Biofilm modelling on the contact lenses and comparison of the in vitro activities of multipurpose lens solutions and antibiotics

Abstract

During the contact lens (CL) usage, microbial adhesion and biofilm formation are crucial threats for eye health due to the development of mature biofilms on CL surfaces associated with serious eye infections such as keratitis. For CL related eye infections, multi drug resistant Pseudomonas aeruginosa or Staphylococcus aureus (especially MRSA) and Candida albicans are the most common infectious bacteria and yeast, respectively. In this study, CL biofilm models were created by comparing them to reveal the differences on specific conditions. Then the anti-biofilm activities of some commercially available multipurpose CL solutions (MPSs) and antibiotic eye drops against mature biofilms of S. aureus, P. aeruginosa, and C. albicans standard and clinical strains were determined by the time killing curve (TKC) method at 6, 24 and 48 h. According to the biofilm formation models, the optimal biofilms occurred in a mixture of bovine serum albumin (20% v/v) and lysozyme (2 g/L) diluted in PBS at 37 °C for 24 h, without shaking. When we compared the CL types under the same conditions, the strongest biofilms according to their cell density, were formed on Pure Vision ≥ Softens 38 > Acuve 2 ∼ Softens Toric CLs. When we compared the used CLs with the new ones, a significant increase at the density of biofilms on the used CLs was observed. The most active MPS against P. aeruginosa and S. aureus biofilms at 24 h was Opti-Free followed by Bio-True and Renu according to the TKC analyses. In addition, the most active MPS against C. albicans was Renu followed by Opti-Free and Bio-True at 48 h. None of the MPSs showed 3 Log bactericidal/fungicidal activity, except for Opti-Free against S. aureus and P. aeruginosa biofilms during 6 h contact time. Moreover, all studied antibiotic eye drops were active against S. aureus and P. aeruginosa biofilms on CLs at 6 h and 24 h either directly or as 1/10 concentration, respectively. According to the results of the study, anti-biofilm activities of MPSs have changed depending on the chemical ingredients and contact times of MPSs, the type of infectious agent, and especially the CL type and usage time.

Retention, Bacterial Adhesion, and Biofilm Formation between Anionic and Zwitterionic Bandage Contact Lenses in Healthy Dogs: A Pilot Study

“…This study did not show significant differences in terms of in vivo bacterial adhesion between the two types of BCLs after short-term wear (24 h). The negatively charged BCL rapidly takes up lacrimal proteins, which create a suitable environment for microorganisms [ 13 , 14 , 15 , 18 ]. Among the lacrimal proteins, lysozyme, which is a positively charged antimicrobial enzyme, has been detected in high concentrations on BCLs and may be beneficial for preventing microbial adhesion during lens wear [ 14 , 18 ].…”

“…Fifty microliters of each cell suspension was plated onto the MSEY plates, and CFUs were counted after incubation at 37 °C for 18 h. The experiment was performed once using six A lenses and six B lenses for each of the four bacteria. The experimental conditions were designed based on previous reports [ 13 , 29 , 30 ] and validated in a preliminary study.…”

“…Mature biofilm development is associated with infections such as microbial keratitis, which can induce corneal opacity and melting corneal ulcers, leading to visual impairment [ 11 , 12 ]. When a BCL is placed on the cornea, it takes up proteins and other substances from the tear fluid, creating a suitable environment for microorganism growth [ 13 , 14 , 15 ]. Once planktonic bacteria adhere to the BCL, they form microcolonies or biofilms [ 13 , 14 , 15 , 16 , 17 ].…”

“…When a BCL is placed on the cornea, it takes up proteins and other substances from the tear fluid, creating a suitable environment for microorganism growth [ 13 , 14 , 15 ]. Once planktonic bacteria adhere to the BCL, they form microcolonies or biofilms [ 13 , 14 , 15 , 16 , 17 ]. Biofilm is a complex of microbial communities adhered to a surface and contained within exopolysaccharides, which protect bacteria from host defenses and/or antibiotics [ 13 , 16 , 17 ].…”

“…Once planktonic bacteria adhere to the BCL, they form microcolonies or biofilms [ 13 , 14 , 15 , 16 , 17 ]. Biofilm is a complex of microbial communities adhered to a surface and contained within exopolysaccharides, which protect bacteria from host defenses and/or antibiotics [ 13 , 16 , 17 ].…”