A study on the utility of KOH mount and HPR in the diagnosis of post COVID mucormycosis

Background: Mucormycosis is a deadly disease that mostly affects the immunocompromised. Steroid therapy following COVID-19 infection has led to an alarming rise in the rates of this rare infection. Key to management of this disease is early diagnosis. The most common modalities used for diagnosis are KOH mount and histopathological examination. In our study we compare the efficacy of these two diagnostic modalities. Methods: Nasal endoscopy was done in all suspected cases of the disease. Nasal discharge, crusts were collected in a sterile manner and sent for KOH mount examination. Specimens collected following surgical debridement was sent for HPR examination. The results of both are compared. Results: In our study, HPR was positive in 82.2% cases while KOH mount showed positive results in 43.5% cases only. Conclusions: Histopathology helps in confirming the diagnosis of mucormycosis. It also helps to demonstrate tissue invasion and identification of species of fungus. But it is time consuming. KOH mount examination is rapid and inexpensive but the test shows high false negative values. Thus, KOH mount examination can be used as a screening tool while histopathological examination can be used as a confirmation test for post covid mucormycosis.