Bacterial vaginosis

Clinical and laboratory diagnostics

To establish an accurate diagnosis, specialists rely on clear criteria. The most important sign is the microscopic picture: there is a complete absence of pronounced leukocytosis in the smear, which distinguishes this process from classical inflammation. At the same time, a change in acidity is recorded: the pH of the vaginal discharge exceeds 4.5.

A special place is occupied by the aminotest. The essence of the method is to add a 10% potassium hydroxide (KOH) solution to the discharge. The reaction is considered positive if a sharp intensification of a specific "fishy" odor appears.

Additional methods such as polymerase chain reaction (PCR), ELISA, direct immunofluorescence (DIF), or bacteriological culture are used quite rarely. The main rule when using them is a strict quantitative assessment of the detected microorganisms. The fact is that the pathogen Gardnerella vaginalis in low titers is part of the normal microflora. Only a high concentration of bacteria is of diagnostic significance.

Therapeutic tactics

Combating the disease is based on the principles of a comprehensive approach. The physician must provide etiotropic, pathogenetic, and symptomatic effects.

• First stage (antibacterial): Pathogens demonstrate susceptibility to penicillins, lincomycin, clindamycin, and vancomycin. However, the absolute drugs of choice are representatives of the nitroimidazole group (primarily metronidazole).
• Second stage (restorative): After completing the course of antibiotics, probiotics (e.g., acylact or lactobacterin) are necessarily prescribed. They are essential for restoring the natural vaginal biocenosis.

Specific prophylaxis (vaccines) has not been developed to date.

Characteristics of bacteria of the genus Mobiluncus

The genus Mobiluncus (main species are M. curtisi and M. mulieris) actively participates in the development of vaginosis as associated bacteria during excessive proliferation.

Morphology and physiology: These are thin, curved rods with tapered ends (size 0.4–0.6 × 1.2–4.0 µm) that do not form spores, but are motile due to lateral or subpolar flagella. In smears, they are located singly or in pairs, resembling "seagull wings." Although their cell wall structure is characteristic of Gram-positive microorganisms, they stain gram-variable.

Cultural properties:

• Respiration type: Obligate anaerobes. They have extremely low resistance and die instantly in the air.
• Cultivation: They grow only on complex nutrient media at a temperature of 37 °C, forming smooth, transparent, and colorless colonies.
• Biochemistry: Fermentative metabolism (ferment glucose). Catalase, indole, and oxidase tests are strictly negative.

Class and exam questions

What else to study on this topic

• Detailed characterization of the morphology and biochemical properties of Gardnerella vaginalis
• Mechanism of action of metronidazole on obligate anaerobes
• Features of biomaterial collection for performing the aminotest
• Composition of complex nutrient media for successful cultivation of the genus Mobiluncus
• The role of normal microflora in maintaining vaginal acidity

Other topics from the section 'Spirochetes and spiral bacteria (Treponemes/syphilis, Borrelia/Lyme disease and relapsing fevers, Leptospira, Campylobacters, Helicobacters)'

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