Conventional and rapid diagnosis of fungal infections including mucormycosis linked to COVID-19

Abstract: Introduction: COVID-19 is a primary respiratory viral illness caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). It has been a challenge to diagnose COVID-19-associated mucormycosis as the clinical and radiological findings are nonspecific and could overlap. This study was done to estimate the incidence of various fungal infections during the COVID 19 pandemic and to evaluate the merits of conventional microbiological diagnostic approach. Method: All the nasal swabs and endoscopic biopsy samples received for fungal diagnosis from suspected mucormycosis COVID positive or COVID suspected patients were included in the study and were processed as per conventional microbiological techniques including direct KOH mount and culture growth on LPCB. Results: A total of 434 samples from suspected mucormycosis patients were received during the study period including 214 nasal swabs and nasal biopsies each, 1 sample each of nasal fluid, BAL and pus along with 3 sputum samples. The positivity rate in direct microscopy of swabs was 38.3%, and for tissue samples was 72.4%. Culture positivity rate was 47.6% amongst swabs with 19 Mucorales, 41 Aspergillus spp., 22 dematiaceious and 20 Candida spp. Culture positivity rate amongst biopsy samples was 40.6% with 35 for Mucorales, 36 for Aspergillus spp., 8 for dematiaceious and 8 for Candida spp. Conclusion: In our study, tissue samples had a greater culture positivity rate as compared to the nasal swabs, so they should be the preferred samples to be sent to the laboratory. However, nasal swabs performed better in culture growth, so their value need not be underestimated. In countries like India where RT-PCR not available in all clinical setups conventional techniques such as KOH wet mounts from samples and culture findings hold a promising outcome to start the antifungal therapy.