Bacterial flora

Bacterial flora , a set of microorganisms that are usually found as saprophytes on the skin , intestine , mouth and vagina ; contributes to maintaining the state of health of the host (protection against other infections, maintenance of a certain pH , secretion of vitamins or other nutritional requirements for the host, etc.). Only under specific conditions do they act as pathogens .


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  • 1 General
  • 2 The intestinal bacterial flora
  • 3 Flora as a cause of disease
  • 4 Objectives
  • 5 sources


The bacterial flora is generally associated with that located in the gastrointestinal tract , but in reality it also inhabits other organs and systems , such as the skin, the respiratory tract , the vagina and the ear . The bacterial flora is acquired immediately after birth. Initially, various aerobic genera colonize the digestive tract , especially Enterobacteriaceae such as Escherichia coli and also various species of the genus Lactobacillus . They consume oxygenfrom the environment and, progressively, a microsystem is established in which there is an overwhelming predominance of obligate anaerobic species, especially Bacteroides , Clostridia , Eubacteria and Bifidobacteria . At 2 years of age, the established flora is practically definitive, as it is usually very stable throughout the life of the individual.

The intestinal bacterial flora

The intestinal flora is made up of more than 3 million bacteria. When we use antibiotics , this flora disappears since these drugs not only kill pathogenic bacteria, but also the beneficial bacteria that are part of the flora. When it comes to maintaining good health, it is very important to protect and increase this beneficial flora and it is precisely through food that we can contribute to it.

Some foods called “ prebiotics ” help the intestinal flora to grow, which means that we need to feed these beneficial bacteria so that they can proliferate. Soluble fiber, found in foods like fruits and vegetables , serves as food for these bacteria.

There are also the so-called ” probiotics ” which are foods that contain some of the microorganisms typical of the intestinal flora, such as lactobacilli and bifidobacteria . These probiotics can be found in foods such as yogurt and jocoque .

The function of the bacterial flora is:

  • Defend the colon area from the settlement of pathogenic species of bacteria.
  • Break down food residues that have not yet been fully digested.
  • Produce some vitamins like B2 , B6 , B12 and K.
  • Maintain the optimal environment for the proper functioning of the intestinal immune system.
  • Control the cholesterol in the area.

Flora as a cause of disease

Some elements of the flora or their activities can be the cause of diseases for the host in certain circumstances. Bacterial translocation is the passage of viable bacteria through the epithelium of the gastrointestinal mucosa. After crossing the barrier, the bacteria can migrate through the lymph and reach extraintestinal locations, such as the mesenteric ganglia , liver , or spleen . If the bacteria manage to spread through the bloodstream in sufficient numbers, they can cause very serious conditions, such as sepsis ., multi-organ failure and death. The overgrowth of some species, such as Clostridium difficile, can be the cause of serious conditions, such as pseudomembranous colitis.


These bacteria aim to take care of the integrity of our body, by preventing pathogenic bacteria -that is, those that cause disease- from staying in our body and causing us an infection. In the same way , the bacterial flora contributes to the production of some vitamins such as those of the B complex and vitamin K. It has also recently been associated as a protective agent in the development of allergies and is known to help activate the immune system.


by Abdullah Sam
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