COVID-19 conditions in Brazil have opened the door for the emergence and spread of a relatively new fungus that is quickly showing signs of becoming a drug-resistant “superfungus,” according to a new report published in the Journal of Fungi.
Since December 2020, researchers have detected Candida auris in nine patients at a hospital in Salvador in Northeast Brazil.
Typically, fungi of the genus Candida are relatively harmless, most often causing treatable vaginal yeast infections and oral thrush. However, with a mortality rate of nearly 60%, C. auris presents differently—and patients with SARS-CoV-2 are ideal targets.
C. auris can enter the bloodstream, causing a systemic infection known as candidemia, which is similar to bacterial sepsis. Invasion of the bloodstream and the immune system's exacerbated response to the pathogen can then cause damage to several organs, ultimately leading to death.
“The species isn't very sensitive to the disinfectants used by hospitals and clinics," explained Arnaldo Colombo, lead author of the new study and head of the Special Mycology Laboratory at the Federal University of São Paulo (UNIFESP). "As a result, it's able to persist in hospitals, where it colonizes health workers and ends up infecting patients with severe COVID-19 and other long-stay critical patients.”
Of the nine patients at the hospital, Colombo said some presented with the fungus colonized, while others were infected and symptomatic.
“We're monitoring the evolutionary characteristics of C. auris isolates from patients at the hospital in Salvador, and we've already found samples with reduced sensitivity to fluconazole and echinocandins. The latter belong to the main class of drugs used to treat invasive candidiasis," said Colombo.
In fact, Colombo and his team have tested hospital samples for sensitivity to antifungal drugs every month since December 2020. In recent samples, the researchers have had to dose the culture with 4 to 5 times the amount of drugs to inactivate it compared with samples from last year and even the beginning of this year.
“The mechanism that enables the species to develop drug resistance isn't enzymatic degradation, as in so many bacteria that are resistant to antibiotics," Colombo said. "The fungus develops structural modifications in the proteins to which the drug binds to inhibit cell wall synthesis, which is key to its survival.”
Colombo’s group at UNIFESP is currently working with Dutch colleagues to genetically sequence the fungi to see if the gene that confers drug resistance on C. auris has mutated from December 2020 to now.
C. auris was first isolated in Japan in 2009, Asia and Europe in 2011, the Americas, Colombia, Panama and Chile in 2016, and finally Brazil in 2020. Thus far, 5 clades, or lineages, of the fungus have been described.
According to Colombo, the clade isolated in Salvador resembles the original Asian one more closely than the variant detected in Venezuela and other South American countries, suggesting a second independent arrival of the superfungus on the continent.
"Alternatively, there may be a local environmental source, since none of the Brazilian patients infected by the fungus traveled abroad or had infected relatives," Colombo said.
Regardless of origin, the research team is especially concerned about the superfungus as Brazil experiences a second wave of COVID-19 infections.
“In a near future, over-occupancy and limited resources for infection control practices, such as prolonged usage of personnel protective equipment due to shortages, will be a fertile ground for C. auris to spread, colonize invasive devices and deflagrate healthcare-associated infections,” the team concludes.
Photo: Fluorescence microscopy image illustrating morphology of C. auris. Credit: João Nóbrega Almeida Júnior/UNIFESP
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