Bacteria in the mouth: What bacteria do we have in our mouths?

Bacteria in the mouth: What bacteria do we have in our mouths?

May 26, 2018 Off By Angel Hunt

Since we are born, bacteria in mouth begin to colonize our oral cavity. It is important to have good dental hygiene to keep pathogenic microorganisms at bay. The relationship between people and bacteria is something particular. Although some of these microorganisms attack us and are harmful to our health, many bacterial species live in harmony with us.

The mouth is a good example of bacteria storage since it has more than 600 species. Despite their small size, bacteria are of great importance to our oral cavity, since it depends on them that we have a healthy mouth or that we suffer from various conditions. Let’s see what bacterial microorganisms are lodged in our oral cavity and how they affect us.

Types of bacteria in the mouth

bacteria in the mouth

The oral bacterial flora is formed over the years. When we are in the uterus of our mother, the mouth is sterile. It lacks pathogens and, as soon as we are born. The oral microbiota begins to form, with the first colonization by bacteria of the maternal urogenital apparatus and of others present in the environment.

Initially, it is a microbial community with an aerobic majority -which lives in the presence of oxygen. With the emergence of anaerobic bacteria. Those that only live and proliferate in the absence of oxygen. Especially when the first teeth begin to sprout.

The humid and warm environment -about 35ºC- of our mouth, with different surfaces and nooks and crannies in which to roam freely. It is the ideal home for bacteria, so it is not surprising that it can house up to 100 million bacteria. According to researchers from around the world. In addition, the frequent presence of carbohydrates and sweets means that in addition to the home, oral bacteria also have food.

However, many of the bacteria that enter our mouth do not have such a happy ending: some die directly in the mouth, disintegrated by salivary enzymes. Others pass into the stomach when we swallow water, dying by the action of stomach enzymes. The problem arises when those who manage to survive act causing damage to our mouths.

The bacterial population that we have in the mouth is not fixed since our daily activity modifies that biodiversity. Eating, yawning, biting your nails or even kissing can change the oral bacterial flora, tilting the scales to one side or the other. A study by the Organization of Applied Scientific Research of the USA revealed that when two people kiss passionately they transfer to each other some 80 million bacteria. It leads couples to have a similar oral flora.

Changes in oral flora

But, in principle, the oral bacterial community is individual to each person, with the genetics and the environment that surrounds us as the main agents that shape the flora of the oral cavity. In fact, an investigation of the Ohio State University, in the United States, found that the bacteria in the mouth of human beings. Mainly those that accumulate under the gums. They are like a fingerprint that allows, for example, to identify the ethnic origin of the person.

Broadly speaking, there may be aerobic and anaerobic bacteria in the mouth, both gram-positive and gram-negative. Among anaerobic bacteria can sound already some names as lactobacillus or actinobacillus. In the case of aerobic bacteria, the type of genus they belong. Such as staphylococcus or streptococcus, can also become increasingly familiar.

Oral problems caused by bacteria

Oral problems

As we have said, many bacteria inhabit us performing positive functions for our body. However, there are others that cause damage. In the case of the mouth, bacterial pathogens cause.


This inflammation of the gums with loss of bone around the teeth is produced by the effect of bacterial plaque, which is nothing more than a bacterial biofilm that forms on the hard surface of the tooth and the gum that supports it. The roughness and depths of the dental enamel help the bacteria to adhere to the bottom of the grooves. Resisting the action of the water. Anaerobic bacteria are in the deep part of the bacterial plaque and aerobic bacteria in the upper part.


Bacteria transform sugars and starches into acids, which dissolve the enamel of the teeth – demineralization – and create holes that can reach the dental pulp.

Bad breath

There are different bacteria that contribute to halitosis or bad breath. For example, Gram-negative break down protein or fatty foods, in addition to blood and cells. It generates sulfur compounds responsible for bad mouth odor.

Mouth pain

In addition, bacteria in the mouth can extend their invasive action beyond the oral cavity and generate other types of conditions. For example, one of the bacteria present in bacterial plaque can enter the bloodstream and trigger infectious endocarditis. It is a disorder that causes inflammation of the heart valves with a risk of blockage of blood to the heart and brain. It is a frequent pathology in those people operated on with heart or prosthetic heart valves.

Another example of pathologies associated with oral bacteria is cancer. A study by the University of New York, in the United States, concluded that the presence of certain bacteria in the mouth may reveal an increased risk of pancreatic cancer. Another work by US scientists, this time from Case Western Reserve University, revealed that a common oral bacterium can contribute to colorectal cancer.

For all this, it is clear how important it is to have a proper oral hygiene to keep under control the effects of pathogenic bacteria in the mouth and avoid oral disorders as well as other infections. Do not forget to brush your teeth daily and use dental floss to clean where the toothbrush does not reach.

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