbial species that contaminated on contact lenses among Malaysian especially in college students. Therefore, this study was conducted to evaluate the microbial contamination on contact lenses among university students and the habit of the contact lens wearer within the university facility. A total of 67 pairs of used contact lens samples were collected. CFU/ml was calculated based on colonies growth on nutrient agar to represent the microbial population density and Gram staining was performed for all pure cultures with different morphologies. Two major groups of contaminant with different morphologies were subjected for identification using biochemical tests. Our results suggested that 41.79% of the samples collected were contaminated with microbial and the contamination status was significantly different in gender and duration of contact lens wearing per usage (p < 0.05). Besides, monthly disposable contact lens had the highest contamination rate with mean of 2410 CFU/ml when compared to daily and quarter-yearly (3 months) contact lenses. The Gram staining showed that 88.47% of microbial contamination was Gram negative mainly presented with Vibrio spp. and Aeromonas spp. Our study unexpectedly found that contact lenses among university students were contaminated with microbials that might be found in the tap water they used to wash their hands.