Scanning Electron Microscopy and Molecular Biology Study of Staphylococcus Epidermidis Adhering to Intraocular Lenses

Abstract

Abstract: : Purpose: To study the morphological features of coagulase-negative staphylococci adherent to intraocular lenses by scanning electron microscopy and to determine whether the strain under study carried the intercellular adhesion (ica) locus, which encodes production of adhesins mediating adherence to biomaterials. Setting: Department of Ophthalmology, EA 3090, Edouard Herriot Hospital, Lyon, France. Methods: Sterile intraocular lenses (IOLs) were incubated in bacterial suspension (Staphylococcus epidermidis reference strain ATCC 14990) either for five minutes or for one hour. IOLs were then examined by scanning electron microscopy. In addition, polymerase chain reaction amplification was used to investigate whether the isolates under study carried the ica locus. Results: The bacteria appeared to be anchored to the surface of lenses by several different means, particularly "leg-like" processes and a slime layer, which likely came step by step into play. Polymerase chain reaction amplification revealed that S. epidermidis ATCC 14990 contained the ica locus. Conclusion: To our knowledge, for the first time in ophthalmology, photographs show these "leg-like" processes, involved in the first phase in adhesion, and visualize concretely the slime layer thanks to "embedded" bacteria. This study provided information about the nature and the genesis of these attachment processes. Adherence is known to be greater when the bacterial DNA contained the ica locus. A full knowledge of the pathogenesis of bacterial adhesion is necessary to better understand IOL infection and so endophthalmitis. None

Keywords: microbial pathogenesis: experimental studies • microscopy: electron microscopy • endophthalmitis