Is there a role for lactobacilli in prevention of urogenital and intestinal infections?

This review describes the importance of microbial adhesion in the ecology of the urogenital and intestinal tracts and the influence of host and microbial factors in bacterial interference. In a recent revival of interest in bacterial interference, lactobacillus administration has been studied as a means of treating and preventing disease. Although evidence is conflicting, Lactobacillus acidophilus appears to be involved in beneficial antagonistic and cooperative reactions that interfere with establishment of pathogens in the gastrointestinal tract. The mechanisms of action are believed to involve competitive exclusion and production of inhibitory substances, including bacteriocins. These characteristics, as well as demonstrated adherence abilities in vitro, led to selection of certain Lactobacillus strains for clinical studies of cystitis. Weekly intravaginal Lactobacillus therapy reduced the recurrence rate of uncomplicated lower urinary tract infections in women. Use of Lactobacillus strains resistant to Nonoxynol-9, a spermicide that kills members of the protective normal vaginal flora, may have potential for use in women with recurrent cystitis using this contraceptive agent. In veterinary studies, bacterial interference by administration of probiotics has also been beneficial in disease prevention in animals. Carefully selected bacterial mixtures integrate with the gastrointestinal flora of the animals and can confer disease resistance and improve physiological function. Additional human and animal trials are needed to determine the practical, long-term usefulness of bacterial interference as a protective mechanism against infectious diseases.