Microbes in the mouth and respiratory diseases: prevention is better than cure.

In the first part of the article, we saw how the oral microbiota, that is, the set of all microorganisms living in our mouths, can play a crucial role in keeping not only the mouth itself, but also our entire body, healthy.

Indeed, there is a correlation between alterations in the oral microecosystem and certain diseases affecting the airways, such as COPD, pneumonia, and lung cancer.

The previous article closed by reminding that observing a correlation does not necessarily imply a causal relationship. It could be, in fact, that the altered balance among microorganisms in the mouth causes, or at least promotes, the onset of lung-related diseases; but the opposite could also be true, i.e., that it is the airway diseases, which are already present, that reflexively affect the oral microflora as well, causing an imbalance; just as it is equally possible that there is no cause-and-effect relationship between the two conditions, which simply occur in the same patients at the same time.

Come si difende dalle infezioni il nostro organismo?

To protect ourselves from infection, our bodies deploy a number of very effective defenses. These include the use of very aggressive compounds, such as nitrogen oxides or reactive oxygen species, which are produced by our immune system and used as chemical weapons against invaders. We also have the complement system that patrols the body and attacks any outsider. We can also make use of the help of antibiotic substances or disinfectants. The same bacteria that live as hosts on our mucous membranes produce toxic substances for pathogens, such as hydrogen peroxide or nitrites. They also compete for the same nutrients, so they prevent the late entrants from finding the resources they need to grow.

Come fanno, quindi, i microrganismi patogeni a sfuggire a tutte queste barriere difensive del nostro corpo?

Pathogens try to evade our defensive strategies using a wide variety of stratagems, which fortunately for us very rarely work. To counteract oxidizing species, they produce hydrogen. To defend themselves against nitrites, some produce an enzyme that detoxifies them. To get rid of antibiotic substances, they produce proteins that actively pump them out of the cell. To stick more to surfaces and hide from the immune system, they produce adhesive substances. Finally, genetic mutations contribute to much variability, which could give rise to increasingly resistant strains. Really fierce, these little guys!

This is why disrupting the oral microecosystem can promote the colonization of the respiratory tract by pathogens. For example, saliva and lactic acid produced by endogenous microbes inhibit the growth of undesirable bacteria such as the Pseudomonas . Le dysbiosis (alterations in microbial flora), the periodontitis and the stomatitis (inflammation of the gums and mouth), the use of dentures, smoking, some chemotherapies and radiotherapies, immunodepression, and other diseases can go on to alter the composition and amount of saliva produced, leading to poor oral hygiene and a shift from a normal microflora to a more pathogenic one. Decreasing the number and variety of oral commensal bacteria also leads to lower defenses against pathogens because their growth is less inhibited by “good bacteria.”

Come tenere sotto controllo le malattie respiratorie partendo dalla salute della bocca?

Taking care of our oral hygiene personally or by using dentists and dental hygienists is a first step. In fact, it has been noted that patients with respiratory diseases have a common tendency not to floss, not to attend dental offices regularly, and to brush their teeth inappropriately. The dissemination of knowledge and good practices related to oral health, therefore, can be helpful in the prevention and treatment of respiratory tract diseases, as has also been shown by some studies.

Elderly patients require special care and attention, and it has been observed that encouraging access to hygiene done by professionals reduces the risk of pneumonia and hospitalization for respiratory diseases. Even for coma patients, it has been noted that brushing teeth twice a day reduces infections by nearly 70%.

The use of oral antimicrobial substances, such as iodopovidone or chlorhexidine reduces the risk of developing infections, as does employing specific antibiotics that can keep at bay those bacteria that, of their own, are not pathogenic, but may promote colonization or virulence of pathogenic ones. This represents a bit of the future of therapies: thinking not about the individual microorganism as if it were isolated, but thinking about theentire network of interactions in the oral ecosystem.

The use of probiotics . It has been seen that oral lactobacilli and streptococci have the ability to limit the growth of pathogens; therefore, in some cases, the probiotics can be used to improve oral health and thus go so far as to prevent lung infections.

Thus, although there is still little etiological evidence correlating the oral microecosystem with respiratory diseases, there are already some indications that these two worlds are related to each other and may influence each other. The mechanisms by which this can occur remain to be studied in more detail, and then to understand how to better prevent or treat these diseases.

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