Candida auris

Candida auris is so tenacious, in part, because it is impervious to major antifungal medications, making it a new example of one of the world's most intractable health threats: the rise of drug-resistant infections.(stock image for illustration purposes)
In May, an elderly man was admitted to the Brooklyn, New York City branch of Mount Sinai Hospital for abdominal surgery. A blood test revealed that he was infected with a newly discovered germ as deadly as it was mysterious. Doctors swiftly isolated him in the intensive care unit.

The germ, a fungus called Candida auris, preys on people with weakened immune systems, and it is quietly spreading across the globe. Over the past five years, it has hit a neonatal unit in Venezuela, swept through a hospital in Spain, forced a prestigious British medical centre to shut down its intensive care unit, and taken root in India, Pakistan and South Africa.

Recently, C. auris reached New York, New Jersey and Illinois in the United States, leading the federal Centers for Disease Control and Prevention to add it to a list of germs deemed "urgent threats."

The man at Mount Sinai died after 90 days in the hospital, but C. auris did not. Tests showed it was everywhere in his room, so invasive that the hospital needed special cleaning equipment and had to rip out some of the ceiling and floor tiles to eradicate it.

"Everything was positive - the walls, the bed, the doors, the curtains, the phones, the sink, the whiteboard, the poles, the pump," said Dr. Scott Lorin, the hospital's president. "The mattress, the bed rails, the canister holes, the window shades, the ceiling, everything in the room was positive."

C. auris is so tenacious, in part, because it is impervious to major antifungal medications, making it a new example of one of the world's most intractable health threats: the rise of drug-resistant infections.

For decades, public health experts have warned that the overuse of antibiotics was reducing the effectiveness of drugs that have lengthened life spans by curing bacterial infections once commonly fatal. But lately, there has been an explosion of resistant fungi as well, adding a new and frightening dimension to a phenomenon that is undermining a pillar of modern medicine.

"It's an enormous problem," said Matthew Fisher, a professor of fungal epidemiology at Imperial College London, who was a co-author of a recent scientific review on the rise of resistant fungi. "We depend on being able to treat those patients with antifungals."

Simply put, fungi, just like bacteria, are evolving defences to survive modern medicines.

Antibiotics and antifungals are both essential to combat infections in people, but antibiotics are also used widely to prevent disease in farm animals, and antifungals are also applied to prevent agricultural plants from rotting. Some scientists cite evidence that rampant use of fungicides on crops is contributing to the surge in drug-resistant fungi infecting humans.

Yet as the problem grows, it is little understood by the public - in part because the very existence of resistant infections is often cloaked in secrecy.

With bacteria and fungi alike, hospitals and local governments are reluctant to disclose outbreaks for fear of being seen as infection hubs. Even the CDC, under its agreement with states, is not allowed to make public the location or name of hospitals involved in outbreaks. State governments have in many cases declined to publicly share information beyond acknowledging that they have had cases.

All the while, the germs are easily spread - carried on hands and equipment inside hospitals; ferried on meat and manure-fertilised vegetables from farms; transported across borders by travellers and on exports and imports; and transferred by patients from nursing home to hospital and back.

C. auris, which infected the man at Mount Sinai, is one of dozens of dangerous bacteria and fungi that have developed resistance. Yet, like most of them, it is a threat that is virtually unknown to the public.

Other prominent strains of the fungus Candida - one of the most common causes of bloodstream infections in hospitals - have not developed significant resistance to drugs, but more than 90 per cent of C. auris infections are resistant to at least one drug, and 30 per cent are resistant to two or more drugs, the CDC said.

Dr. Lynn Sosa, Connecticut's deputy state epidemiologist, said she now saw C. auris as "the top" threat among resistant infections. "It's pretty much unbeatable and difficult to identity," she said.

Nearly half of patients who contract C. auris die within 90 days, according to the CDC. Yet the world's experts have not nailed down where it came from in the first place.

"It is a creature from the black lagoon," said Dr. Tom Chiller, who heads the fungal branch at the CDC, which is spearheading a global detective effort to find treatments and stop the spread. "It bubbled up and now it is everywhere."

As the CDC works to limit the spread of drug-resistant C. auris, its investigators have been trying to answer the vexing question: Where in the world did it come from?

The first time doctors encountered C. auris was in the ear of a woman in Japan in 2009 (auris is Latin for ear). It seemed innocuous at the time, a cousin of common, easily treated fungal infections.

Three years later, it appeared in an unusual test result in the lab of Dr. Jacques Meis, a microbiologist in Nijmegen, Netherlands, who was analysing a bloodstream infection in 18 patients from four hospitals in India. Soon, new clusters of C. auris seemed to emerge with each passing month in different parts of the world.

The CDC investigators theorised that C. auris started in Asia and spread across the globe. But when the agency compared the entire genome of auris samples from India and Pakistan, Venezuela, South Africa and Japan, it found that its origin was not a single place, and there was not a single auris strain.

The genome sequencing showed that there were four distinctive versions of the fungus, with differences so profound that they suggested that these strains had diverged thousands of years ago and emerged as resistant pathogens from harmless environmental strains in four different places at the same time.

"Somehow, it made a jump almost seemingly simultaneously, and seemed to spread and it is drug-resistant, which is really mind-boggling," Vallabhaneni said.-New york times