Microorganism shows promise in inhibiting thrush

March 13, 2014
Treatment of mice with Pichia spent medium reduces the extent of tissue invasion by Candida (see arrows) in the tongue. This image shows (A) untreated and (B) Pichia spent medium treated mice tissue. Credit: Mahmoud Ghannoum

Scientists at Case Western Reserve School of Medicine and University Hospitals (UH) Case Medical Center have discovered how the beneficial fungal yeast, Pichia, holds at bay a harmful fungal yeast, Candida. The hope for this finding is that components in Pichia could one day become therapeutic agents to stave off not only thrush, but also other life-threatening systemic fungal infections. Research findings about the effect of oral Pichia on Candida appear in the March 13 edition of PLOS Pathogens.

"Our aim was to try to understand what microorganisms live in our mouths. A disturbed equilibrium of these microorganisms can lead to disease," said the study's senior author Mahmoud A. Ghannoum, PhD, EMBA, professor of dermatology and pathology at the School of Medicine and director of the Center for Medical Mycology at UH Case Medical Center.

The study involved testing the mouths of 24 from UH Case Medical Center—12 HIV infected and 12 not infected with HIV. HIV-infected patients were selected for comparison in the study because thrush is a common occurrence for them. The oral cavity was tested for fungi and bacteria using pyrosequencing, a method that uses DNA analysis, which is more powerful with greater specificity than conventional, culture-based approaches.

"When we looked at the data, we found to our surprise that bacteria did not change much between HIV-infected patients and those who were not," Ghannoum said. "However, what changed significantly between the two groups was the composition of the fungal community. We found that when Candida is present, Pichia is not, and when Pichia is present, Candida is not—indicating Pichia plays an important role in treating thrush."

From these observations, investigators conducted in vitro (test tube) experiments on Candida and Pichia. When they grew Candida in the test tube in the presence of Pichia, there was a striking reduction in Candida growth. They also discovered that Pichia secretes material, or a protein, that controls Candida. This Pichia-secreted material, referred to as supernatant, inhibits biofilm formation, germination and adherence in Candida, factors that mark a microbe's level of harmfulness.

Investigators then took their findings to the next level with experiments on three groups of Candida-infected mice. One group of mice was treated with Pichia supernatant. The next group was treated with nystatin, a topical treatment for thrush. Still another group received no treatment. The outcome? In the mouths of the Pichia-treated mice, the level of Candida was nearly eradicated, though traces remained. Even the nystatin-treated mice had far more Candida present than the Pichia-treated mice. Additionally, the physical symptoms, such as tongue appearance, improved in the Pichia-treated group.

"One day, not only could this lead to topical treatment for thrush, but it could also lead to a formulation of therapeutics for systemic fungal infections in all immunocompromised patients," he said. "In addition to patients with HIV, this would also include very young patients and patients with cancer or diabetes."

As a next step this year, investigators will study Pichia supernatant to identify its components that inhibit Candida and other fungi.

Explore further: Research uncovers potential preventive for central line infection

More information: Mukherjee PK, Chandra J, Retuerto M, Sikaroodi M, Brown RE, et al. (2014) Oral Mycobiome Analysis of HIV-Infected Patients: Identification of Pichia as an Antagonist of Opportunistic Fungi. PLoS Pathog 10(3): e1003996. doi:10.1371/journal.ppat.1003996

Related Stories

Probiotic treatment for vaginal thrush on the way

February 18, 2014

Scientists are testing vaginal pessaries containing 'good' probiotic bacteria for the treatment of vaginal thrush. Research published today in the Society for Applied Microbiology's Journal of Applied Microbiology shows that ...

Recommended for you

Monkeys in Asia harbor virus from humans, other species

November 19, 2015

When it comes to spreading viruses, bats are thought to be among the worst. Now a new study of nearly 900 nonhuman primates in Bangladesh and Cambodia shows that macaques harbor more diverse astroviruses, which can cause ...

One-step test for hepatitis C virus infection developed

November 14, 2015

UC Irvine Health researchers have developed a cost-effective one-step test that screens, detects and confirms hepatitis C virus (HCV) infections. Dr. Ke-Qin Hu, director of hepatology services, will present findings at the ...

Computer model reveals deadly route of Ebola outbreak

November 10, 2015

Using a novel statistical model, a research team led by Columbia University's Mailman School of Public Health mapped the spread of the 2014-2015 Ebola outbreak in Sierra Leone, providing the most detailed picture to date ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.