Hypoxia key factor in driving mucormycosis: Researchers

A rapid response to an article on black fungus (mucormycosis) in the British Medical Journal has said low oxygen saturation levels in patients is a key trigger for the fungal infection. A rapid response is an online comment by a third party.

The rapid response has been written by six doctors from Karnataka, three of whom are members of a sub-committee on mucormycosis set up by the state government. The doctors said oxygen was critical to several biochemical processes, making survival under hypoxic conditions a factor of increased virulence for some human pathogenic fungi. This could explain why some patients, despite not having high sugar levels or not having been exposed to a hospital setting, still developed the fungal infection.

The authors include Rajiv Gandhi University of Health Sciences' Vice Chancellor Dr S Sachchidanand (Chairman of the State Covid-19 Expert Committee), Dr Sampath Chandra Prasad and Dr Vishal Rao, who are both members of the state Covid task force.

Dr S Sachchidanand told DH, "Patients who are hypoxic offer a conducive environment for the fungus to grow. In fact, it is one of the leading causes of mucormycosis."

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Karnataka, as of June 25, has 3,146 cases and 257 deaths; Bengaluru accounts for 1,026 cases and 80 deaths.

Speaking to DH, Dr Vishal Rao, Dean, Centre for Academic Research, HCG (which has more than 60 patients) said, "The sub-committee on mucormycosis is trying to understand the cause behind jump in cases. The factors that were at play in the second wave that were absent in the first wave were the rise in Covid cases needing oxygen and the delta variant.

We looked at diabetes and steroid use as factors too. What we came to understand is hypoxia is one of the main factors driving the infection rather than oxygen being the culprit. Hypoxia is a key determinant that activates fungal elements."

In May, an expert panel had submitted a report to Health Minister K Sudhakar that use of industrial oxygen for medical purposes and sharing of oxygen cylinders by two patients for a few hours each were some of the causes driving the fungal infection in the State.

"At the peak of the second wave, when oxygen supplies were in short, oxygen was being rationed, hospitals were trying to maintain patients at low oxygen levels between 90 and 94. Low oxygen concentration becomes an ideal environment to nurture fungus growth. This is a hypothesis," added Rao.

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Dr Sampath Chandra Prasad Rao, a skull base surgeon at Manipal Hospital (which has 57 patients), and a co-author of the rapid response said, "This rapid response was from our collective experience of treating patients at various centres. It will be statistically validated soon.

We've proposed a scoring system (which includes history of hypoxia among 30 data points) now for Mucormycosis which the state government has accepted. Majority of those who were scored at Manipal, for example, had hypoxia.

Currently, unless we provide culture report or hispathology report, the patients are not allocated Liposomal Amphotericin B by the government. But Mucormycosis is notorious for throwing up a false negative report."

"So now, if the scoring is high, the patients will be categorised as probable or likely to have mucormycosis. Based on this the government will consider them eligible for Liposomal Amphotericin B. We have also developed a Mucor App where data can be collected from various centres based on the scoring system," he said.