Bacterial lipases and chronic blepharitis

Abstract

Eyelids and conjunctivae of 36 normal individuals and 60 patients from six clinical groups of chronic blepharitis were cultured for aerobic and anaerobic bacteria. The most common species isolated were coagulase-negative staphylococci (C-NS) and Propionibacterium acnes. All strains of these species, and all Staphylococcus aureus strains isolated were tested for the ability to break down triglycerides, cholesterol esters, and fatty waxes. Each strain was incubated independently with appropriate substrates in nutrient media. Each medium was then extracted and assayed for the presence of substrate hydrolysis products by thin-layer chromatography. The percentage of strains capable of hydrolyzing a particular substrate was determined for each individual. S. aureus was a consistent and strong lipase producer, able to hydrolyze all three substrates. P. acnes was able to hydrolyze triolein and behenyl oleate but not cholesteryl oleate. No differences were observed among groups for P. acnes or S. aureus. C-NS showed a high degree of strain variability. Eighty-three percent of C-NS strains could hydrolyze triolein, 82% behenyl oleate, and 40% cholesteryl oleate. Significant group differences were seen in the percentage of lipase positive C-NS strains isolated per individual. Patients in the mixed staphylococcal/seborrheic, meibomian seborrheic, secondary meibomitis, and the meibomian keratoconjunctivitis (MKC) groups harbored significantly more C-NS strains capable of hydrolyzing cholesteryl oleate than did normal individuals. Patients in the meibomian seborrheic, secondary meibomitis, and MKC groups harbored significantly more C-NS strains capable of hydrolyzing behenyl oleate than did normals. No group differences were seen among groups with triolein hydrolyzing C-NS strains.