The effectiveness of a topical antibiotic irrigating solution in a model of staphylococcal keratitis after lamellar keratectomy.

PURPOSE: To create a model of Staphylococcus aureus keratitis after lamellar keratectomy; to assess the toxicity of an antibiotic irrigating solution on the corneal stromal bed; and to test the chemotherapeutic effectiveness of a topical antibiotic, both alone and with an antibiotic-containing irrigating solution in preventing S. aureus keratitis after lamellar keratectomy. METHODS: The right eye of each of 38 rabbits were used in this study. In 18 eyes, a lamellar flap was created with a microkeratome, and an inoculum of S. aureus (either 1,000, 5,000, or 50,000 CFUs) was instilled under each flap; the eyes were examined for signs of infection and inflammation at 24 and 48 hours. In another five eyes, a lamellar flap was created in the same manner and the stromal bed was irrigated with 0.3% ofloxacin; the eyes were assessed for ocular inflammatory changes and evidence of crystalline deposits. Finally, in each of 15 additional eyes, 1,000 CFUs of S. aureus were instilled under a lamellar flap to create experimental infectious keratitis. The keratitis was treated according to three regimens: irrigation of the stromal bed with sterile balanced salt solution; irrigation of the stromal bed with 0.3% ofloxacin, followed by application of topical ofloxacin four times a day; application of topical ofloxacin only, four times a day. Eyes were examined for infection and ocular inflammatory changes at 24 and 48 hours. RESULTS: Staphylococcus aureus keratitis can consistently be produced under the stromal flap by inoculation of relatively few organisms. Irrigation of the stromal bed with commercial-strength topical ofloxacin does not appear to be toxic to the stromal bed, with no evidence of crystalline precipitates of the antibiotic. In our model of infectious keratitis after lamellar keratectomy, both topical ofloxacin alone and the combination of topical ofloxacin and irrigation of the stromal bed with 0.3% ofloxacin were effective at preventing S. aureus keratitis. However, the combined treatment of antibiotic irrigation plus topical antibiotic was more effective at preventing inflammation than topical ofloxacin alone. CONCLUSIONS: In this model of S. aureus keratitis after lamellar keratectomy, irrigation of the stromal bed with antibiotic plus topical antibiotic appears to be both safe and effective for preventing infection.

The importance of initial management in the treatment of severe infectious corneal ulcers.

PURPOSE: To identify factors that influence the outcome of patients with severe infectious corneal ulcers. METHOD: A retrospective review was performed of the hospital records of all such patients admitted to the Doheny Eye Hospital during a 30 month period. Outcome variables examined were change in visual acuity, duration of hospitalization, hospital charges, and percentage of patients who required penetrating keratoplasty. RESULTS: Sixty-two ulcers were included. An organism was identified and antibiotic sensitivities established in 52 patients (84%). Inpatient therapy involved a combination of fortified aminoglycoside and cephalosporin antibiotics in 39 patients (63%) and was found to be appropriate on the basis of sensitivity studies in 49 (94%) of 52 patients. Inappropriate initial treatment was related to increased hospital charge (P = 0.024) as well as increased risk of penetrating keratoplasty (P = 0.001). CONCLUSIONS: Appropriate initial therapy is most critical in the course of serious corneal ulcers, and aggressive, broad-spectrum antibiotic coverage is advocated.