An analysis of the bacteria and fungi in the mouths of HIV patients offers insight into the cause of painful thrush.

Scientists have discovered something new about candidiasis, also known as thrush, a common and uncomfortable mouth infection that can persist in people with HIV.

Thrush has long been a dreaded symptom of HIV/AIDS. In the early days of HIV, it emerged as an indicator that the disease had progressed to AIDS. Many also saw it as the first symptom of a previously unknown HIV infection.

Much like our guts, our mouths contain thousands of tiny microorganisms. In findings published today in PLOS Pathogens, researchers at Case Western Reserve University in Cleveland, Ohio, took an inventory of these bacteria and fungi from the mouths of 24 people. They compared what they found in the mouths of 12 healthy adults and 12 people with immune systems compromised by HIV.

With the exception of one woman in each group, all the participants were men. All were about 39 years old. Of the 12 HIV-positive subjects, eight had begun lifesaving antiretroviral therapy (ART), available to most people in the U.S.

Thrush is a hardy infection that persists even in an era of ART. In poorer countries where people do not have adequate access to ART, the problem is more widespread.

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Mahmoud Ghannoum, lead author of the new study, told Healthline that the bacteria found in the mouths of both the HIV-positive and healthy controls were similar. But fungi levels were different.

In both groups, the fungus Candida albicans was predominant. But in people with HIV, levels of candida were even higher.

In the healthy control group, high levels of the fungus pichia were found alongside candida. But in the HIV group, pichia levels were low. Mahmoud said this suggested an antagonism between the two microorganisms.

HIV-positive people are prone to fungal infections because of their compromised immune systems. Ghannoum and his colleagues hypothesized that a concentrated dose of pichia might control the run-away growth of candida in these patients.

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In a second experiment, the concentrated pichia “juice,” as Ghannoum calls it, significantly reduced candidiasis in mice infected with HIV and thrush.

Dr. John Perfect, chief of the Division of Infectious Diseases at Duke University, told Healthline that Ghannoum’s research offers “nice progress as a paradigm paper” in attempting to better understand thrush. He said laboratory advances are helping scientists learn more about the microbial communities living in our bodies.

Only five percent of the body’s cells are human, Perfect explained. The rest are comprised of bacteria, fungi, and viruses. “We’re the Starship Enterprise for a community of organisms that we carry around,” he said.

A better understanding of how these microorganisms work together may reveal clues about a host of health conditions, including obesity, Perfect said. “It’s very exciting, and just the beginning,” he added.

Ghannoum said further research is needed to answer some pressing questions. “Is it possible to use pichia as a probiotic?” he asked. “What is the component in the soup we got from the pichia that is inhibiting growth (of candida)?”

Ghannoum said he is currently working on a paper examining other oral complications experienced by people with HIV.

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Dr. Judith Aberg, another noted thrush researcher, told Healthline that the illness can be deadly. She said that recent surveys conducted by the Oral HIV/AIDS Research Alliance (OHARA) show that thrush remains a significant problem. More than 50 percent of those surveyed reported infections resistant to fluconazole, currently the most commonly prescribed medication for thrush.

Uncontrolled, thrush can spread to the esophagus and make if difficult to swallow. People may starve to death, Aberg said. Aberg is a board member of the HIV Medicine Association, a practicing HIV physician in New York City, and chief of the Division of Infectious Diseases at Icahn School of Medicine at Mount Sinai Hospital.

She pointed out that none of the HIV-positive participants in the study actually presented thrush symptoms, despite having fungal microbiomes different from those of the control group. “There will need to be subsequent studies confirming this and demonstrating that this is attributing to disease,” she said. “Whether a derivative of pichia as an antifungal or the use of the fungus as a probiotic is far too premature.”

But she said new treatments are much needed. While most of her patients have access to quality care and medication, in part because of a commitment by city and state agencies in New York, that is not the case everywhere.

Aberg said that thrush persists where quality HIV care is not available. “Remember that in resource-poor countries, they may have very good first-line therapies but few options for those who fail to suppress their HIV or have acquired resistant virus,” she said. “In these settings, the rates of oral candidiasis are no different than first reported in the [HIV/AIDS] epidemic.”

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