Definition and localization of the process
In pharmacology and clinical medicine, drug-induced dysbiosis refers to a pronounced disruption of the normal, evolutionarily established balance of microflora (microbiota). This pathological process unfolds predominantly on the surface of mucous membranes that are normally densely populated with beneficial microorganisms.
The main lesion loci where dysbiosis manifests most brightly:
- Mucous membrane of the gastrointestinal tract (GIT).
- Oral mucosa.
- Vaginal mucosa.
It is in these zones that the natural microflora performs crucial protective functions, the loss of which leads to serious clinical consequences.
Etiology: why the disturbance occurs
From the standpoint of etiology, the development of this adverse effect is directly related to ongoing drug therapy. Most often, the trigger is the intake of antimicrobial agents.
The greatest danger to the natural balance of the microbiota is posed by broad-spectrum antibiotics. Unlike narrowly targeted drugs, they do not possess high selectivity and have a detrimental effect not only on the target pathogen of the infection, but also on the patient's commensal (normal) flora.
Pathogenesis of drug-induced dysbiosis
The mechanism of development (pathogenesis) of dysbiosis against the background of antibiotic therapy is a sequential cascade of disorders. It can be divided into three key stages:
- Destruction of beneficial flora. Under the direct pharmacological action of the antibiotic, there is a massive death of beneficial microflora, which normally competes for nutrients and receptors on the mucous membranes.
- Suppression of defenses. The death of the normal microbiota inevitably entails a decrease in the local immunity of the mucous membranes, since beneficial bacteria play a critical role in maintaining it.
- Opportunistic infection. In the absence of competition and a decrease in immune surveillance, active, uncontrolled reproduction of opportunistic microflora begins. In particular, vacant ecological niches are rapidly occupied by yeast-like fungi of the genus Candida.
Treatment and Prevention
To minimize the consequences of antibiotic therapy and eliminate already arising dysbiosis, an integrated approach is used, including two main directions:
Etiotropic therapy Aimed at suppressing the proliferated opportunistic flora, primarily fungal. For this purpose, often simultaneously with a course of antibiotics, antifungal agents are prescribed. A classic example of such a drug is nystatin.
Restoration of normal flora After suppressing pathogens, it is necessary to artificially replenish the deficiency of beneficial bacteria on the mucous membranes. For this purpose, specialized drugs containing lyophilized (specially dried) live bacteria are used. The most well-known representatives of this group include:
- Bifidumbacterin
- Bifidum
Briefly: answers to topical questions
Which specific drugs are used to artificially replenish the deficiency of beneficial bacteria on the mucosa?
To restore the normal microflora of the mucous membranes, special microbiological preparations containing representatives of saprophytic flora are used. In medical practice, the following medications are used: bifidumbacterin, dry colibacterin, bifidokol, lactobacterin, bactisubtil, biosporin, gastropharm, linex forte, as well as a single-component sorbed bifidobacteria probiotic. These drugs are prescribed for the reimplantation of beneficial bacteria after a course of antibiotic sanitation, contributing to the full colonization of the intestine with eubiotic flora.
To which pharmacological group do preparations containing lyophilized live bacteria belong?
Preparations containing live lyophilized bacteria belong to the pharmacological group of probiotics or eubiotics, and also belong to the class of immunobiological agents. These products contain non-pathogenic microorganisms that are representatives of human normal microflora or antagonists of pathogenic agents. They are used to correct microbiocenosis, normalize the qualitative and quantitative composition of the microflora of mucous membranes, and also to maintain innate immunity factors.
What antifungal agents, besides nystatin, are used for the etiotropic therapy of candidiasis in dysbiosis?
In the cited sources, nystatin is directly indicated for the etiotropic therapy of candidiasis in drug-induced dysbiosis. Other antifungal agents are mentioned for specific clinical situations, but their use specifically in dysbiosis is not confirmed in the sources.
What is the mechanism of action of nystatin on yeast-like fungal cells?
In the sources, the mechanism of action is described for polyene antibiotics: they bind to ergosterol of the fungal membrane, form channels and pores in it, through which low-molecular-weight substances and ions escape, leading to the death of the fungal cell. Nystatin's belonging to polyene antibiotics is not explicitly stated in the cited sources.
What is the pharmacological difference between probiotics and prebiotics in microflora correction?
The pharmacological difference lies in the composition and mechanism of action on microbiocenosis. Probiotics are preparations containing living microorganisms (representatives of normoflora or self-eliminating antagonists) that directly colonize the intestine and exert a direct antagonistic effect on pathogens. Prebiotics are special substances that do not contain live bacteria, but serve as a nutrient medium and stimulator for the growth and reproduction of the body's own normal microflora.
The "Three P" rule for pathogenesis: Normal flora dies → Local immunity drops → Candida raises its head.
Class and exam questions
Which drugs most often cause drug-induced dysbiosis?
The main cause is antimicrobial agents, especially broad-spectrum antibiotics, because they destroy not only the disease pathogen, but also the beneficial flora of the mucosa.
Which opportunistic flora proliferates during dysbiosis?
When normal microflora is suppressed and local immunity decreases, active reproduction of Candida fungi most often occurs.
Why is nystatin prescribed along with antibiotics?
Nystatin is an antifungal agent. It is prescribed as part of etiotropic therapy to prevent or treat the overgrowth of Candida fungi during antibiotic use.
What else to study on this topic
- Mechanisms of action of broad-spectrum antibiotics on the microbiota
- Features of local immunity of mucous membranes (GIT, oral cavity, vagina)
- Pharmacodynamics of nystatin and other antifungal agents
- Bacterial lyophilization technology in drug manufacturing (bifidumbacterin)
- Pathogenic properties and virulence factors of Candida fungi
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