Sensitivity of KOH Mount in the Early Diagnosis of Fungal Infections of Nose and Paranasal Sinuses in COVID-19 Infected Patients Suspected with Mucormycosis

Abstract

Introduction: Mucormycosis represents a group of life threatening infections caused by fungi of the order Mucorales especially in Coronavirus Disease 2019 (COVID-19). It is a highly invasive and rapidly progressive disease resulting in high grades of morbidity and increased mortality. Aim: To study the sensitivity of potassium hydroxide (KOH) mount in the early diagnosis of mucormycosis in COVID-19 infected patients. Materials and Methods: A prospective, longitudinal (single group) study was done in McGANN Teaching District Hospital, Shimoga Institute of Medical Sciences, Shivamogga, Karnataka, India, among the patients with high index of clinical suspicion of mucormycosis from May 2021 to August 2021. Specimen from the nasal cavity or the suspected lesion on hard palate, gums, skin was sent for KOH mount and fungal culture and also biopsy of the nasal mucosa sent for histopathological examination. The sample was sent both preoperatively and intraoperatively. The positive KOH report and its role in early diagnosis and management of mucormycosis suspected cases were assessed. Results: Out of 26 patients, 6 (23.1%) were females and 20 (76.9%) were males. COVID-19 positive suspected mucormycosis were 5 (19.2%) and post COVID-19 suspected mucormycosis were 21 (80.8%). Species isolated after processing the sample were rhizopus in 10 (38.5%), candida in 1 (3.8%), aspergillus in 1 (3.8%); while in 14 (53.8%) no organisms were isolated. Out of 26 patients KOH positive sample on the day of admission confirming with positive intraoperative histopathological examination were 10 (41.7%). Admission day fungal culture positivity was seen in (n=12, 46.2% ) and negativity in 14 (53.8%) cases. Intraoperative fungal culture was positive in 24 (92.3%) cases. There was 100% specificity for both fungal culture and KOH mount and sensitivity for KOH was 41.7% and 50% for fungal culture. False negativity rate for KOH was 58.3% and for fungal culture was 50%. Conclusion: The results of KOH mount can be obtained within an hour of sending nasal scrapping samples. Hence, it helps in making the early diagnosis and early initiation of treatment for suspected cases. But in the current study, even in patients presenting with high clinical suspicion of mucormycosis, the sensitivity of KOH mount on the day of admission to the hospital was 41.7%.In view of severe morbidity and mortality of mucormycosis, this sensitivity though less is of paramount importance in these patients because treatment can be started early.

Keywords

• coronavirus disease 2019
• fungal culture
• potassium hydroxide
• microscopy
• sensitivity