Pathogenetic factors fanning the flames of COVID-19 to cause rhino-orbito-cerebral mucormycosis: An observational study

Background and aims: Published studies on coronavirus disease 19 (COVID-19) associated rhino-orbito-cerebral mucormycosis (CAROCM) were primarily descriptive. Therefore, we aimed to identify features of COVID-19 that could predispose to CAROCM and explore the pathogenic pathways.

Patients and methods: This retrospective hospital-based study was done during the first (March 2020 - January 2021) and the second (February 2021 - June 2021) waves of the COVID-19 pandemic. Subjects were grouped into four categories: first-wave CAROCM (n-4); second-wave CAROCM (n-27); first-wave non-mucor COVID (n-75), and second-wave non-mucor COVID (n-50). Data elements included age, gender, comorbidities, COVID-19 severity, steroid therapy, peak values of interleukin-6 (IL-6), serum ferritin and D-dimer, nadir values of absolute lymphocyte count (ALC), absolute neutrophil count (ANC) and platelet count (Pl. C).

Results: Thirty-one patients of CAROCM were included. The mean (SD) age was 51.26 (11.48) years. 27 (87.1%) were aged ≥ 40 years and males. Severe COVID-19 was seen more often in the second wave than the first wave (P-0.001). CAROCM group was significantly younger (P-0.008) and showed a higher incidence of uncontrolled diabetes (P-0.001) and renal dysfunction (P-0.004) than non-mucor COVID. While IL-6, ferritin and D-dimer were significantly elevated in CAROCM than non-mucor COVID, clinical severity, ANC, ALC and Pl. C showed no significant difference.

Conclusion: CAROCM is seen often in middle-aged diabetic males with uncontrolled hyperglycaemia, diabetic ketoacidosis, renal dysfunction and those infected by more transmissible delta variants and treated with steroids. IL-6, D-dimer, serum ferritin are more often elevated in CAROCM and might play a pathogenic role.