Abstract
Purpose :
Although part of periocular normal flora, coagulase-negative staphylococci (CNS) are frequent opportunistic pathogens after ocular surgery that cause endophthalmitis. CNS is generally not identified to the species level from eye cultures, but some species may be more common than others. The goal of the current study was to evaluate three methods of species level identification (Biolog GEN III, API Staph Ident, DNA sequencing) of CNS isolated from cases of endophthalmitis and determine whether they are in agreement with their identification of staphylococcal species that cause endophthalmitis.
Methods :
We compared the identifications of 47 isolates of CNS from endophthalmitis from the Charles T. Campbell Ophthalmic Microbiology Laboratory using Biolog GEN III Microplates, (phenotypic substrate system) (Hayward, CA), API Staph IDENT (biochemical system) (bioMerieux, USA), and DNA sequencing of the sodA gene. Sample preparation followed the standardized procedures for each test.
Results :
The identification of CNS to the species level were identical for Biolog and DNA sequencing except for 1 isolate. Of the 47 isolates for Biolog, 42 were Staphylococcus epidermidis, 3 were Staphylococcus lugdunensis, 1 was Staphylococcus hominis, and 1 was Staphylococcus haemolyticus. For DNA sequencing, 43 isolates were S. epidermidis, 2 were S. lugdunensis, 1 was S. hominis, and 1 was S. haemolyticus. Species identification differed for API Staph IDENT by 6 isolates compared to DNA sequencing and by 5 isolates compared to Biolog. Of the 47 isolates, 40 were S. epidermidis, 2 were S. lugdunensis, 2 were S. hominis, 1 was Staphylococcus capitis, 1 was S. haemolyticus, and 1 was Staphylococcus aureus (a possible weak producer of protein B?).
Conclusions :
CNS identification to the species level by all three methods indicated that S. epidermidis is the predominant species of CNS isolated from cases of endophthalmitis. Identification of CNS from keratitis, conjunctivitis, and blepharitis may indicate different distributions of CNS species.
This is a 2021 ARVO Annual Meeting abstract.