Slime production by coagulase-negative staphylococci isolated in chronic blepharitis

Background. The purpose of the study was to determine the impact of slime-producing strains of coagulase-negative staphylococci (CNS) on non-ulcerative blepharitis. Formerly considered harmless organisms, CNS are now recognised as opportunistic pathogens. Although these microorganisms are a component of normal conjunctival flora, they often produce the typical signs and symptoms of chronic staphylococcal blepharoconjunctivitis. Certain strains produce a polysaccharide extracellular material called "slime". Slime production is considered to be associated with the virulence of the organism. Methods. Swabs were taken from the lids of 38 eyes of 19 patients with chronic non-ulcerative blepharitis and cultured for CNS. A group of 42 normal control eyes were similarly sampled. The strains of CNS isolated from 26 eyes (68.4%) of the patients with blepharitis and 25 eyes (59.5%) of the normal subjects were studied for slime layer production. Results. No significant difference was found between normal subjects and patients in the incidence of slime producing CNS strains from the conjunctiva. The antibiotic sensitivity profiles of the slime-producing strains were no different from the slime-negative isolates in the blepharitis (p=0.85) and normal group (p=0.25). Conclusions. Our data suggest that slime production by CNS does not play a significant role in the pathogenesis of staphylococcal blepharitis.