Modified tissue culture medium for corneal storage. II. Investigation of the effect of the corneoscleral rim on bacterial contamination.

Our previous experiments showed the effect of time, temperature, and antibiotics on replication of Staphylococcus epidermidis and Pseudomonas aeruginosa introduced into the modified tissue culture medium (MTCM). Penicillin G potassium was ineffective in the MTCM, and gentamicin sulfate was not uniformly effective against a gentamicin-sensitive organism. Placement of the MTCM at room temperature for two hours enhanced the antibacterial activity of gentamicin. Culturing techniques that fail to remove the antibiotic from the system are invalid. Experiments reported herein showed that the addition of the corneoscleral rim (or extraneous protein) prolongs the survival of these same organisms. Organisms can survive in the MTCM despite high concentrations of gentamicin. Maintaining the MTCM at room temperature for two hours after storage at 4 degrees C effectively reduces but may not completely eliminate the recovery of organisms. The antibiotic removal device may be superior to other methods for recovering viable organisms.