Bacterial isolates and their biofilm formation on contact lenses

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Using contact lenses without proper care and sterilization measures can lead to eye infection like keratitis and other eye diseases. About 25-30% of cases with corneal ulcers are related to contacts lens use. Microbial agents after their entry, they further invade into corneal layers by their virulence factors and enzymatics secreted by the bacteria. Wearing contact lenses also increase stress on cornea so the cornea has less ability to defend against the bacteria which is invading. Some of the bacteria are also capable of biofilm formation. Biofilms formed on contact lens surfaces has increased resistance to common steriliants used in contact lens care solution. The main aim of this study is to identify the pathogens that can be grown on the contact lenses and contact lens cases, to identify the production of biofilm by the isolates obtained during this study and to bring awareness about proper sterilization of contact lenses and lens cases during their usage to prevent unnecessary eye infections. This cross sectional study was carried from October 2019 to June 2021 on MBBS and BDS students in Konaseema Institute of Medical Sciences and Research Foundation, who are using contact lenses and who are asymptomatic. Written consent from all students participating in this study was taken. The samples are collected using sterile swabs. Swabs from both the lens and lens cases are taken and immediately cultured and related biochemical tests are done to identify the organism. For the study of biofilm formation, the bacterial isolates obtained from the specimen are inoculated on to commercially available Congo red agar (CRA). The data was processed and arranged into distribution tables and cross tables using statistical package for the social sciences (SPSS) version 21. Total 200 samples were collected and processed for bacterial culture. Among them 145(72.5%) samples showed positive bacterial culures. The most common organisms obtained are which were 30 (20.6%), next common organism isolated were micrococci 24(16.5%), though ASB’s and micrococci are non pathogenic, these were included because the lens and lens cases are preferably to be sterile. The other organisms isolated are 21 (14.4%), 18 (12.4%), 16 (11.04%), 12 (8.2%), 10 (6.9%), 8 (5.5%) and 6 (4.2%). The isolated bacteria are then again streaked on Congo Red Agar to check for the ability of the bacterial isolates to form biofilms. Among 145 bacterial isolates obtained in this study 98 (67.5%) samples showed positive biofilm formation. The micro organisms can lodge in most of the contact lenses and contact lens cases… which in turn enter into eye due to improper sterilization of lens and lens cases. And most of the bacterial isolates obtained from these contact lenses and contact lens cases are capable of production of biofilm. To avoid infections caused by contact lens users the care of both the contact lenses and lens cases is very important.