Journal of Clinical and Experimental Ophthalmology
Open Access

Abstract

Biofilm: The Haven for Staphylococcus epidermidis in Post-operative Endophthalmitis

Sujata Prasad, Niranjan Nayak, Gita Satpathy, Tapas Chandra Nag, Pradeep Venkatesh and Ravinder Mohan Pandey

Background: Staphylococcus epidermidis, in spite of being a commensal of the eye, is regarded as one of the common etiological agents of bacterial endophthalmitis. The purpose of the study was to determine the pathogenic potential of this commensal organism in post-operative endophthalmitis.
Methods: A total of 63 S epidermidids isolates, comprising of 47 from vitreous samples of post-operative endophthalmitis cases and 16 controls from the healthy conjunctivae, were studied. Biofilm producing ability was determined by quantitative adherence test and "ica AB" Polymerase Chain Reaction (PCR) assay. Bacteria adhering onto the lens surfaces were enumerated by standard protocol. Scanning electron microscopy (SEM) was employed to visualize the biofilms on the lenses.
Results: Of the 47 isolates, 23 (48.9%) were adherent and 24 (51.0%) were nonadherent. PCR showed that 16 (34.0%) isolates possessed the ica locus whereas 31 (65.9%) did not possess this gene. All 16 (100%) ica positive organisms and only 7 (22.58%) of the 31 ica negative organisms adhered to artificial surfaces (p<0.001). SEM revealed that isolates carrying ica gene had formed intimate biofilms on intra ocular lenses. Clinical isolates showed significantly higher number of attaching bacteria onto the lens material as compared to the commensals.
Conclusions: This study documented that bacteria carrying ica gene were found to be adherent and biofilm producers. Biofilm could be incriminated as a virulence marker for S epidermidis causing post-operative endophthalmitis. PCR was a sensitive and rapid tool to detect biofilm forming ability.