New analysis reveals human mouth carries more germs than expected

BY KRISTIN WEIDENBACH © Stanford University. All Rights Reserved. Stanford, CA 94305. (650) 723-2300.

The human mouth is awash with bacteria. Mostly neighborly bugs, they live on our teeth and gums, helping to digest food and to ward off attack by less friendly, disease-causing bacteria that can steal their way in.

Stanford researchers have now shown that more of these oral inhabitants exist than previously thought. Using a combination of old and new scientific methods to study a scraping of plaque from a healthy human mouth, the researchers found evidence of 37 unique bacteria that microbiologists had never before recorded. Some were closely related to bacteria that scientists are familiar with, but others were very different.

Knowing more about the bacteria that reside in a normal, healthy mouth may help physicians understand changes in the bacterial population that can lead to gingivitis, periodontitis and tooth decay.

“Our data suggest that a significant proportion of the resident human bacterial flora remain poorly characterized, even within this well-studied and familiar microbial environment,” said David Relman, MD, assistant professor of medicine and of microbiology and immunology at Stanford, and lead author of the study published in the December 7 issue of the Proceedings of the National Academy of Sciences. Relman and colleagues conducted the research in his lab at the Veterans Affairs Palo Alto Health Care System.

According to Relman, the subgingival crevice — the deep gum pocket cradling each tooth — has been repeatedly scrutinized in the search for microbes. Even though almost 500 bacterial strains have been identified already, Relman believes this may be only a fraction of the bacteria living in this oral groove.

Oral bacteria have traditionally been studied by taking a scraping or sample from inside the mouth, growing the bugs in the laboratory and then identifying different species according to biochemical tests and the type of food source that each bacteria prefers. Using this method, the Relman team identified bacteria found in a sample of plaque taken from the subgingival crevice.

They also searched the same sample using molecular techniques. Instead of nurturing the bacteria in the lab, they prepared DNA directly from the plaque and studied each genetic sequence that had a bacterial signature. Comparing the results, they found that the molecular method yielded many new bacteria. Not only did the method reveal bugs that had never before been found in the mouth, many were bugs that had not yet been documented by microbiologists.

The team discovered 31 bacteria using the molecular method. In contrast, the traditional approach, which only identifies bacteria that can be cultivated in the lab, uncovered only six new bugs.

“Sequence-based environmental microbial surveys have taught us that cultivation methods woefully underrepresent the true extent of bacterial diversity,” said Relman.

Although the cultivation method traditionally used by clinical microbiology labs did not uncover the bacterial diversity revealed by the molecular technique, the researchers found that some bacteria were more readily recovered the old way, indicating that DNA analysis and cultivation both have a role in the comprehensive study of human microbial populations.

Characterization of previously undocumented oral bacteria is part of the Relman team’s larger effort to identify rare and unusual microbes that make their home in the human body — many cohabiting benignly but some causing mysterious human disease.

Ian Kroes, MD, lead author of the study, was a medical student in Relman’s lab at the time the research was conducted. Paul Lepp, PhD, a postdoctoral fellow in the lab and the third member of the research team, conducted much of the DNA analysis.

The research was funded by the Donald E. and Delia B. Baxter Foundation and the Lucille P. Markey Charitable Trust. SR

For the past 14 months, the world has struggled to find ways to slow the spread of the novel coronavirus but a new pandemic is hiding right in front of our faces! The use of masks, gloves, and other single-use plastics has increased dramatically and disrupted global efforts to reduce the use of plastics and decrease plastic pollution, an issue that has been documented by EP Online. As mask wearing and mask mandates were announced in an effort to reduce transmission, a new challenge began to emerge: What do we do with all these single-use masks? We’ve all seen them thrown on the ground in parking lots or

Buy Reusable Masks

Whether you are wearing masks by choice or by local or regional mandates, if you are still using disposable masks, it is time to consider switching to reusable, cloth masks. The efficacy of cloth masks has been documented by multiple organizations including Mayo Clinic, Centers for Disease Control and Prevention, MIT Medical and University of Maryland Medical System. All of these organizations and academic institutions have drawn the same conclusion: Cloth masks are an effective solution to reduce transmission of coronavirus and COVID-19 in most environments and in non-patient-care settings. Reduce your waste production by switching from disposable, single-use masks to reusable cloth masks.

Responsibly Dispose of Your Used Mask

Don’t throw your mask on the ground! If you have made the choice to stick with single-use masks, make sure they are disposed of properly. Disposable masks do not require special disposal like sharps or medical waste. In this case, responsible disposal simply means making sure masks are thrown away in the trash, not left in parking lots, abandoned in shopping carts, or casually dropped outside of a retail store, school or gym.

Single use masks are typically made with polypropylene, a type of plastic, and are not biodegradable. Polypropylene can take hundreds of years to break down. Leaving masks on the ground is littering and it’s bad for the environment. When you are finished using a disposable mask, make sure it ends up in a trash can where it belongs.

Provide Additional Disposal Stations

Whether you are a business that had chosen to require customers wear mask or located in an area that has a mask mandate in effect, make sure you are providing your customers and guests with plenty of convenient options for mask disposal. Adding a few extra trash collection bins outside your doors to make disposal easier can dramatically reduce the amount of masks that end up scattered across your parking lot and property.

Abandoned masks are unsightly and bad for the environment. Adding a few trash cans and additional signage is an easy, cost effective solution to prevent the problem before it starts.

Make Earth-Friendly Choices

Plastic is generally the most cost effective option for single use products, and single use items are soaring in popularity because of concerns around COVID transmission. While it may be harder than ever to reduce reliance on these single-use, plastic items, we encourage everyone to remember to do what they can to reduce waste, choose reusable products and materials, opt to buy items with recyclable packaging and always recycle when possible. https://www.therecycleguide.org/stop-the-mask-pandemic/