Bacteria is not always bad, especially when we are talking about our intestines. There are so many microorganisms in our gut, that scientists call this place a “microbiota”, which is an environment full of life. Bad bacteria can be harmful and cause disease especially in your poop, but some microbes can prevent certain diseases because they take up places bad bacteria can’t colonize when they are around. In this way, good bacteria prevent various gastrointestinal diseases, and even make it more difficult for pathogens to spread to the bloodstream.
Good bacteria in our gut is also called commensal bacteria, they feed and reproduce, but can live there without causing any disease. The same happens to our mouth and skin, there’s a lot of commensal bacteria, normal flora, that does not cause any particular disease. The only way good bacteria can cause disease is when patients suffer from severe immunodeficiency. Otherwise, it is easier to get sick from a greasy take-out food than normal gut flora. But be extra careful, there are a few things that affect normal flora in our gut and can cause serious problems.
When normal gut flora is not there, the really bad guys have open field to colonize and cause disease. Additionally, not having a healthy balance in our gut microbiota can lead to several ailments, not only in the gastrointestinal system. For example, the normal intestinal flora is in charge of modulating the entire immune system, and changes in gut flora can affect how we react towards disease and allergy. Some studies have also linked unbalanced gut flora with obesity, Alzheimer’s disease, and other entities. Let us go through 3 of the most common reasons why gut flora may be compromised, and discuss the symptoms they may cause.
Severe infections can reduce good bacteria colonization
Good bacteria can replace bad bacteria and prevent them from colonizing the gut, but it can also happen all the way around. When there’s a severe gastrointestinal infection, pathogens can multiply excessively and slowly take over. One clear example is Escherichia coli. This bacterium is a normal colonizer of the human intestines, and makes up a part of the normal microbiota. However, some resistant strains of Escherichia coli can cause an widespread colonization throughout the colon, and take up the place of normal bacteria. This happens especially on immunosuppressed patients, and in the face of certain strains of Escherichia coli that cause more disease than others.
When this problem becomes out of control, harmful bacteria can even reach the bloodstream and trigger a deadly condition called bacteremia. Bacteremia is basically a spread of bacteria through the blood vessels, but even before reaching that state, an overgrowth of Escherichia coli can cause diarrhea, blood in the stools, fever, abdominal cramps, and in some cases an overinfection with another bacterium named Shigella dysenteriae.
Diarrhea washes away good bacteria
The opposite of constipation, Diarrhea acts the same way as flood water washes away debris from the streets, and sometimes even cars and people, diarrhea can take out most of the good bacteria from the intestinal lining. It is not difficult to explain, and in fact, this is one of the reasons bacteria appears in the first place. Is an attempt of our body to defend from infectious foes, but takes away in the process good bacteria as well. Since commensal bacteria does not have the rapid growth pathogenic bacteria has, this leads to colonization and worsening of the symptoms. In these cases, diarrhea will continue as long as there’s not enough good bacteria in your gut or that of children. So, it’s a vicious cycle that grows uncontrollably until we introduce new probiotic strains to our system.
Antibiotics kill together good and bad bacteria
Antibiotics are another common reason why good bacteria are reduced because they do not make a difference between good and bad microorganisms. Antibiotics attack them all. This happens when patients take antibiotics without any restraint, during a very prolonged treatment, or high doses of antibiotics.
In these cases, it is common to see good bacteria get affected, and patients may start to notice a sudden change in their stools. In some cases, we don’t get watery diarrhea but only softer stools, but in certain cases the swipe is more severe and severe diarrhea with dehydration may start. There are certain probiotic strains that are very good after taking antibiotics, precisely because they restore the normal gut microbiota and get things back to normal.
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Dethlefsen, L., & Relman, D. A. (2011). Incomplete recovery and individualized responses of the human distal gut microbiota to repeated antibiotic perturbation. Proceedings of the National Academy of Sciences, 108(Supplement 1), 4554-4561.