Purpose: The aim of this study was to analyze patient data and the laboratory results of corneal samples collected from patients followed at the Ophthalmology Department, Hospital São Paulo, Brazil over a 30-year period, and correlate the analize with contact lens wearing.
Methods: Corneal samples from patients diagnosed clinically with microbial keratitis between January 1987 and December 2016 were included in this study. Cultures that were positive for bacteria, fungi, and Acanthamoeba spp. were analyzed retrospectively. To ascertain if the number of patients with contact-lens-associated microbial keratitis (as a risk factor for microbial infection) changed over time, the analysis was divided into three decades: 1987-1996, 1997-2006, and 2007-2016. Information pertaining to patient gender and age, as well as type of organism isolated, were compared among these periods.
Results: The corneal samples of 10.562 patients with a clinical diagnosis of microbial keratitis were included in the study, among which 1.848 cases were related to the use of contact lenses. The results revealed that the frequency of contact-lens-associated microbial keratitis increased over the last two decades. Overall, females had contact-lens-associated microbial keratitis more frequently (59.5%). Patients aged 19-40 years also had contact-lens-associated microbial keratitis more frequently in all study periods. Staphylococcus spp. and Pseudomonas spp. were the most frequent Gram-positive and Gram-negative bacteria, respectively, in the microbial keratitis groups. Among the fungal cases of microbial keratitis, filamentous fungi were the most frequent fungi over the entire study period, with Fusarium spp. being the most frequent fungi in the group with microbial keratitis not associated with contact lens wearing (p<0.001). Samples positive for Acanthamoeba spp. and Pseudomonas spp. were significantly correlated with contact-lens-associated microbial keratitis (p<0.001).
Conclusions: Females and young adults aged 19-40 years exhibited the highest frequency of contact-lens-associated microbial keratitis in our study. Staphylococcus spp. and Fusarium spp. were the predominant bacteria and fungi, respectively, isolated from corneal samples. Pseudomonas spp. and Acanthamoeba spp. were significantly correlated with contact-lens-associated microbial keratitis in this study.