Spectrum of Microbial Keratitis in the Mid-Western Region of Nepal

Abstract

Introduction: Microbial keratitis is sight threatening infective keratitis caused by non-viral pathogens like bacteria, fungus or protozoa which may lead to blindness when neglected. It is the most common cause of unilateral corneal blindness which is a major public health concern for developing countries. Incidence of microbial keratitis in Nepal is higher (799/100000 per year) compared to developed countries like United States (11/100000 per year) due to varying epidemiological factors. Early clinical diagnosis, initiation of proper antibiotic therapy, identification of causative microorganism and management of predisposing factors together are necessary for rapid recovery and prevention of severe visual loss. 

Methods: This was a retrospective study of all consecutive patients diagnosed with suspected microbial keratitis and subjected to corneal scrapping in Cornea Department of Rapti Eye Hospital who attended during November 2021 to October 2022. The major outcome measures studied were predisposing factors, microbial spectrum, antibiotic sensitivity, treatment outcomes and surgical interventions required.

Results: A total of 68 eyes of 68 cases diagnosed with microbial keratitis and subjected to corneal scrapping were enrolled in the study. Mean age of the study participants was 49.6 ± 19.6 years and male to female ratio was 1.96:1. Ocular trauma was the most common predisposing factor (48.5% of cases) followed by use of steroid. Culture was positive in 36.8% of cases of which bacterial isolates were more common than fungal isolates. Streptococcus pneumoniae (37%) and Fusarium species (44.44%) were most common organisms among the bacterial and fungal isolates respectively. 

Conclusions: Streptococcus pneumoniae and Fusarium species are the most common bacterial and fungal species causing microbial keratitis in the mid-western region of Nepal with ocular trauma being the commonest predisposing factor. Cefazolin and fluoroquinolones are most effective antibiotics for Gram positive and Gram negative organisms.