Volume 2 - Issue 3
Ragya Bharadwaj1,*, S. Thilagavathy2
1Infection Control Officer, Kauvery Hospital, Trichy, Tamilnadu, India
2Consultant Microbiologist and Head of Diagnostic Laboratory, Neuberg Ehrlich Laboratory & Kauvery Hospital, Trichy, Tamilnadu, India
It was way back in March 2020, when the World Health Organization made us aware of a pandemic named COVID-19. Emerging in a small city of Wuhan in Central China's Hubei province, it managed to inflict its wrath on even the remotest parts of the world. Scientists and researchers at large struggled to find an effective treatment strategy for the disease. We managed to roll out vaccines against the virus in later part of 2020 itself. An effective vaccination programme driven by countries, supported by international and national organizations should be able to control and curb this pandemic.
First wave was heavily felt in most parts of the western hemisphere. India managed to keep the situation under control with effective lockdown strategies and preventive measures. We noticed many secondary bacterial infections, in recovering and recovered patients. Few immunocompromised individuals showed isolation of fungal species like Mucor sp. and Aspergillus sp. There was a significant decrease in number of COVID-19 cases in India at the beginning of December 2020.
Then came the second wave which was more widespread and devastating than the first. In India, it brought along a drastic increase in secondary fungal infections. A particular fungus was more rampant than any others which caused a disease namely "Mucormycosis". Mistakenly labelled "Black Fungus", Mucor is an opportunistic fungus residing in the environment, especially on dead, decaying organic matter. Our government had even declared it as a notifiable disease due to sudden rise in number of cases especially during second time around. To dispel a myth, Mucor is not contagious.
Belonging to the phylum Mucormycota, order Mucorales, they typically grow as white to beige colored colonies on the environmental surface with height of several centimeters. Older colonies start turning grey to brown due to development of spores. Prakash et al., estimated the difference between Mucorales mean spore count between indoors (0.68-1.12 CFU/m3) and outdoors (0.73-8.60 CFU/m3) . Mode of infection is mainly via inhalation of spores in environment.
On light microscopy stained with KOH, they appear as broad, ribbon like, hyaline (transparent), aseptate or sparsely septate hyphae with right angle branching. In general, mucor are unable to infect humans and endothermic animals due to their inability to grow in warm climes. Most common species infecting susceptible humans are Rhizopus arrhizus.
In India, the predominant presentation of this disease was Rhino- orbital- cerebral mucormycosis. Other clinical presentations were pulmonary mucormycosis seen in carcinoma or transplant patients, gastrointestinal, in premature babies, cutaneous in trauma or burns patients- and Renal mucormycosis.
According to many distinguished mycologists, higher incidence of this disease was seen in India even before COVID-19 pandemic, most important etiological factor being uncontrolled diabetes (31% prevalence) in our country. During the second wave there was sudden abuse of systemic steroids as well as an increasing burden of this disease. Other factors contributing to increase in cases were high patient load with no effective control of their diabetes. Oxygen crisis was faced by many states with resulting overuse of high dose steroids to manage hypoxemia. Unproven facts about etiology which are under study are the virulence of both delta strain and Rhizopus sp. causing infection during recent times.
Many researchers have postulated pathogenesis of this fungal pathogen co-inhabiting patients with Covid-19. Steroid overuse and Diabetes are the forerunners. Steroids cause impairment of neutrophil migration thereby causing phagolysosomal fusion impairment and raises blood sugars. The virus itself causes stress and an hyperinflammatory state, releasing cortisol and adrenaline, indirectly resulting in increase of sugars. Other mechanisms namely cytokine storm, increase insulin resistance, damaged blood vessels supplying pancreas, alteration of iron metabolism all caused Mucor to infect even the patients who were not hospitalized.
Diagnosing this disease posed several challenges for microbiologists. A good tissue without disturbing the integrity of the cells including blood vessels is the preferred sample. The organism is a rapid grower, hence use of common available culture media suffice in its isolation. Radiographic tool of choice is magnetic resonance imaging preferably with contrast. Many treatment options are available for this organism, but timely aggressive intervention is required as Mucor being angioinvasive, spreads rapidly destroying anything in its path. Choice of antifungal is liposomal Amphotericin B.
We conclude by highlighting the preventive measures, which is the answer to any emerging pathogen. A good glycemic control is of utmost importance. Correct indication for use of systemic steroids in hypoxemic patients with dose and duration of therapy limited to Dexamethasone - 0.1 mg/kg/day for 5-10 days. Certain environmental measures like frequent disinfection of patient surroundings, repairing any water leakages in the wards, universal masking of patients during admission and post discharge are also important. Other measures like early identification of signs and symptoms should be explained to the patient as well.
We hope to combat this rare but complicated illness primarily through prevention, and secondarily, through effective and timely intervention to help our patients have optimal and safe outcomes.
Prakash H, Ghosh AK, Rudramurthy SM, Paul RA, Gupta S, Negi V, et al. The environmental source of emerging Apophysomyces variabilis infection in India. Med Mycol. 2016;54(6):567-75.
Dr. Ragya Bharadwaj