Purpose. To study the efficacy of topical versus intrastromal administration of penicillin G in the treatment of experimental Streptococcus viridans crystalline keratopathy in a rabbit model. To assess whether the intrastromal route of administration of antibiotic offers any advantage in overcoming the resistance conferred by the exopolypeptide glycocalyx of Streptococcus viridans. Methods. 106 colony forming units of a strain of penicillin-sensitive Streptococcus viridans obtained from a patient with clinically proven infectious crystalline keratopathy were inoculated intrastromally into 20 corneas of 20 NZW rabbits. After 72 hours, all inoculated corneas developed crystalline keratopathy. The eyes were then randomly allocated to 4 treatment protocols (n=5 each) : 1) Hourly topical penicillin G (100,000 IU/ml), 2) Single intrastromal injection of penicillin G (1,000 IU/ml), 3) Hourly topical normal saline, 4) Single intrastromal injection of normal saline. After 12 hours, the animals were sacrificed and their corneas harvested, emulsified, plated onto culture media and incubated at 35°C for subsequent quantitative bacteriological analysis. Results. In eyes treated with penicillin G, there was no statistically significant difference in colony counts between eyes treated topically and eyes treated intrastromally (p > 0.05). There was also no significant difference in colony counts between penicillin G treated eyes and control eyes (p > 0.05). Conclusion. This study demonstrates the in-vivo resistance of the crystalline keratopathy producing Streptococcus viridans to both topical and intrastromal penicillin, despite its in-vitro sensitivity. Intrastromal delivery of antibiotic demonstrated no advantage over conventional topical therapy.
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
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