Image of Candida auris fungus.
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A few months ago, researchers from the National Institutes of Health made an unexpected discovery. They were in the Microbiology Laboratory to process water samples collected in various studies. Among them was a mixture of fresh water flowing from land and salty seawater that was collected more than 400 kilometers from Bogotá, in northwestern Colombia. After several tests, the scientists found that a pathogen called Candida auris lived there. (Read Are taxes on sugary drinks losing steam in the tax?)
C. auris is not an unknown organism. “It is part of a large group of fungi (genus Candida) with the ability to cause disease in the host, whether human or animal. What’s happening with this pathogen in particular is that we don’t know a lot of things for sure, including its origin and its habitat in the environment. What we found, consistent with international studies, suggests that the natural environment of C. auris may be bodies of water,” said Patricia Escandon Hernandez, coordinator of the INS Microbiology Group at the Public Health Research Directorate and author of the study , which reviews the finding, published in the international academic journal Journal of Fungi. (Read some details about a death that occurred at a university in Bogotá=
This is not the first isolation of C. auris in the country, many have already been done in hospitals and in infected patients, but it is the only one so far that gives clues as to where it lives. The reservoir in which it is located is located in an area with little human activity around it and with the presence of diverse fauna and flora. Finding it in a natural environment may be essential to understanding the significance of C. auris.
a true mystery
The first time doctors found it in a patient was in Japan in 2009, in the ear of a 70-year-old woman admitted to Tokyo Metropolitan Geriatric Hospital (auris actually means ear in Latin). It seemed like a sporadic case of yet another microorganism, one of thousands that are present not only in the environment but even on people’s skin. Dr. Escandon says, for example, that if a sample of her skin were taken now, it would reveal the presence of fungus, bacteria and parasites. But few of them have the real capacity to cause damage, and that’s thanks to the protection we humans have: our temperature.
The body temperature, the one announced by the thermometer, if you measure it on a normal day, can vary between 36 ºC and 37.5 ºC, depending even on the time of day you measure it. This figure remains constant because humans are homeothermic creatures, that is, we regulate and maintain our temperature even if it is cold outside. This is an evolutionary advantage: body heat prevents infection from viruses, bacteria and fungi that survive only to certain degrees. The case of the woman in Japan was therefore unusual: until then, C. auris had never been reported to have the ability to overcome this natural barrier. Soon the situation took on a different tone. (Read Columbia Hospital Among World’s Best in 2022)
In 2016, six years after the Japanese case, hospitals around the world, but especially in South Korea, South Africa, Kuwait, and India, began to report the identification of C. auris infection in dozens of patients hospitalized in hospitals. . Little by little, it became clear that it was a pathogen that experts call “opportunistic”: it tends to take advantage of the weak immune systems of already sick and critical people to attack. Therefore, it is common and poses a risk mainly to hospitalized patients. Someone healthy is not at risk for this infection.
According to the US Centers for Disease Control and Prevention, C. auris infection is invasive and can affect the blood, heart, brain, eyes, bones and other parts of the body. More than one in three patients die in the U.S. in the month they’re diagnosed, although, Escandon says, it’s hard to tell if that’s the main cause of death because these are patients who already have clinically serious status .
While the World Health Organization sounded the alarm in 2016 by creating worldwide warnings about this fungus, many questions remained in the air. And the main one was and still is why this happened. What caused C. auris to be able to break body temperature?
“Some authors suggest that this is due to climate change. Living in a natural environment, which can be water, it adapts to an increase in temperature. One hypothesis is that it was this warming that led to the evolution of the fungus: by surviving at higher temperatures, it was able to overcome our protective barriers,” explains Escandon. “That’s why it’s key to be sure what the natural habitat of the pathogen is in the environment.” When C. auris evolved, birds are thought to be the animals that made it possible for it to spread around the world. Cases have multiplied in Europe, where the pathogen has led to the complete closure of hospital wards.
In late June 2016, for example, an article published in the British specialist journal BMC reported an “ongoing outbreak of 50 cases of C. auris” at the Royal Brompton, a major heart and lung medical center in the United Kingdom. The hospital closed its intensive care unit for a week, but did not say why. During the first months of the outbreaks, this silence was also constant. Matt Richtel, a renowned Pulitzer Prize-winning reporter for the New York Times, wrote in 2019 regarding this difficulty that he had never faced “such a difficult and unexpected journalistic challenge”: “A doctor in Spain wrote to me that I didn’t want the hospital to be bad in the press, that it looks like an outbreak of fungus”, he gave as an example.
The characteristics of “C. auris
Between 2012 and 2013, long before the outbreak caught the world’s attention, an intensive care unit at a tertiary care hospital in Maracaibo, Venezuela, reported 18 patients affected by what they believed to be another fungus, Candida.haemulonii. Later, in 2016, the Pan American Health Organization recognized this outbreak in Venezuela as the first of C. auris in the Americas. That same year, Columbia Hospital on the North Shore reported five cases of C. auris infection, although it initially misidentified them.
“One of the specific problems with this fungus is that it is not easily identified by the conventional methods that a hospital might have. This led to misidentifications,” explains Dr. Escandon. Since 2016, and in line with the rest of the world, the INS has issued a national alert for the emergence of C. auris, leading to the implementation of national notifiable surveillance. In the first months, three departments made the notification; today 80% of the country does. Since then, Colombia can have 1,720 positive cases in patients located in 62% of the national territory.
For this identification, it is not sufficient to report a probable case of infection. The subject must isolate it and send the sample to INS, where it is confirmed or discarded in more sophisticated laboratories. Fortunately, says Escandón, the majority of Colombian cases respond to antibiotic treatment, an advantage they do not have in Europe or even the United States, where, since it became clear that C. auris is an opportunistic pathogen that is difficult to diagnose , doctors noticed that he was not responding to treatment. Medications commonly used to treat other Candida infections often have no effect on C. auris.
There are three main classes of drugs to treat these infections: the so-called azoles, polyenes, and echinocandins. According to the CDC, approximately 85% of C. auris isolates in the US are resistant to the former and 33% to the latter. Only 1% can resist third parties, which is why these types of drugs have become essential for the treatment of the disease.
However, in the early months of 2021, the United States Network of Antibiotic Resistance Laboratories found independent clusters of C. auris cases resistant to the three drugs, particularly in Texas and the District of Columbia. None of the patient groups had been previously exposed to these drugs, a fact that suggests to the CDC that the transmission of multidrug-resistant strains of C. auris is occurring in the United States for the first time.
Because of all these features, Escandón concludes, it is key to continue looking for answers to the open questions that this fungus still leaves behind. After the unexpected find recently published in Colombia, the INS is preparing to make collections in different water bodies in different areas of the country. While scientists from all over the world are trying to clarify doubts, health institutions are still required to report any appearance of fungi in hospitals and clinics in Colombia.
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