Our bodies are colonised by billions of all kinds of micro­organisms that differ in shape, size and function, depending on the area they live in. The community of microorganisms that live in or on our bodies is known as the human microbiome. A microbiome is also defined as the combined microbial genetic material in a particular area or environment.

Most of the microbes that we share our bodies with contribute to our wellbeing, so much so that we would not exist without them. Two of the most studied human microbiomes are the oral and gut micro­biome. In these areas health is achieved through a balance between the resident microorganisms and the human immune system.

In the gut, the useful bacteria can be lost after anti­biotic treatments, which can lead to symptoms such as diarrhoea. In our mouths, accumulation of food particles because of infrequent brushing ‒ plaque ‒ can lead to oral diseases such as gum disease due to a loss of balance between the useful and the disease-inducing microorganisms.

Traditionally, diseases caused by microorganisms have been solely treated by antibiotics. These medicines inhibit the growth of a group of microorganisms. Although antibiotics are sometimes necessary and lifesaving, their excessive use has led to antibiotic resistance. This occurs when the microorganism causing the disease adapts and starts to be unaffected by the treatment. This is where research on the role of probiotics to treat diseases is vital.

Probiotics are microorganisms, generally bacteria or yeasts, that are alive at the time of consumption and are intended to increase the useful bacteria in the system. This helps to reestablish a balance and therefore reduces the disease-inducing microbial population. Probiotics have gained popularity particu­larly as an aid for gut health, but increasing research is highlighting their potential benefits in oral health.

Despite recent advances in probiotic research, there is still a lot to learn on how we can use these microorganisms to our advantage. This is because there are many different types of probiotics to be studied, and also because recreating the oral or gut microbiome is extremely complex.

Our research at the Faculty of Health Sciences, funded by a Marie Skłodowska-Curie Individual Fellowship (MSCA-IF), aims to develop innovative probiotics, as well as testing techniques for use as an oral health aid. Lessons learnt from this research can be translated to other fields and lead to further research in the fascinating world of microbes.

Cher Farrugia is a dentist and a microbiology researcher.

Sound Bites

• Faecal bacteriotherapy

Also known as faecal transplantation, faecal bacteriotherapy is a medical procedure where stool from a healthy patient is transferred to that of a patient experiencing recurrent Clostridium difficile colitis. Clostridium difficile is a bacterium that causes intestinal infections and is notorious for being difficult to treat. The procedure aims to transfer healthy bacteria from the donor to the patient to restore a healthy microbial environment and therefore treat the disease. While this is disgusting and fascinating at the same time, please do not try this at home.

• The link between oral health and systemic/general health

Maintaining a healthy mouth is important for preventing oral diseases, including tooth decay and gum disease. Research has shown that taking care of our teeth and mouth has effects further away from the oral cavity. In fact, oral diseases, gum disease in particular, have been linked to several systemic diseases, including cardiovascular disease, rheumatoid arthritis, Alzheimers and diabetes.

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• It is estimated that we have as much as ten times more microbes in our bodies than human cells.

• Up to the late 18th century it was believed that dental decay/caries was caused by a tooth worm; nowadays we know it is due to sugar-digesting bacteria.

• Antonie van Leeuwenhoek, a Dutch scientist, was the first person to see bacteria using a microscope he built himself.

• In Amsterdam there is a whole museum dedicated to microbes called Micropia.

• Dr Barry Marshall confirmed that the bacterium Helicobacter pylori can cause stomach ulcers by drinking a broth infected with the bacterium.

• Scientists and medical professionals are currently researching the links between the gut microbiome and mental health.

For more trivia, see: www.um.edu.mt/think.

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