Saliva keeps bad bacteria in check

May 29, 2018


Why does our body’s immune system allow bacteria to grow in our mouth? We know that the mouth contains over 700 types of bacteria.

They grow on the tongue, cheek, gums and teeth. Most of the bacteria are harmless when it comes to our health. The bacteria that cause us problems such as tooth decay and gum disease don’t just grow randomly and alone, but join together into complex microbial biofilms.

Our body has defenses against bacteria; otherwise bacteria would overgrow, and the inside of our mouths would look like that piece of moldy bread left out on the counter for days. Until now, we could not explain how our immune system controls the number of bacteria growing in our mouth.

New research from UCLA Dental School discovered that our saliva communicates with oral bacteria and regulates the growth of the bacteria responsible for diseases such as periodontitis and meningitis. If the research is correct, our saliva actually manages the amount of good and bad bacteria in our mouth. Most bacteria are divided into two types: gram negative or gram positive.

Most of the bacteria responsible for gum disease are gram negative. The gram-positive bacteria are very susceptible to our antibiotics, such as penicillin. The gram negative are not. The UCLA research found that our saliva, and other body fluids such as tears and blood, controls gram negative bacteria by sending out information that confuses their production.

If you remember from science class, DNA is genetic code of life. To grow and reproduce requires our DNA replicating by dividing in half and creating RNA. It appears that our saliva produces a type of RNA that confuses and regulates the reproduction of bacteria. Instead of killing bacteria, saliva produces a kind of birth control pill for gram negative bacteria.

The current approach to fighting an infection is by using antibiotics. The problem is that in addition to killing bad bacteria, antibiotics also kill harmless bacteria that are beneficial to health. It appears that our saliva has the ability to control the growth of bacteria. We just need to understand how exactly the system works. The UCLA researchers are optimistic that this finding will lead to a new approach at fighting gum disease and possibly other diseases caused by gram negative bacteria.

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