https://doi.org/10.4081/mm.2025.13896
Mixed fungal co-infections in post-COVID patients - role of basic microbiology techniques for wider diagnosis
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Published: 2 March 2026
Background: the aim of the present study was to look for the type of fungi causing paranasal sinus/pulmonary infections in post-COVID patients, to study correlation between fungal KOH examination and fungal culture and to look for the type of fungal co-infections in these patients.
Material and Methods: this retrospective study was done on patients with post-COVID fungal infections between May 2021 to September 2021. The clinic-radiological diagnosis of fungal infection in these patients was confirmed by fungal smear KOH examination and/or fungal culture of pertinent samples. The demographic and clinical details of these patients were collected from hospital medical records.
Results: a total of 46 patients of post-COVID fungal infections were reported during study period. These were the cases of rhinosinusitis, rhino-sino-orbital and rhino-cerebral fungal infections and fungal pneumonia. Out of 46 samples 28 were suggestive of Zygomycetes infection and 18 were suggestive of mixed fungal infection on direct microscopic examination. On fungal culture, recovery of fungi could be done in 40 cases. The number of fungi isolated from 40 samples were 50. Different species of Rhizopus, Aspergillus and Fusarium were isolated.
Conclusions: our study depicts the occurrence of mixed fungal infections in post-COVID patients in India. These infections were caused by combination of both Rhizopus and Aspergillus as well as mixture of two different types of Aspergillus species. Our study underscores the meticulous utilization of basic microbiological techniques i.e., fungal KOH mount and fungal culture for the optimal isolation and identification of mixed fungal infections.
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