Doderlein's lactobacilli owe their name to their discoverer, Albert Doderlein, a German obstetrician who in 1892 identified and described the salient features of these bacteria. Today we know that the Doderlein lactobacilli belong mainly to the Lactobacillus acidophilus species, the same exploited in the production of some of the hyper-advertised "probiotic-rich yoghurts to drink".
Under normal conditions, during fertile age, the Doderlein lactobacilli represent about 90% of the total vaginal microorganisms . These bacteria are particularly useful for maintaining the health conditions of this delicate region, which they protect through various mechanisms. The most important feature is their ability to metabolize the glycogen present in the vaginal transudate producing lactic acid. The result is a decrease in pH (<4.5): this acidity constitutes an important defense of the vaginal environment against the attacks of pathogenic germs.
The presence of estrogens significantly influences the amount of glycogen available to Doderlein's lactobacilli: when the concentrations of these hormones are particularly low, as in the first periods of life until adolescence, but also during menopause, the availability of glycogen decreases and this limits the proliferation of lactobacilli: the vaginal pH increases and with it the susceptibility to infections from pathogens (especially of intestinal origin).
The vaginal colonization by the lactobacilli of Doderlein occurs at birth, during the passage in the birth canal due to the diffusion of microorganisms coming from the vaginal maternal environment; in the first days of life, the residual presence of placental production of estrogen favors the rapid multiplication of Doderlein lactobacilli, thanks to the high glycogen content of the vaginal mucosa.
In addition to acidification of the vaginal environment, the Doderlein lactobacilli protect this area from pathogens also through a mechanism of biological competition for nourishment and for mucosal adhesion sites. Furthermore, they synthesize hydrogen peroxide (hydrogen peroxide) and other broad-spectrum antimicrobial agents.
The integration of the vaginal flora with Doderlein lactobacilli, through local applications, represents a valid therapeutic option in the presence of bacterial vaginitis. Among the various lactobacilli strains, the most suitable for this purpose seem to be those producing hydrogen peroxide. Oral supplementation seems to be less effective for this purpose, although it has an important preventive role due to the effect on the intestinal level, where it reduces the proliferation of pathogens (such as Candida albicans ) that could alter the normal vaginal flora. These practices should become common in association with the antimicrobial treatments used in vaginal diseases, which risk - even decimating the flora of Doderlein - to make the disease chronic. For the same reason, the restoration of the vaginal bacterial flora assumes the same importance as the reintegration of the intestinal one after prolonged antibiotic therapy; it should therefore take place, especially in women who are more sensitive to bacterial vaginitis, every time an antibiotic therapy is prescribed (for any disease, for example for the treatment of bronchitis).
Among the main enemies of Doderlein's lactobacilli, in addition to chronic estrogen deficiency, we recall the use of spermicides as contraceptive means (eg Nonoxynol-9), unprotected sexual intercourse, oral contraceptive use, therapies antibiotics, the use of colored synthetic underwear, excess of intimate hygiene.
