2023-05-27 12:50:27
Identified only in 2009, the pathogen can be fatal for immunologically deficient people. Non-specific symptoms and drug resistance increase the risk of C. auris. Lack of serious research on fungi is also aggravating.
In the United States, infections with the fungus Candida auris are exploding: in 2022 there were 5,754 cases, against 1,310 two years earlier. Although it seems small compared to a population of 332 million, doctors are alarmed.
In October 2022, the World Health Organization (WHO) ranked this type of mycosis among the 19 most dangerous on its list of priority fungal pathogens (WHO FPPL).
The superfungus is also a concern in Brazil: since Tuesday (23/05), a hospital in Pernambuco has been in total isolation, due to the registration of at least three infections. The first case in the country was identified in December 2020, in Bahia.
The danger of infection is especially high for those who have a weakened immune system as a result of an operation, chemotherapy or otherwise. This is why the fungus spreads mainly in healthcare facilities and hospitals.
Oliver Cornely, from the Center for the Study of Infectious Diseases at the University of Cologne Clinic, explains that “the weakening or collapse of the immune system frees the way for the fungus to affect different regions of the body”.
Among them, especially the circulatory system, the digestive tract and certain tissues. “If the fungus contaminates the bloodstream, it can result in sepsis. After penetrating the tissues, at some point it will reach a blood vessel, it is transported by the blood and thus reaches all the organs.”
Invasive mycoses such as that triggered by Candida auris are among the most frequent and fatal infectious diseases: of the more than 1 billion humans who contract them each year, about 1.5 million die.
Resistance to antimycotics and survival on surfaces
Scientists estimate that there are about 3 million fungal species, of which 300,000 have already been identified. Only between 150 and 300 are described as human pathogens, accounting for 90% of deaths from mycoses.
Candida auris is the most recent among the identified yeast fungi capable of establishing itself in humans. It was first described in 2009, having erupted at the same time in different parts of the world, for unknown reasons. However, only in recent years has it manifested itself more frequently.
“We all carry different fungi in the body. As a rule, the defense system keeps them in balance, so that those who are healthy do not have any problems”, explains Cornely.
One of the factors that makes Candida auris very dangerous is its resistance to drugs: “Resistance is not only formed during therapy, with the adaptation of the pathogen to antimycotics: this fungus is practically born resistant. It makes him harder to fight.”
The species produces the biofilm, a protective layer that makes it resistant to fluconazole, amphotericin B and echinocandin, three of the main antifungal compounds
Another characteristic of C. auris is that it survives outside the body: it can settle on the skin of anyone who touches a contaminated surface and, “by holding hands with an immunologically debilitated patient, one could be immediately transmitting the fungus”.
This exceptionally high survival capacity also explains the current explosion of infections: it is not a case of panic, but mycoses must be taken seriously, and there is a need for better methods of diagnosis, warns the scientist.
Non-specific symptoms, drugs are lacking
Making the diagnosis of Candida auris difficult, the symptoms of an infection are non-specific, starting with fever and chills. In addition, it can settle in different parts of the body, including inside the tissues, where it is not visible.
When there is suspicion of an infection, a smear is performed, which is seeded in fungal culture for molecular-biological and morphological identification. However, this process can take days, in which the superfungus continues to reproduce and the patient’s chances of survival are reduced.
“If for 24 hours a patient receives the wrong treatment or none at all, because it is not clear what pathogen it is, it may be that their organs have already suffered irreparable damage”, explains Cornely.
When a diagnosis is presented, antimycotics are given. However, in the case of Candida auris there are not many options, and the effectiveness varies from case to case. There is a lack of new drugs, and scientists complain that research on mycoses is extremely neglected, despite the high risk potential.
Three other dangerous fungi
After animals, fungi make up the second largest organic kingdom. In humans, they preferentially settle in the mucous membranes of the mouth and sexual organs, as well as in the lungs and intestines – but not all of them are pathogenic.
In the WHO FPPL list, “critical priority” fungi are those that primarily affect humans and can cause serious illness. In addition to Candida auris, three others make up the category: identified longer, diagnosis is easier.
Candida albicans is another yeast fungus found frequently in the human body, living mainly in the skin, mouth and intestine. As long as it is in balance with other microorganisms, it does not usually cause problems. But in individuals exposed to high doses of antibiotics or with poor hygiene, it can cause candidiasis. Its most frequent symptoms are itching and redness of the skin, but it can also affect vital organs.
Equally frequent is the mold fungus Aspergillus fumigatus, usually contracted through the respiratory tract. Found in large quantities in the soil and in decaying matter, in the most serious cases it can cause lung infections such as invasive aspergillosis.
Cryptococcus neoformans also enters the body by aspiration. From the lung, it can spread to the brain, causing severe headaches or neurological disorders, including cryptococcal meningitis, which causes fever, convulsions and even paralysis.
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