Comparison of Biofilm Formation Capacities of Two Clinical Isolates of Staphylococcus Epidermidis with and without icaA and icaD Genes on Intraocular Lenses

Abstract

Objectives: To compare biofilm formations of two Staphylococcus epidermidis (S. epidermidis) isolates with known biofilm formationcapacities on four different intraocular lenses (IOL) that have not been studied before.Materials and Methods: Two isolates obtained from ocular surfaces and identified in previous studies and stored at -86 °C in 15%glycerol in the microbiology laboratory of the Anadolu University Department of Biology were purified and used in the study. The isolateswere S. epidermidis KA 15.8 (ICA+), a known biofilm producer isolate positive for icaA, icaD and bap genes, and S. epidermidis KA 14.5 (ICA-),known as a non-biofilm producer isolate negative for icaA, icaD and bap genes. The biofilm formation capacities of the 2 isolates on 4 differentIOLs were compared. Two of the IOLs were acrylic (UD613 [IOL A], Turkey; SA60AT [IOL B], USA), and the other two were polymethylmethacrylate (PMMA) (B60130C [IOL C], India; B55125C [IOL D], India). Bacterial enumeration and optical density measurements weredone from biofilms that formed on the IOLs. Biofilms were imaged using scanning electron microscopy.Results: Mean bacterial counts on the IOLs were 7.1±0.4 log10 CFU/mL with the ICA+ isolate, and 6.7±0.8 log10 CFU/mL with theICA- isolate; there were no statistically significant differences. Biofilm formation was lower with acrylic lenses than PMMA lenses withboth isolates (p=0.009 and p=0.013). The highest biofilm production was obtained on IOL C (PMMA) (p