IN-VITRO STAPHYLOCOCCUS-EPIDERMIDIS GROWTH IN SOME VISCOELASTIC SUBSTANCES CONTAINING SODIUM HYALURONATE

The aim of our study was to verify the in vitro growth of Staphylococc us epidermidis in various dilutions of some viscoelastic substances co ntaining hyaluronic acid (Healon(R) and Healon GV, IAL(R), Biolon(TM)) . Serial twofold dilutions of each sterile viscoelastic substance, pre pared so as to obtain a final concentration ranging from 50 to 0.78% o f the product in sterile saline solution (0.85% NaCl), were taken out with a pipette that delivered 1.0 ml/tube. One hundred microliters of the S. epidermidis inocula, used for the evaluation of the positive co ntrol of the test organism, was dispensed into each tube. After 24 h o f aerobic incubation at 37 degrees C, 100 mu l of sample was taken out from each tube and plated into the specific medium for the growth of the test organism. After 24 h of incubation at 37 degrees C, these aga r plates were examined and the colony-forming unit count of the test o rganism was compared to the corresponding total colony count, acting a s a positive control, in order to determine the quantitative variation of the test organism grown in the presence of the viscoelastic compou nds. For the lowest dilutions (from 1:2 to 1:8) statistically signific ant bacterial growth was detected in all tested viscoelastic substance s. For the highest dilutions (1:64 and 1:128) Biolon and Healon GV sho wed a significant inhibition of S. epidermidis growth. A significant i nhibition was also observed in the highest dilution (1:128) of Healon. In every dilution of IAL a statistically significant increase in bact erial growth was observed. It remains to be carefully considered wheth er S. epidermidis, accidentally penetrating the eye via the intraocula r lens, could find a culture medium in a small amount of sodium hyalur onate left in the capsular bag behind the optic.