Detection of Biofilm Formation by Different Bacterial Isolates of Contact Lens

Abstract

Background: Biofilms are groups of microorganisms that collect to each other and with different surfaces by adherence mechanisms. These are formed of cells and extracellular matrix manufactured by these cells. There may be a great problem in some situations e.g. on medical implants and resistance against antibiotics. Objective: The objective of this study is to determine biofilm forming power of bacteria isolated from the conjunctiva, contact lens and the lens storage case by both phenotypic and genotypic detection methods. Methodology: Samples were taken from (36) persons in the period from January 2020 to June 2020 at Ophthalmology Department, Tanta University Hospitals, all the samples were transported to the Medical Microbiology & Immunology Department, Tanta University where bacterial strains were isolated. The biofilm formation phenotypic detection was performed by both tube method and Congo red agar method. The biofilm-forming genes of coagulase negative Staphylococcus (CoNS) and Staphylococcus aureus (ica A) and that of P. aeruginosa (psl A), were detected by PCR. Results: The (216) samples (swabs & discarded lenses) gave rise to a total number of (247) bacterial isolates. By using tube method; (52.3%) were moderately positive, (31.5%) strongly positive and (16.2%) negative for biofilm formation while after using the Congo red agar method; (35.3%) were moderately positive, (38.4%) strongly positive and (26.3%) negative for biofilm formation. Regarding the Staphylococcus aureus isolates, two (50%) of these were containing (icaA) gene. Regarding the (21) CoNS isolates, three (14.3%) contained (icaA) gene. Although all of the Pseudomonas isolates didn't contain pslA (1119 bp) gene, these were positive for biofilm production by phenotypic methods. Conclusion: The majority of the isolates had the capacity to form biofilms. Both tube and Congo red agar methods showed clear significant correlation and detected a high number of biofilm-producing strains. The absence of genes responsible for biofilm formation did not exclude the phenotypic biofilm production by these bacteria which is a common state.