Prevention Strategy of Urogenital Infections by Using Lactobacilli with Probiotic Properties

Abstract

Lactic acid bacteria (LAB) constitute a group of Gram-positive nonsporing nonrespiring bacteria, cocci or rods, that produce lactic acid as the major end product during the fermentation of carbohydrates. The term LAB is associated with bacteria involved in food fermentation and bacteria normally associated with the mucosal surfaces of human and animals. The classification of lactic acid bacteria into different genera is based on morphology, mode of glucose fermentation, growth at different temperatures, configuration of the lactic acid produced, ability to grow at high salt concentrations, and acid or alkaline tolerance (Pascual, 2004). Bacteria belonging to the genus Lactobacillus are considered to be the main LAB and the predominant microorganisms in the gastrointestinal and urogenital tracts of humans as well as homeotermic animals. They are also used for elaborating different fermented foods categorized as GRAS (generally considered as safe). Although there are data on simultaneous colonization of the human vagina by two different species of Lactobacillus, which can be homofermentative, heterofermentative or a combination of both (Kaewsrichan et al., 2006; Pascual et al, 2006), only one species has been isolated from the vaginal tract. Also, there are evidences of their effectivity in the prevention of urogenital infections (Pascual, 2004; Axelsson, 2004). The urogenital microbiota of a healthy woman comprises approximately 50 species of organisms, witch differ in composition according to reproductive stages and exposure to several factors, including antibiotics and spermicides (Pascual, 2004). In the complex vaginal environment, bacteria of the lactobacilli group (107–108 CFU g-1 of vaginal fluid) are the dominant microorganisms in healthy pre-menopausal women, and play an important protective role by limiting growth of pathogenic microorganisms. When lactobacilli are reduced, eliminated, or replaced by pathogenic species, the host has an increased susceptibility to urinary tract infections (UTIs), genital tract infections (GTIs), bacterial vaginosis (BV), vulvovaginal candidiasis (VVC), and infection by Neisseria gonorrhoeae or Trichomonas vaginalis. Worldwide studies of UTIs or GTIs have revealed increasing antibiotic resistance among pathogenic microorganisms. Our research group has isolated human vaginal lactobacilli, selecting those with beneficial or probiotic properties (Czaja et al., 2007).