Evaluation of Sensitivity and Specificity of Direct Microscopical Examination of Suspected Mucor Mycosis Samples by Potassium Hydroxide (KOH) during Covid-19 Pandemic Era

Abstract

Introduction: Mucormycosis is a common fungal infection in India even before the COVID-19 pandemic. The incidence of Mucor mycosis has entered public consciousness in response to an outbreak of cases in India during COVID-19 pandemic. Mortality is unacceptably high, reaching 80% in some case series. Prompt diagnosis is crucial because treatment initiation is time-critical due to the rapid progression of the infection. Direct KOH mount is a simple, rapid, inexpensive point-of-care test, which requires minimum technical aids. Interpretation of KOH smears requires some amount of experience. The present study was to evaluate the sensitivity and specificity of Direct Microscopical examination by KOH preparation of suspected Mucor mycosis samples taking the fungal culture as gold standard. Material and Methods: 230 samples were received in Microbiology Department from May 2021 to August 2021 from the patients suspected of Mucor mycosis. Samples were processed for KOH preparation using different concentrations of KOH like 20% and 40% till all tissues get digested. Samples were cultured also in Sabourauds dextrose agar (SDA) medium. Results of microscopy and culture were statistically analyzed using SPSS software version 23. Result: Sensitivity of KOH preparation was 67%, specificity was 87%. Positive predictive value was 76% and negative predictive value was 81% and accuracy was 80% when compared with the fungal culture. Discussion: Direct microscopic examinations using KOH preparation are the simplest, cheapest method used for the diagnosis of mycotic infections. This study is valuable in establishing a reliable method for early information on diagnosis of Mucor mycosis that may be crucial for determining appropriate therapy for the successful treatment of Mucor mycosis patients. Conclusion: KOH examination plays an important role in the diagnosis of Mucor mycosis suspected patients during COVID-19 pandemic era when compared with fungal culture which is a gold standard test in diagnosis of Fungal infection. It is the simplest and cheapest method that can be developed easily with minimal infrastructure or human resources in resource-limited countries during the COVID-19 era.