Clinical perspectives and outcomes of Culture-Negative Microbial keratitis: A Retrospective study

Abstract

Abstract Objectives: To study the risk factors, clinical features, and treatment outcomes of patients with culture-negative keratitis (CNK). Methods: A total of 2347 patients of microbial keratitis, excluding clinically viral keratitis, were registered during the study period from January 2018 to December 2020. Out of this, a retrospective review of 933 patients' data with culture-negative keratitis was performed. The variables such as the history of injury, visual acuity, slit-lamp findings with measurements of size and depth of ulcer, microbiological evaluation, duct patency, blood glucose levels, and treatment were considered, and clinical outcome was analyzed. Results: Of the 933 patients with CNK, 763 (81.8%) were medically managed, with a mean treatment duration of 2.08 ± 1.7 weeks. Among them, 622 (66.7%) were both smear and culture negative, and 311 (33.3%) showed only smear positivity. Smear was positive for fungus in 23.8% of the patients with a history of trauma (P < 0.001) compared to those without trauma (8.3%). Also, higher incidence of fungal growth on repeat culture was noted. In 22.9% of the patients with a history of trauma, the infiltrate size was > 5mm compared to those without trauma (13.3%). Conclusion: The risk factors identified were trauma and the use of previous ocular medications. The culture-negative keratitis can be successfully managed with medications alone if repeat cultures are performed appropriately, empirical therapy includes broad-spectrum antibiotics and antifungals, and knowledge on clinical differentiation of infective keratitis.