Characterization of antibiotic resistance, biofilm formation ability and resistance to oxidative stress and halostress in isolates from contact lens cleaning solution (CLCS) and contact lens used by CLARE (Contact lenses associated red eye) patient. Trypticase soy peptone media was used for the microbiological isolation and maintenance. Antibiotic resistance was determined by using Kirby Bauer disk diffusion assay as per CLSI nomenclature. Biofilm formation assay was carried out by recommended techniques. In the present study, Enterobacter aerogenes CIN3, Burkholderia cepecia A2P1 and Proteus vulgaris B2P1 strains were isolated from CLCS used by CLARE patient. All three isolates were resistant to ampicillin, chloramphenicol, co-trimoxazole, colistin sulphate, streptomycin, sulfatriad, tetracycline and sensitive to ciprofloxacin and imipenem. B. cepecia and P. vulgaris also showed resistance to levofloxacin, norfloxacin and moxifloxacin. The multiple drug resistant isolates were characterized for their ability to form biofilms and produce exopolymeric substances implicated in the etiology of CLARE. In addition, biofilm formation of B. cepecia and P. vulgaris was induced by following exposure to oxidative (25 and 50 mM hydrogen peroxide) and salinity (5.0 and 9.5% NaCl) stress at antimicrobial concentrations typically found in CLCS. Only E. aerogenes growth reduced following treatment with oxidative and salinity stress. The importance of biofilm forming isolates in the pathogenesis of ocular infections mediated through usage of abiotic prosthetic devices such as contact lenses and contact lens cleaning solutions is emphasized.
