In the near future doctors may routinely treat some illnesses with beneficial microbes called probiotics, rather than prescribing antibiotics or other common medicines. This is the exciting possibility that researchers are now exploring for a variety of illnesses and conditions, such as urinary tract infections, acne, and sinus infections.
For many years health providers have viewed all bacteria and microbes as germs, as something to eliminate. Some illnesses and infections are routinely treated with antibiotics to kill bacteria. Think of all the times we say “I’m going to see a doctor to get antibiotics”.
However, the development of new technologies (e.g. genetic sequencing) in the last two decades has resulted in the discovery of a whole new world of multitudes of microbes that live in people. This is changing medical views in how to be healthy and how to treat illnesses.
The microbes in our bodies
Humans are amazingly complex organisms. Not only are we made up of human cells, but also trillions of microbes (bacteria, fungi, viruses) that live in communities both within and on us. This is called the human microbiome or human microbiota. The combined weight of all these tiny microbes, all the thousands of species, adds up to about 2.5 pounds of weight in an adult.
Each of us has more microbes than human cells! All these microbes play essential roles in our daily functioning – such as getting nutrients and energy from food, interacting with our immune system, and protecting us from harmful pathogens. In other words, don’t think of these microbes as harmful “germs”, but as beneficial and needed – as partners with our human cells.
Normally all the microbes coexist in balance and harmony, but imbalances can occur – for example, from infections, a poor diet or lifestyle, allergies, environmental toxins, or even certain medicines such as antibiotics. An out-of-balance microbial community is called dysbiosis. Researchers have now linked disturbances within our microbial communities to a variety of diseases.
Microbiomes are different in health and illness
Healthy individuals and people with illnesses have differences in their microbiomes, with a mix of microbes that is almost like a signature or microbial fingerprint. Depending on the illness or condition, there are more of some species, less of others, some species added, and some missing. The presence of some microbes (e.g. Faecalibacterium prausnitzii) are consistently associated with good health, while others are associated with poor metabolic health and disease.
Wherever we look we see these differences. For example, the microbiomes are different in healthy skin as compared to skin with acne or eczema, in healthy sinuses compared to those with chronic sinusitis, in women with and without bacterial vaginosis, and in a healthy gut as compared to a person with diabetes, heart disease, or intestinal bowel disease (IBD).
Treating illnesses with beneficial bacteria
Researchers are looking at ways to improve the microbiome in these and many other conditions, which may mean alterations in a person’s diet and lifestyle, or by using beneficial bacteria.
The thinking is that beneficial bacterial species or probiotics would dominate over and suppress pathogenic (harmful) species, and somehow restore balance to whatever microbial community in the body shows imbalance. Think of it as restoring health by microbial rebalancing. The field is still in its infancy, but there have already been successes.
Fecal microbiota transplants (commonly known as fecal transplants or stool transplants) have had spectacular success in treating people with recurring Clostridium difficile infections, which can cause severe diarrhea and life-threatening inflammation of the colon. In this simple procedure an entire microbial community (the stool) from the healthy donor is transplanted into a sick person. Deathly ill people hospitalized with C. difficile infections have walked out of hospitals feeling well within days of a transplant from a healthy donor.
Other examples of success stories include treating bacterial vaginosis (BV) with a mix of beneficial bacteria, including Lactobacillus crispatus. The bacteria Lactobacillus sakei has been effective for many people with chronic sinusitis. Different bacterial species are being tested for many conditions, such as eczema, allergies, wounds, periodontitis, even depression and anxiety. Many treatments or ”bacteriotherapy” involve restoring missing or depleted bacteria that normally occur in a healthy person.
A role for probiotics in cancer treatments?
Giving specific microbes may even become part of some cancer treatments! Immunotherapy is an exciting development in metastatic cancer treatment because it may result in tumors totally disappearing. It is a treatment that uses a person’s own immune system to fight cancer, but unfortunately it only works for a minority of cancer patients. It turns out that the composition of a person's gut microbiome influences whether a person responds to immunotherapy drugs.
In a recent study fecal transplants were given to persons with advanced melanoma (who had not responded to immunotherapy drugs) from a donor who had responded well to immunotherapy drugs. An amazing result was that 40% of the recipients had gut microbiome changes that resulted in the immunotherapy drug now working against their melanoma. Future studies will try to identify which specific microbes are the ones that were critical for overcoming a tumor's resistance to immunotherapy drugs.