Utility of MGG and Papanicolaou stained smears in the detection of Mucormycosis in nasal swab/scraping/biopsy samples of COVID 19 patients

Diagn Cytopathol. 2021 Dec 29. doi: 10.1002/dc.24924. Online ahead of print.


BACKGROUND: COVID 19 has been rapidly spreading across the globe. As a result of alteration of the immune milieu by COVID 19 and its treatment, there has been a rise in opportunistic fungal infections particularly Mucormycosis in these patients. Delay in diagnosis of these fungal infections can be fatal. The usual diagnostic modalities used to detect Mucor include potassium hydroxide (KOH) mount, fungal culture, and histopathology. Since histopathology and fungal culture have a long turnaround time we are dependent on KOH mount for rapid results. Here we investigate the role of stained cytology smears in the rapid diagnosis of Mucormycosis.

METHODS: A prospective observational study was conducted in a tertiary health care hospital on samples of patients clinically suspected to have Mucormycosis. We performed May Grunwald Giemsa (MGG) and Papanicolaou (PAP) stains on the remnant samples of nasal swabs/scrapings/biopsies after KOH test and fungal culture. We took 16 KOH positive and 16 KOH negative samples. We also examined 16 fresh samples from patients whose earlier samples were reported to be negative on KOH test.

RESULTS: The 6/16 KOH positive samples were found to be positive on stained cytology smears and 2 were mixed infections wherein both Mucor and Aspergillus were seen. The 4/16 KOH negative samples were positive for Mucor with one sample having both Mucor and Aspergillus. The 3/16 repeat samples which were earlier negative on KOH test were positive for Mucor.

CONCLUSION: Stained cytology smears if used in conjunction with KOH test can increase the overall sensitivity of detection of Mucormycosis and mixed infections.

PMID:34967146 | DOI:10.1002/dc.24924

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