Bacteria are all around us – and inside of us – says colorectal surgeon Dr. Jaswant Madhavan. For those who have been hearing the chatter about probiotics, antibiotics and how gut bacteria influences overall health, Madhavan sorts out fact from fiction and tells us about studies that could shape the future of medicine.
How do bacteria affect our daily lives? What is the difference between “good” and “bad” bacteria? Why are they important?
What you see in the mirror is only part of you. There are about 10 times as many living organisms in your body as cells that make up your human body. The Human Microbiome Project, an NIH-funded project, seeks to identify and map these various organisms that live within us. We have bacteria living all over and inside us. The gut is teeming with micro-organisms. The total weight of these bacteria and viruses is about three to four pounds. That’s what an average brain weighs! In other words – and this is going to really hurt all those mysophobes out there – you are but a large vessel that breeds trillions of bacteria and helps in their propagation.
The organisms that live within us are a part of us. Until recently, their role in our existence has been poorly understood. There are still many of them that have not been identified, and a lot of them have never been grown in the lab. We are a fine symphony, in perfect balance between the trillions of bacteria that live within us and the cells that make up the human body. Most of the bacteria in the gut are found in the colon. In the gut, as elsewhere in the body, the bacteria are not merely commensal in nature, two organisms living together with no harmful effects on the other, but more of a symbiotic relationship in which the gut provides the bacteria with nutrients, and the bacteria in turn help in digesting food, improving the immune system and keeping harmful bacteria under control. Pathogenic bacteria, those that cause disease, are also seen as “normal” organisms within the gut. Their harmful effects and proliferation to disease-causing volumes are stymied by the large volumes of “good” bacteria. Skin bacteria live either on or in the superficial layers of the skin. They are commonly seen in the oil- and sweat-producing glands. Human sweat is non-odorous until acted upon by the bacteria, resulting in body odor. The bacteria live on oil produced by the glands. The “bad” bacteria are responsible for acne and other skin conditions. These bacteria, too, live in the skin normally, but an alteration in the balance between the good and the bad, for whatever reason, results in the excessive proliferation of these bacteria, leading to disease.
Recent scientific studies have shown possible links between intestinal bacteria and brain chemistry, Is this important to study further? Has this affected your recommendations as a physician?
Some of the bacteria in the gut actually produce substances that are usually associated with the brain and the nervous system. These are called neurotransmitters. Some of them, when released, elicit a feeling of well-being, whereas others help in deadening pain. It was found that when gut microbes from easy-going, adventurous mice were transplanted into the guts of timid and anxious mice they became more adventurous. In other words, these bacteria helped in modifying the behavior of the mice. In the future, a visit to your Primary Care Physician may result in you receiving a pill that was created using bacteria that were found in the gut. As they say, “It’s all in the guts!”
How do antibiotics work? Do they affect “good” bacteria?
As mentioned earlier, the human body with its trillions of micro-organisms is in a beautiful dance to a silent tune. When pathogenic bacteria rear their heads, this dance is disrupted. Antibiotics endeavor to destroy the pathogenic bacteria. Unfortunately, antibiotics are not aimed specifically at the pathogenic bacteria and, in most instances, take a shotgun approach, killing a number of good bacteria at the same time. This results in an imbalance within the body. Most of the time, the gut is repopulated by the micro-organisms from your immediate surroundings. Now, if you were at home, that would probably be fine, but this can present a problem if you’re in an area with organisms that are undesirable, such as a hospital. This results in a change in your biome, and not always for the good. It may take months before you regain your natural biome once you return home.
What are probiotics? Do they work? Are some kinds better/more effective than others? To what types of patients do you recommend them?
Probiotics are live micro-organisms that are usually consumed by mouth and are either the same as or similar to the micro-organisms in the body. Their beneficial effect has yet to be demonstrated in a consistent, clinical way. There is a lot of anecdotal evidence of some of them working to treat certain conditions or symptoms. Unfortunately, in most cases, their efficacy across a population for a particular disease condition is lacking. They are usually considered a safe supplement, but they are not usually recommended in people who are immunocompromised or even living with an immunocompromised person in their household. Probiotics’ safety in the very young has not been demonstrated.
Some of the probiotics have been studied and some of them have been found to have a more consistent number of micro-organisms in them. Others have shown large fluctuations of the organisms between batches. Probiotics from reputable companies are usually a lot more consistent than those of a generic nature. Probiotics are usually recommended for people on long-term antibiotics and to those with antibiotic-associated diarrhea. They are also widely used in patients with irritable bowel syndrome, although, as in most cases, their effects are not consistent.
How can I get more “good” bacteria? Can yogurt help the digestive tract?
The question of the human biome is still being studied, and we are nowhere near the end of our research. The human biome is like a person’s fingerprint in that no two people will have the same biome. So what is good for one may not have any effect in another or, rarely, may prove detrimental. Following a diet high in green leafy vegetables is more likely to populate your gut with good bacteria than is eating yogurt.
As far as yogurt is concerned, there are very few independent studies to prove its worth. Most studies that have been done were sponsored or conducted by the manufacturers themselves. And the beneficial effects touted are usually seen only on consumption of large amounts of yogurt rather than the small amounts most people consume on a daily basis. Bear in mind that there is a reason why the stomach has very few bacteria: they are all destroyed by the acid in the stomach. The majority of the bacteria consumed by mouth are killed in the stomach, though studies have shown that some of the lactobacilli make it into stool.
So you start off with a product where the number or quantity of bacteria is not known and almost certainly varies widely from batch to batch, and then consume a quantity of the product far smaller than was studied – which the manufacturer conveniently forgets to mention – and, finally, kill off most of the bacteria in the stomach, leaving you with, effectively, a placebo.
What is C. diff? How do people get it? What types of treatments are currently available for it?
Clostridium difficile is a spore-forming bacterium that is a normal denizen of the colon. Its pathogenic effects, which are due to toxins, are kept in check by the other bacteria in the colon. When these good bacteria have been destroyed by antibiotics, the C. diff bacteria no longer have anything to keep their numbers under control, and they then cause diarrhea, usually manifested as a condition called pseudomembranous colitis. If left untreated, it can progress to a very sudden and dangerous dilatation of the colon that can result quickly in death if not treated appropriately. There has also been an increase in community-acquired C. diff colitis with the increased use of medications to suppress stomach acid.
The treatment of C. diff infection at present is more antibiotics. It is usually treated with a metronidazole and failing that, oral vancomycin. A newer antibiotic now available for the treatment of C. diff infection is called Fidaxomycin. There is some evidence that certain probiotics can help in prevention of recurrences that occur in about 20 percent of patients. A novel method of treatment, which at present is available only at a few research centers, is that of stool transplantation. Stool from a healthy donor is placed in the colon of the diseased individual. It has proven to be 90 percent effective in control in cases of the disease where the usual antibiotics have not worked.
Dr. Jaswant Madhavan
Jaswant Madhavan, MD, is a board certified in colorectal surgery and has worked with Mount Carmel Health System and Colon and Rectal Surgery, Inc. for more than a decade. He is the past president of the Columbus Surgical Society and the Ohio Valley Society of Colon and Rectal Surgeons. Madhavan has more than 25 years of surgical experience and is a member of the teaching faculty of Mount Carmel’s residency program in colon and rectal surgery. He is also a fellow of the American College of Surgeons and the American Society of Colon and Rectal Surgery, and member of the American Association of Physicians of Indian Origin.
Madhavan completed residentcy training at Memorial Health University Medical Center in Savannah, Ga. and Grant Medical Center. He also underwent training at multiple institutions in the United Kingdom and India.
