Causes of vaginal microflora disorders

Inflammatory diseases of the female genital organs occupy the first place (55-70%) in the structure of gynecological morbidity. A significant share of them are infections of the vulva, vagina and cervix. In women of reproductive age, vaginitis develops as a result of bacterial infection (40-50%), vulvovaginal candidiasis (20-25%) and trichomoniasis (10-15%).

All inflammatory processes of the genitals are divided into non-specific and those caused by sexually transmitted infections.

Vaginal discharge examination plays an important role in diagnostics of inflammatory diseases of the lower genital organs. General signs of the inflammatory process are the appearance of leukocytes (neutrophils and eosinophils), lymphoid elements and macrophages.

Non-specific vaginitis is an infectious and inflammatory disease of the vagina caused by opportunistic microorganisms (E. coli, streptococci, staphylococci, etc.). In non-specific vaginitis, smears contain a large number of leukocytes (30-60 or more in the field of view), key cells are absent, but there are quite a lot of cells of the desquamated epithelium of the vagina. As a rule, several types of microorganisms are detected. In general, the microscopic picture is characteristic of inflammatory exudate.

Bacterial vaginosis is a non-specific (similar to inflammatory) process in which no pathogenic agents are found in vaginal discharge (it accounts for 40-50% of all infectious vaginitis). Currently, bacterial vaginosis is considered a vaginal dysbacteriosis, which is based on a violation of the microbiocenosis.

The most informative laboratory method for diagnosing bacterial vaginosis is the detection of clue cells (exfoliated vaginal cells covered with a large number of small gram-negative bacteria) in Gram-stained smears. These cells are found in 94.2% of patients, while they are absent in healthy women. The most objective method for identifying clue cells is the study of the cellular edges of the epithelium. Epithelial cells with blurred edges, indistinctly distinguishable due to the attachment of bacteria to them, are considered clue cells. In addition to clue cells, the presence of small bacteria in the absence of lactobacilli in microscopy with a saline solution indicates bacterial vaginosis.

The number of various facultative (Gardnerella vaginalis) and anaerobic (bacteroides) bacteria in bacterial vaginosis is higher than in healthy women. In fact, the total bacterial count in the vagina increases to 10 ¹¹ in 1 ml. Unlike patients with normal microflora, in patients with bacterial vaginosis, anaerobic rather than facultative lactobacilli predominate. A decrease in the number of facultative lactobacilli leads to a decrease in lactic acid formation and an increase in pH. In patients with bacterial vaginosis, the vaginal pH is within 5-7.5.

Gardnerella vaginalis (detected in 71-92% of patients, makes up more than 5% of all microflora representatives) and other anaerobes contribute to the intensification of the processes of rejection of epithelial cells, especially in alkaline environments, which leads to the formation of pathognomonic clue cells.

Due to the increase in the number of facultative anaerobes in bacterial vaginosis, the production of abnormal amines increases. With an increase in vaginal pH, amines become volatile, causing the typical "fishy odor" of vaginal discharge. To detect it, an amino test is performed in the laboratory (a specific odor appears when a 10% solution of potassium hydroxide is added to a drop of vaginal secretion).

When staining smears according to Gram, in patients with bacterial vaginosis, less than 5 lactobacilli and more than 5 gardnerella or other microorganisms are found in the immersion field. The presence of a large number of leukocytes in vaginal smears is not considered characteristic of bacterial vaginosis.

The criteria for diagnosing bacterial vaginosis are as follows.

• Positive amino test.
• pH of vaginal discharge >4.5.
• Key cells in Gram-stained smears.

Trichomoniasis is a specific inflammatory disease of the female genital organs (it accounts for 15-20% of all infectious vaginitis). Trichomoniasis diagnostics is based on bacterioscopic detection of vaginal trichomonads after staining smears with Gram, Romanovsky-Giemsa, methylene blue, or in native preparations (trichomoniasis is characterized by an oval or round shape, the presence of flagella and jerky movements). Constant identification morphological signs of vaginal trichomonads in smears are a characteristic, intensely colored, eccentrically located nucleus and delicate cellular cytoplasm. It should be noted that microscopic examination does not always immediately reveal trichomonads (the sensitivity of the method is 40-80%). Therefore, it is necessary to take material for examination again. Due to the inflammatory process, epithelial cells of various sizes, cells with an enlarged nucleus, binuclear cellular elements, focal accumulations of leukocytes in the form of a "cannonball" on the surface of the squamous epithelium are found in smears. The best results are obtained by viewing a native preparation under a microscope with a dark-field condenser, since this reveals single and weakly mobile individuals in clusters of cellular elements due to the clearly visible movement of flagella. When examining native preparations, one should remember the possibility of detecting, especially in urine, flagellated protozoa of the Bodonidae family. Unlike trichomonads, they are smaller in size and have only 2 flagella, which causes their rapid, progressive movement in a straight line. When examining stained smears, errors are possible, since epithelial cells can be mistaken for trichomonads.

Outpatient observation with examination of urine and vaginal discharge in women who have had trichomoniasis should be carried out for at least two menstrual cycles.

Gonorrhea. When examining vaginal smears, gonorrhea is characterized by the intracellular location of gonococci (in leukocytes), their bean-shaped form and negative staining according to Gram.

Genital candidiasis is caused by yeast-like fungi of the genus Candida (it accounts for 20-25% of all infectious vaginitis). To diagnose candidiasis, a microscopic examination of the material taken from the lesion is performed (the sensitivity of the method is 40-60%). In case of genital candidiasis in the acute period of the disease, lactobacilli are found in the vaginal discharge in insignificant quantities (on average - 16.6% of the entire microflora) or they are absent altogether. In 75% of patients, the vaginal pH is within 5-5.5, which is considered very informative for diagnosing candidiasis. The presence of mycelium and spores in wet smears treated with a 10% potassium hydroxide solution confirms the diagnosis.

Results of the study of vaginal discharge in various diseases

Research results	Bacterial vaginosis	Trichomoniasis	Candidiasis
RN	>4.5	>4.5	4.0-4.5
Wet mount microscopy (secretions from the lateral wall of the vagina, diluted in 0.9% sodium chloride solution)	Key cells	Motile flagellated protozoa (detected in 40-80% of cases)	Pseudohyphae (found in 40-60%)
Microscopy of a Gram-stained smear (discharge from the lateral wall of the vagina)	Key cells		Spores/pseudohyphae (found in 40-60% of cases)
Amino test	Positive	Usually positive	Negative

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