A new blood test seems to perform as well as, if not better than, traditional blood cultures at detecting a type of fungal yeast infection that commonly strikes hospital patients, according to an analysis led by University of Pittsburgh Medical Center.
The T2Candida Panel is the first diagnostic test for candidemia that has been cleared by the U.S. Food and Drug Administration and doesn't require culturing a blood sample from the patient to see what grows. The results of the trial, named DIRECT2, are reported today in the journal Clinical Infectious Diseases. The trial was funded by T2 Biosystems, the company that makes the panel, which is used by UPMC.
"There are many advantages to quickly diagnosing the specific type of infection a patient has," said lead author Cornelius J. Clancy, M.D., associate professor of medicine in the University of Pittsburgh's Division of Infectious Diseases, and director of the mycology program. "With an accurate diagnosis, we can start the patient on the correct medication for the type of infection he or she has, which will hopefully allow us to stop the infection before it spreads, but also keep us from giving the patient a drug that won't work and potentially contributing to drug resistance. For candidemia, we know that the shorter the time to administering an active antifungal medication to a patient, the higher the survival rate. "
The T2Candida Panel involves putting a small vial of blood from the patient into a desktop machine that uses magnetic resonance to scan the blood for the five most common Candida species. Positive or negative results are available within five hours.
In the trial, the T2Candida test was positive in 89 percent of patients at the time of a positive blood culture for Candida. The T2Candida Panel was significantly more likely to be positive than blood cultures in patients with recent candidemia, in particular those patients who were being treated with antifungal drugs.
The assignment from Nichole Ward’s microbiology professor was simple: Choose a location, open a petri dish for three minutes and observe what grew over the next two days.
No one’s sample came back clean — a foregone conclusion given that a petri dish opened in any nonsterile room will collect microbes from the air. But when Ward returned to class with a dish that she had put in an enclosed Dyson hand dryer in a women’s restroom, the colonies of fungi and bacteria that had grown in it outstripped anything her classmates had found in their chosen locations.
"Mine just had so much more mass in the fungal growth," she said in a phone interview Thursday. "Their little colonies were just a speck here and a speck there. It just stood out by far."
Without further testing, which the class did not do, it is impossible to say whether the organisms in Ward’s petri dish were harmful to humans. But when she posted a photo on Facebook at the urging of her classmates, more than 500,000 people shared it in a matter of days.
Many horrified commenters vowed never to use a hand dryer again. Others ridiculed what they called unscientific fearmongering. Ward, who is taking the microbiology class as a prerequisite for a nursing program, said she had even received death threats.
Dyson, the manufacturer of the hand dryer she used, said in a statement to ABC that it was "very surprised to see these results, and unclear on the methodology employed." "All Dyson Airblade hand dryers have HEPA filters that capture particles as small as bacteria from the washroom air before it leaves the machine," the company said. "Dyson Airblade hand dryers are proven hygienic by university research and are trusted by hospitals, food manufacturers and businesses worldwide."
Whether hand dryers do, in fact, spread pathogens is a matter of dispute among scientists.
"The hot air will kill the bacteria on the hands, but some studies have found they will also deposit bacteria in the restroom on your hands — i.e., from the air," said Charles P. Gerba, a microbiologist at the University of Arizona.
A study published in 2016 in The Journal of Applied Microbiology found that jet air dryers — high-powered machines like the one Ward used — contaminated the surrounding area with 1,300 times as many viral particles as a paper towel would. Standard hand dryers — those that simply blow warm air — spread far fewer particles, but still 60 times as many as a paper towel. (Dyson said when that study was released that it had been conducted under unrealistic conditions: Participants’ hands were thoroughly coated with a virus, which would not be the case for a typical pair of just-washed hands.)
A similar study in 2014, using a bacterium instead of a virus, found that jet air dryers spread 4.5 times as much bacteria as warm air dryers, and 27 times as much as paper towels — but the study was funded by a trade association for paper manufacturers. Another study published in 2010 found that jet air dryers resulted in fewer bacteria on the hands than warm air dryers — but it was funded by Dyson.
One of the few independently funded studies on the subject, published by the Mayo Clinic in 2000, found no statistically significant hygienic difference between dryers and paper towels.
Related: California woman's viral Facebook post sparks fear of bathroom hand dryers