Vaginal dysbiosis

Essence of the pathological process

Infectious diseases of the vagina are the most common pathology in patients of reproductive age. Globally, they are classified into several main types: bacterial vaginosis, non-specific vaginitis, vaginal candidiasis, and trichomonal vaginitis.

Any infectious lesion begins with the adhesion of opportunistic microorganisms to the epithelium. They then actively proliferate, forming vaginal dysbiosis. If the infectious agents overcome the protective barriers, inflammation develops—vaginitis.

However, the most common form of dysbiosis — bacterial vaginosis (BV) — is specifically a non-inflammatory clinical syndrome. It is detected in 21–33% of women of reproductive age. It is important to understand that BV is not considered a sexually transmitted infection (STI). Previously, this condition was called "gardnerellosis", but today it has been proven that Gardnerella vaginalis is an integral part of the normal microflora, and the problem lies in the disruption of the entire vaginal microecology.

Microbiological and biochemical changes

In dysbiosis, both the qualitative and quantitative composition of the microflora changes with a sharp increase in the total bacterial concentration. G. vaginalis transitions from the status of a safe commensal to a pathogen.

The mechanism of development includes three stages:

1. The number of lactobacilli, which normally dominate and protect the vagina, decreases sharply or they disappear entirely.
2. Rapid colonization by G. vaginalis occurs—its titers rise to colossal values ($10^{10}$–$10^{12}$ CFU/ml).
3. A microbial association is formed. There is a predominant growth of obligate anaerobes (Bacteroides spp., Prevotella spp., Peptostrupococcus spp., Mobiluncus spp., Fusobacterium spp.) and Mycoplasma hominis.

These microbiological shifts entail biochemical changes. Normally, the pH of the vaginal contents is 4.5, but in dysbiosis, the environment becomes alkaline—shifting to 7.0–7.5. In addition, anaerobes begin to produce volatile amines, which cause the specific foul fishy odor.

Triggers and predisposing factors

Dysbiosis does not arise out of nowhere. Various triggers contribute to the transition of opportunistic flora into an aggressive state:

• Systemic factors: pregnancy, menopause, diabetes mellitus, as well as severe stress.
• Iatrogenic causes: use of antibacterial drugs (including systemic antibiotics), oral contraceptives, intrauterine contraceptives (IUCs), treatment with hormonal drugs or immunosuppressants.
• Local factors: history of inflammatory diseases of the genital organs, decreased local immunity, frequent change of sexual partners.

Hormonal disorders accompanied by the clinical picture of oligomenorrhea and opsomenorrhea also predispose to the development of the disease. All these factors disrupt the functioning of natural biological barriers.

Clinical presentation and diagnostic approaches

The main complaint of patients with bacterial vaginosis is profuse, homogeneous, creamy, gray vaginal discharge. They characteristically adhere to the vaginal walls and have an unpleasant "fishy" odor. Sometimes additional symptoms may join: itching, burning in the vaginal area, and discomfort during intercourse.

The main diagnostic method is microscopy of Gram-stained vaginal smears. They reveal "clue cells"—desquamated vaginal epithelial cells densely coated with bacteria.

Important nuance for pregnant women: since vaginal dysbiosis creates prerequisites for infectious processes and is a risk factor for ascending infection, pregnant women with BV are strictly indicated for local antibacterial treatment. The main goal is the prevention of urinary tract infection (level of recommendation evidence A, high certainty).

Class and exam questions

What else to study on this topic

• Bartholinitis: stages of development of a greater vestibular gland abscess.
• Surgical treatment of bartholinitis: marsupialization technique.
• Non-specific vaginitis: differences between the inflammatory process and dysbiosis.
• Vaginal candidiasis and trichomonal vaginitis: features of the clinical presentation.
• Mechanisms of adhesion of opportunistic microorganisms to epithelial cells.

Other topics in the "Gynecology" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.