A thread inserted into a tampon or towel can detect Candida albicans overgrowth – also known as a yeast infection – within 10 minutes, scientists in ACS Omega in May. If the product is shown to work at home, the authors say, it could enable women around the world to diagnose yeast infections themselves quickly and inexpensively, thereby improving care, especially in high-risk settings. limited resources.

Currently, to confirm a diagnosis of yeast infection, a woman must see her doctor, have her vagina swabbed, and then wait 24 to 72 hours for the results of a PCR test. This is inconvenient for most women and extremely difficult for those with limited access to health care.

A diagnosis is not necessary for women to purchase over-the-counter antifungal treatments, so if they experience itching or other symptoms, they can assume they have a yeast infection and use treatment without being diagnosed. But the symptoms of a yeast infection – itching, burning, and changes in discharge – can be caused by a range of issues, from bacterial infections to allergies.

“Many women with these symptoms do not have yeast infections and use over-the-counter yeast infection medications unnecessarily. This diagnosis could potentially reduce the unnecessary use of yeast medications in the absence of yeast infections, ”explains Christine Metz, who studies molecular medicine at the Feinstein Institutes for Medical Research in New York City and was not involved in the study. Inappropriate use of these antifungals can delay appropriate care, waste time and money, and contribute to antifungal resistance.

The idea of ​​the diagnostic tampon started a few years ago, says Naresh Kumar Mani, a biotechnologist at the Manipal Institute of Technology in India and lead author of the study. “I was talking to my colleague – she is an obstetrician – and also with another colleague, a medical mycologist. We don’t give much importance to Candida albicans, although it is a disaster for the immunocompromised [people], newborns and women. While the common symptoms aren’t life threatening, Mani says, the fungus can wreak havoc if it manages to spread throughout the body. “Among intensive care patients, Candidiasis is the main fungal pathogen causing severe sepsis or septic shock. . . . It is therefore crucial to detect it at an early stage. Researchers set out to create a quick and inexpensive test to self-diagnose the infection.

First, they looked for a test that could detect an overgrowth of C. albicans in vaginal discharge. They landed on L-proline β-naphthylamide (PRO), a substrate that reacts to L-proline aminopeptidase, an enzyme produced by C. albicans and other organizations. PRO is used in lab tests and, according to Mani, has been around for 30 years, but has rarely been used clinically. It is a known carcinogen.

“These substrates, when they come into contact with the enzyme, undergo hydrolysis and cause a simple color change,” Mani explains.

Next, the researchers needed a way to make a matrix from yarn that could be incorporated into a tampon or towel and transport the substrate. The researchers chose tampons and pads because they wanted to incorporate their threads into products already on the market that can absorb enough L-proline aminopeptidase for it to be detected. Like most yarns, the ones the team bought from a local craft store had been treated with wax and hydrophobic binders that prevent them from absorbing liquids. So they washed the strings three times in a heptane solution to remove their coverings, treated them with the substrate, and threaded them into tampons and towels.

Because C. albicans Usually lives in the vaginal microbiome in small amounts, says Mani, the team identified the threshold at which infection occurs and designed the test to change color only when a sufficiently high concentration of the enzyme is present. They exposed the treated products to mock vaginal discharge enriched with C. albicans. When enough fungus was present to indicate a yeast infection, the threads turned pink. The more mushrooms, the darker the shade of pink.

The approach must be updated before it can be used. On the one hand, the fact that the threads turn dark pink can be a hindrance if women are to diagnose an infection during their period, as the color of the indicator could be obscured by blood. In addition, Metz points out that other pathogens, such as bacteria Clostridium difficile, can produce the enzyme L-proline aminopeptidase.

Mani says the team is also looking for analogs to the current substrate because PRO is a known carcinogen. Another limitation is that so far the product has only been tested with simulated samples, not on actual vaginal discharge or in a real environment.

Despite these limitations, Metz says “the inexpensive, simple and quick home method of detecting vaginal yeast infections is a breakthrough in improving women’s health.” Mani is currently working with collaborators in the US and UK to find PRO analogues and secure funding to bring the product to market.

“Self-diagnostic tools are important to increase access [to healthcare]”says Erica Cahill, a gynecologist at Stanford University, in an email to The scientist. “The most critical question is what will people do with tools like this? Will they be less likely to use drugs when they are negative (or will they still use them based on their symptoms)? Will they be more likely to seek treatment with a positive test?


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