Different groups of antibiotics use different mechanisms to prevent bacterial growth and multiplication. Each antibiotic has a certain spectrum of activity and, if chosen adequately, is effective in treating bacterial infections. Besides their impact on bacteria, antibiotics also influence the human body in a way that can be desired (immunomodulatory effect) or undesired (various side effects).
Gastrointestinal side effects are the most common adverse effect and all antibiotics influence the suppression of certain components of intestinal microflora, depending on the activity spectrum, dosage, duration of therapy and method of administration. By destroying pathogenic microorganisms, an antibiotic simultaneously changes the microbiological diversity of intestinal microflora, thereby reducing the physiological defences of the organism.
Intestinal microflora has an influence on a range of physiological and pathophysiological mechanisms, it is a part of the process of digestion, development of immunity and protection from pathogen microorganisms. Its natural balance is of particular significance to health because intestinal microflora represents the first line of defence from external antigens that enter the body through the digestive system.
It has been shown that after the administration of antibiotics, there is a change in the type and number of bacteria in the stool. The amount of bacteria of the normal physiological flora, of the Bifidobacterium, Streptococcus and Lactobacillus genus, was decreasing, while, for example, the amount of Klebsielle and yeast increased.