The Utility of Repeat Culture in Fungal Corneal Ulcer Management: A Secondary Analysis of the MUTT-I Randomized Clinical Trial

Abstract

Purpose To determine whether patients who had a positive repeated culture was predictive of worse clinical outcome than those who achieved microbiological cure at 6 days in the Mycotic Ulcer Treatment Trial I (MUTT-I). Design Secondary analysis from a multicenter, double-masked, randomized clinical trial. Methods SETTING: Multiple hospital sites of the Aravind Eye Care System, India. STUDY POPULATION: Patients with culture-positive filamentous fungal ulcers and visual acuity of 20/40 to 20/400 reexamined 6 days after initiation of treatment. INTERVENTION: Corneal scraping and cultures were obtained from study participants at day 6 after enrollment. MAIN OUTCOME MEASURES: We assessed 3-month best spectacle-corrected visual acuity (BSCVA), 3-month infiltrate/scar size, corneal perforation, and re-epithelialization rates stratified by culture positivity at day 6. Results Of the 323 patients with smear-positive ulcers enrolled in MUTT-I, 299 (92.6%) were scraped and cultured 6 days after enrollment. Repeat culture positivity was 31% (92/299). Among patients who tested positive at enrollment, those with positive 6-day cultures had significantly worse 3-month BSCVA (0.39 logMAR; 95% confidence interval [CI]: 0.24–0.44; P < .001), had larger 3-month scar size (0.39 mm; 95% CI: 0.06–0.73; P = .02), were more likely to perforate or require therapeutic penetrating keratoplasty (odds ratio: 6.27; 95% CI: 2.73–14.40; P < .001), and were slower to re-epithelialize (hazard ratio: 0.33; 95% CI: 0.21–0.50; P < .001) than those with a negative 6-day culture result. Conclusions Early microbiological cure on culture is a predictor of clinical response to treatment.