Candida auris: what is the ‘superfungus’ that killed 2 people and has 3rd outbreak in Brazil

The National Health Surveillance Agency (Anvisa) issued a public health threat alert because of the third outbreak in Brazil of Candida auris, a drug-resistant fungus responsible for nosocomial infections that has become one of the most feared in the world.

According to the agency, in a document dated January 11, 2022, two cases of infection by the fungus were identified in the first month of this year involving a 67-year-old patient and another 70-year-old who were hospitalized in a public hospital in Recife. Updated information about their health status was not released.

Throughout the Covid-19 pandemic, Anvisa confirmed 18 cases of the infection in three different outbreaks. The first confirmed case was identified in a sample from the tip of a catheter from a patient hospitalized in an ICU in Salvador, site of the first two outbreaks: one in December 2020 (with 15 cases and two deaths in a private hospital) and another in December 2021 (with a case in a public hospital).

But can you call it an outbreak with this relatively small amount of cases? According to Anvisa, “it can be considered that there is an outbreak of Candida auris because the epidemiological definition of an outbreak encompasses not only a large number of cases of contagious or health-related diseases, but also the emergence of a new microorganism in the epidemiology of a country or even a health service — even if it is just one case” .

The infection by C. auris it is drug resistant and can be fatal. Worldwide, it is estimated that invasive fungal infections of C. auris have led to the death of between 30% and 60% of patients. But these numbers usually vary a lot depending on the variables involved, such as the severity of the disease that took the patient to the hospital (such as Covid-19) and the ability of the fungus to resist or not the drugs.

According to Anvisa, this species of fungus produces “antifungal-tolerant biofilms showing resistance to drugs commonly used to treat Candida infections” and up to 90% of Candida auris analyzed point to resistance to fluconazole, amphotericin B or echinocandins.

In its alert, Anvisa says that it has analyzed suspected cases of the fungus since 2017, but the first were only confirmed during the Covid-19 pandemic. And Brazil was not the only one to register infections of this type in this period linked to the new coronavirus.

In the United States, the Centers for Disease Control and Prevention (CDC) recorded 1,156 clinical cases of Candida auris between September 1, 2020 and August 31, 2021. There is no information on the death toll. As of 2016, the fungus has been detected in only four US states. The number would jump to 19 states by 2020.

In Mexico, an outbreak of Candida auris started with a patient who was not infected with coronavirus in May 2020, when the San José Tec-Salud hospital, in the north of the country, was transformed into an exclusive health unit for patients with Covid-19.

Three months later, the fungus Candida auris was detected in three ICUs and reached 12 patients and three hospital areas. Ten were men, nine were obese and all of them breathed with the aid of mechanical respirators, had urinary and venous catheters and were hospitalized there for 20 to 70 days. Of the 12 patients, eight died.

The researchers who analyzed the cases list several risk factors for the emergence of fungal infections. Among them, diabetes, use of multiple antibiotics, kidney failure, use of a central venous catheter and, in the specific case of Covid-19, excessive use of corticosteroids (which have an immunosuppressive effect on neutrophils and macrophages, cells of the body’s defense system). human).

In India, the candidemia outbreak hit 15 coronavirus patients in an ICU in New Delhi between April and July 2020. Of the total, ten were infected with Candida auris and six of them died.

In the case of Brazil, a group of ten Brazilian and Dutch researchers investigated the first outbreak in Salvador, in December 2020, and the relationship of cases with Covid-19. According to an article published in March 2021 in the Journal of Fungi, all the patients affected were from the state itself (Bahia), had no history of travel abroad and were hospitalized in the same ICU because of the coronavirus.

“Travel restrictions during the Covid-19 pandemic and the absence of travel history among patients colonized by fungi led to the hypothesis that the species was introduced months before the first case was identified and/or that it emerged locally in the region. Salvador region.”

Another hypothesis raised by the researchers points out that the patients were already infected with the Candida auris before becoming seriously ill with Covid-19. When admitted to the ICU, “they were intensely exposed to antibiotics and invasive medical procedures, and developed superinfections.”

The Covid-19 pandemic, therefore, “may be accelerating the introduction and/or spreading the Candida auris in hospital environments that were free of the fungus”.

And they conclude: “In the near future, overcrowding and scarcity of resources for infection control practices, such as the prolonged use of personal protective equipment due to lack of availability, will be fertile ground for C. auris spread, colonize invasive devices (such as a catheter) and trigger healthcare-associated infections”.

According to Anvisa, the Candida auris “it can remain viable for long periods in the environment (weeks or months) and is resistant to several disinfectants, including those based on quaternary ammonium”.

Difficult to control and prevent

In most cases, yeasts of the genus Candida they reside in our skin, mouth and genitals without causing problems, but they can cause infections when our immunity is low or when invasive infections, such as in the bloodstream or lungs, are provoked.

In case of C. auris, it often causes infections in the bloodstream, but it can also infect the respiratory system, central nervous system and internal organs, as well as the skin.

This fungus, which grows like yeast, was first identified in 2009 in the ear canal of a patient in Japan. Since then, there have been more than 5,000 cases identified in 47 countries, including India, South Africa, Venezuela, Colombia, the United States United States, Israel, Chile, Canada, Italy, Netherlands, Venezuela, Pakistan, Kenya, Kuwait, Mexico, United Kingdom, Brazil and Spain.

The average mortality rate is estimated at 39%, according to calculations in a study by seven Chinese researchers published in the scientific journal BMC Infectious Diseases in November 2020.

According to infectious disease specialist Arnaldo Lopes Colombo, a professor at Unifesp (Federal University of São Paulo) and a specialist in fungal contamination, it is possible to be temporarily colonized by the C. auris on the skin or mucosa without having problems. The fungus poses a real risk if it contaminates the bloodstream.

For a person to be infected, he explained to BBC News Brazil in 2019, they must have undergone invasive procedures (such as surgeries, use of a central venous catheter) or have a compromised immune system. Patients hospitalized in intensive care units for long periods and with previous use of antibiotics or antifungals are also considered a risk group for contamination.

In 2016, PAHO, the arm of the World Health Organization for Latin America and the Caribbean, published an alert recommending the adoption of prevention and control measures due to outbreaks related to the fungus in the region. The first outbreak in the region occurred in Venezuela, between 2012 and 2013, reaching 18 patients.

In addition, the C. auris it is often confused with other infections, leading to inappropriate treatments.

“THE C. auris survives in hospital environments and therefore cleanliness is critical to control. Discovery [do fungo] can be a serious issue for both patients and the hospital, as control can be difficult,” explained Dr Elaine Cloutman-Green, Infection Control Specialist and Professor at University College London (UCL).

Not all hospitals identify the C. auris Likewise. Sometimes the fungus is confused with other fungal infections, such as common thrush.

In 2017, a study published by Alessandro Pasqualotto, from Santa Casa de Misericórdia de Porto Alegre, analyzed 130 laboratories of reference medical centers in Latin America and found that only 10% of them have the capacity to detect invasive fungal diseases according to standards. Europeans.

According to Anvisa, the 2016 outbreak in Cartagena, Colombia, is an example of how difficult the microorganism is to identify. Five cases of infection were identified as three different fungi until a more modern method of analysis correctly diagnosed the pathogen as C. auris.

It is also not possible to eliminate it using the most common detergents and disinfectants. It is important, therefore, to use the proper cleaning chemicals from hospitals, especially if there is an outbreak.

In an alert issued in 2017, Anvisa explained that the most accurate mode of transmission of the fungus within a health unit is not known for sure. Studies indicate that this can occur through contact with contaminated surfaces or equipment and from person to person. The CDC also states that the fungus can stay on the skin of healthy patients without causing infection and spreading to other people, for example.

In an interview with BBC News Brasil in December 2020, Pasqualotto, also a professor at the Federal University of Health Sciences of Porto Alegre (UFCSPA), stated that cases of Candida auris they are like “an adverse event of the progress of humanity”.

“As we progress, we produce more antibiotics, as people are more invaded by medical procedures and survive longer, new pathogens that previously did not cause diseases begin to emerge. And, due to the pressure of medicines, they emerge resistant”, he said. he.

“So the Candida auris it’s just the ball at the time. As was the Staphylococcus aureus, who developed penicillin resistance after World War II; then the Enterococcus vancomycin resistant and so many others. We have fewer antibiotics to use and more and more resistant pathogens.”

Microbial resistance, which involves fungi and bacteria, is considered one of the greatest threats to global health by the World Health Organization (WHO). It happens because microorganisms have evolved and become stronger and more adept at evading drugs such as antibiotics and antifungals, causing many diseases to have few or no treatment options available.

drug resistance

Resistance to common antifungals such as fluconazole has been identified in most strains of C. auris found in patients.

This means that these drugs do not work to fight the C. auris. Because of this, less common fungicidal medications have been used to treat these infections, but the C. auris also developed resistance to them.

“Resistance to azoles, echinocandins and even polyenes, such as amphotericin B, has been reported. This means that the fungus may be resistant to the three main classes of drugs available to treat systemic fungal infections,” explained epidemiologist and microbiologist Alison Chaves on Twitter. , shortly after the discovery of the first outbreak in Salvador at the end of 2020.

It is estimated that more than 90% of infections caused by C. auris are resistant to at least one drug, while 30% are resistant to two or more drugs.

DNA analyzes also indicate that antifungal resistance genes present in the C. auris have passed on to other fungal species, such as Candida albicans (C. albicans), one of the main causes of candidiasis (a common disease that can affect the skin, nails and genitals, and is relatively easy to treat).

With additional information from Mariana Alvim and Letícia Mori, from BBC News Brasil in São Paulo.