Repeat cultures may guide treatment of severe fungal keratitis

This secondary analysis of the Mycotic Ulcer Treatment Trial II (MUTT II) found that patients with a positive 6-day fungal culture carry a high risk of corneal perforation.

Study design

Investigators analyzed 208 smear-positive filamentous corneal fungal ulcers. All patients had vision of 20/400 or worse, were on topical antifungals, and were randomized to receive oral voriconazole or a placebo. All corneas underwent corneal scraping and culture at presentation and at 6 days.

Outcomes

The authors found that eyes with persistent positive corneal cultures at 6 days had nearly twice the risk of corneal perforation or therapeutic keratoplasty compared with those who tested negative. At 3 months, vision in the 6-day culture-positive group was 0.26 logMAR worse than other patients, even after controlling for baseline characteristics such as infiltrate size and depth. Neither the time to re-epithelialization nor the 3-month infiltrate size differed significantly.

Limitations

This is study is regionally limited, in that all patients were recruited in South Asia. As such, the representative organisms, which excluded common pathogens such as Candida, may not represent the global spectrum. Likely due to the given social conditions, the recruitment rate was also very low. This could confound the results.

Clinical significance

This study presents compelling evidence to consider a second culture at 6 days in the setting of fungal keratitis to help guide further therapy. Continued culture positivity, per these results, may place eyes at elevated risk for perforation and indicate a need for early intervention.