OkayToKiss test targets bacterial source of bad breath

Jun 29, 2009

Tel Aviv University (TAU) researchers have developed a pocket-sized breath test they say can detect malodorous bacteria in the mouth and alert people that they could have bad breath.

The patent-pending OkayToKiss test is the result of ongoing research on the bacteria that cause bad breath.

Until now, scientists believed that only one population of bacteria -- the Gram-negative ones -- break down the proteins in the mouth and produce foul odor. But TAU researchers have discovered that another population of bacteria -- the Gram-positive ones -- are bad breath's bacterial partner.

These bacteria appear to help the Gram-negative ones by producing enzymes that chop sugary bits off the proteins and make them more easily degraded.

Mel Rosenberg, Ph.D., a professor in TAU's Sackler Faculty of Medicine, co-developed the kit with Dr. Nir Sterer of the same school. They published their research findings earlier this year in the Journal of Breath Research (March 2009, Vol. 3:1).

"For about seven years now we've suspected that there's another kind of bacteria at work in the mouth which causes bad breath," Rosenberg said. "Now we are able to grow these bacteria from saliva in an artificial biofilm, showing that there are two distinct populations at work."

Research findings

This is the first time that Gram-positive bacteria have been associated with bad breath, Rosenberg said. The Journal of Breath Research paper is the third in a series of work led by Dr. Sterer, he added.

"We recently suggested that oral malodor production involves two steps: deglycosylation of glycoproteins, and proteolysis and amino acid utilization of the protein core to yield volatiles such as volatile sulfide compounds (VSCs)," the authors wrote in the March study. "Our aim was to test the hypothesis that β-galactosidase activity and VSC production occur in distinct areas of the biofilm by two different bacterial populations."

The researchers grew biofilms anaerobically for seven days and stained them for β-galactosidase activity and VSC production, then studied them using confocal laser scanning microscopy. Results showed that β-galactosidase activity occurs in the outer layers, whereas VSC production occurs deeper within the biofilm.

A blue stain indicated β-galactosidase activity within the biofilm, while a red stain indicated VSC production.

The blue staining was highly concentrated in the outer layers of the biofilm, the researchers found. In contrast, the VSC production indicated by red staining was situated deeper within the biofilm.

"These findings suggest that β-galactosidase activity is produced mainly by Gram-positive oral bacteria at the outer portion of the biofilm, and VSC production occurs in the deeper layers by Gram-negative oral," the authors concluded.

How it works

The enzymatic assay for the level of β-galactosidase became the basis for the the OkayToKiss test, Rosenberg noted.

The OkayToKiss device comprises a color indicator and saliva collector. Users can dab a little bit of saliva onto a small window of the OkayToKiss test. The saliva is then put in contact with a chromogenic substrate for the β-galactosidase, Rosenberg explained. If the enzyme produced by Gram-positive bacteria is present, the substrate will turn blue.

He hopes to have the test ready for commercial distribution within a year to 18 months, once a manufacturer and distributor are found. It is disposable and could be distributed alongside breath-controlling products, he noted.

The test could also be used as an indicator of a person's oral hygiene, encouraging better health habits, such as flossing, brushing the teeth, or scheduling that long-delayed visit to the dentist, Rosenberg added.

"This test will enable people to determine privately whether they have a risk for levels of this enzyme, which we have shown to be correlated with bad breath," he said.