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A modern look at the vaginal ecosystem.

Studies on this topic were started by Doderlein, who  in 1892 he described Gram-positive lactobacilli. The properties of lactobacilli were described in 1914 by Curtis, who discovered their dominant role in normal vaginal secretion. In 1938, Weinstein described the presence of anaerobes in the normal vaginal microflora in 93% of pregnant women and 90% of non-pregnant women.

The vaginal microflora depends on estrogen stimulation. These cause the vaginal cells to proliferate, increasing the glycogen content in them. they further promote cytolysis (in the presence of Lactobacilli) with the subsequent release of glycogen, which is cleaved in the presence of vaginal enzymes (glycogenolysis) into simple sugars - maltose and dextrose. Lactobacilli convert these simple sugars into lactic acid, which maintains an acidic environment in the vagina of pH 3.8-4.5.

Right from fluctuations in estrogen levels, the vaginal microflora changes. During pregnancy, the vagina of a woman's fetus is sterile. In the first 2-3 weeks of extrauterine life, the vaginal flora reflects the environment of adult women, it is caused by the transplacental transition of maternal estrogens during childbirth. This condition is temporary. We can find several Lactobacilli in girls before menarche, this is due to the low glycogen content in the vaginal epithelial intermediate cells. We can also encounter the following bacteria during this period:

Staphylococcus epidermidis (21%), Diphtheroides (21%), Bacteroides (19%), Peptococcus (19%), Porphyromonas (19%), Gardnerella vaginalis (12%) and also Candida fungi.

After menarche, the bacterial flora of the vagina is stimulated again with estrogens. In the postmenopausal period, the vaginal microflora resembles that of pre-adolescent girls.

In the vaginal environment of women of reproductive age we can find about 170 bacterial samples and fungi of the genus Candida:

Facultative and aerobic bacteria

Gram-positive bars

  • Lactobacillus spp.

  • Corynebacterium spp.

Gram-positive coca

  • Staphylococcus epidermidis

  • Staphylococcus aureus

  • Streptococcus agalactiae

  • Beta hemolytic Streptococcus

  • Other Streptococcus spp.

Gram-negative bars

  • Escherichia coli

  • Klebsiella spp.

  • Gardnerella vaginalis / 5-60% /

  • Proteus spp.

  • Anaerobic bacteria

Gram-positive coca

  • Peptococcus spp.

  • Porphyromonas spp. / Peptostreptococcus /

Gram-negative coca

  • Veilonella spp.

  • Gram-positive rods of Bifidobacterium spp.

  • Clostridium spp. Eubacterium spp. Propionibacterium spp.

Gram-negative bars

  • Prevotella spp. / Bacteroides /

  • Fusobacterium spp.

Mycoplasma

  • Ureaplasma urealyticum

  • Mycoplasma homonis

Fungi

  • Candida spp.

Thus, culture examinations of vaginal secretions do not have much diagnostic value for detecting vaginal microflora diseases.
It is found ev 1 gr. less than 107 bacteria are normally present in the vaginal tissue and the ratio of aerobic / anaerobic bacteria is 2: 5. Estrogens stimulate the vaginal bacterial flora mainly by increasing the concentration of glycogen in the intermediate bb. after you, o is a condition for colonization and reproduction of lactobacilli. Lactobacilli make up 96% of the normal vaginal flora in women during the reproductive period !!!.
All rods of the Lactobacillus strain are Gram-positive, do not produce spores or catalases, but produce lactic acid as a result of anaerobic glycogen metabolism (as mentioned above) and those other organic acids.
Lactobacillus strains are facultative bacteria that can grow in both aerobic and anaerobic environments. Individually, Lactobacilli differ in length and width and sometimes look like coca. The Lactobacillus strain includes 50 species of lactobacilli that colonize different parts of the vagina, e.g. Lactobacillus fornicalis is present in the posterior vaginal arch, while Lactobacillus acidophilus-vaginalis is in the vaginal vestibule. The following species are found in normal vaginal secretions:

Lactobacillus crispatus / 50% /, Lactobacillus jenseni / 23% /, Lactobacillus fornicalis / 15% /, and less often L. fermentum, L. gasseri, L. brevis and others. Controversial to previous views, Lactobacillus vaginalis is rarely present in the vaginal environment. / 0.3% / !!!

Lactic acid and other organic acids produced by lactobacilli cause a pH of 3.8-4.5 and are only part of the defense mechanisms against excessive bacterial growth. Later studies found that lactobacilli produced other substances that help maintain a normal vaginal ecosystem: protease inhibitors, endopeptidases, arginine deiminase (have a destructive effect on many bacteria), immunosuppressive proteins, lactocidine and hydrogen peroxide. Hydrogen peroxide produced by L. crispatus and L. jenseni is a toxin that inhibits the multiplication of bacteria, mainly anaerobic and sexually transmitted viruses.- Human Papilloma Virus and Human Immunodeficiency Virus. Certain species of vaginal bacteria produce other bacteriocins (macromolecular proteins) which, together with lactocidin, keep the yeast addressing the vaginal wall in a saprophytic and / or latent state.

The normal estrogen-stimulated vaginal ecosystem is determined by lactobacilli and their products (lactic acid, other organic acids, H2O2, endopeptidases, arginine deaminase, immunosuppressive proteins, protease inhibitors, lactocidin) and other aerobes and anaerobes and bacteriocins produced by some of them.

A similar ecosystem is found in the anterior 1/3 of the urethra. Lactobacilli colonizing the urethra prevent the adhesion of uropathogens to its epithelium.

ATB th, HA, IUD and those barrier contraception, application of vaginal tampons during canteens, vaginal irrigation or disinfection, smoking tobacco cause a disorder of the vaginal ecosystem that contributes to the development of bacterial vaginosis, vulvovaginal candidiasis and trichomoniasis. Bacterial vaginosis has a negative effect on the course of pregnancy, childbirth and the puerperium / PROM, premature birth, IU fetal death, inflammation after childbirth, inflammatory complications of the newborn /.

Attempts to correct the disease of the bacterial vaginal ecosystem through the application of probiotic preparations, e.g. lyophilized Lactobacillus rhamnosus (L. acidophilus) is inefficient and expensive. Lactobacillus cultures in vitro, contained in probiotics for current use, are not components of the vaginal flora and when applied to the vagina they unsuccessfully colonize its wall !!!

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