Mucormycosis refers to severe infectious diseases that are caused by filamentous fungi of the Mucorales order that primarily affect immunocompromised patients and patients with diabetes mellitus. Recently, an increasing incidence has been reported among COVID-19 patients in India. The most common genera in invasive mucormycosis are Rhizopus, Rhizomucor, Lichtheimia and Mucor, accounting for 90% of all cases.
Clinically and radiographically, mucormycosis is often indistinguishable from other invasive fungal infections such as aspergillosis and remains difficult to diagnose. A definitive diagnosis of mucormycosis typically requires histopathological evidence or positive fungal culture from a specimen from the site of infection, which may be difficult to obtain in some patients.
A molecular diagnostic approach, detecting circulating DNA of Mucorales (by PCR) in serum of patients, may help to diagnose invasive mucormycosis more quickly and to introduce directed therapy earlier and eventually monitor treatment. Bronchoalveolar lavage (BAL), tracheal aspiration, sputum, pleural fluid, biopsy samples can also be used for the detection of Mucorales DNA. The sensitivity of Mucorales PCR from blood is inferior when compared to a Mucorales PCR performed on tissue samples (because the sampling is close to the site of fungal growth), but it is still largely acceptable. Mucorales PCR performed on blood present the advantage of being totally non-invasive. Mucorales spp detection depends on the collection of high-quality specimens, their rapid transport to the laboratory, and appropriate storage before laboratory testing.
Negative results do not necessarily indicate absence of mucorales infection. Positive results do not exclude co-infection with other pathogens. Other laboratory testing and assessment of clinical presentation must be included in the final diagnosis.
Early specific diagnosis and prompt therapeutic intervention with active antifungal treatment such as Amphotericin B are essential for improving the outcome of mucormycosis.
- Dr Prashant Goyal