Specific probiotic strains are effective for genitourinary infections

Townsend Letter for Doctors and Patients, Nov, 2006 by Alan R. Gaby

Various strains of "friendly" bacteria (typically referred to as probiotics) have been found to accelerate recovery from certain types of infections and to help prevent recurrences. Probiotics are used to prevent urinary tract infections (UTIs), vaginal infections, Clostridium difficile diarrhea, traveler's diarrhea, and antibiotic-induced diarrhea. Taking probiotics may also improve the effectiveness of conventional therapy for eradicating Helicobacter pylori infections.

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The normal bacterial flora differs substantially in different parts of the body. Probiotic strains may also differ, therefore, in their capacity to colonize--and provide protection to--different areas of the body. For example, an organism that is effective in the gastrointestinal tract might be less effective against genitourinary infections, and vice versa.

Research performed over the past two decades suggests that two particular strains of lactobacillus--Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 (formerly known as L. fermentum RC-14)--are especially beneficial for preventing and treating genitourinary infections in women. When administered intravaginally to healthy women, these organisms were more effective than other strains of lactobacilli (such as L. rhamnosus GG) at colonizing the vaginal mucosa. (1) In addition, L. rhamnosus GR-1 and L. reuteri RC-14 were found to be preferable to other probiotic strains with respect to certain predictors of urogenital health (e.g., adhesion to uroepithelial cells, competitive exclusion of pathogens, and production of inhibitors of the growth of pathogenic organisms, including Candida albicans). (2,3)

In case reports and uncontrolled trials, intravaginal administration of one or both of these probiotic agents reduced the recurrence rate of UTIs in women who had a history of UTIs. This treatment also appeared to be effective for preventing vaginal yeast infections. Fifty women who received weekly vaginal applications of L. rhamnosus GR-1 and L. reuteri RC-14 for up to one year experienced no cases of yeast vaginitis; according to the investigators, 200 episodes of yeast infections would have been expected in this number of women. (4)

L. rhamnosus GR-1 and L. reuteri RC-14 have also been shown to be effective when taken orally. After oral administration, these organisms survive passage through the gastrointestinal tract and apparently migrate to and colonize the vaginal mucosa. In a study of ten women with recurrent genitourinary infections who received L. rhamnosus GR-1 and L. reuteri RC-14 ([10.sup.9] organisms of each strain per dose) twice a day for 14 days, both organisms could be recovered from the vagina in all ten patients. In some cases, the organisms persisted in the vagina at least ten weeks after the treatment was discontinued. In addition, this treatment normalized the vaginal flora in women with bacterial vaginosis. (5) In a study of women with no history of urogenital infections in the previous 12 months, oral administration of L. rhamnosus GR-1 and L. reuteri RC-14 for 60 days decreased vaginal concentrations of yeast and potentially pathogenic bacteria. (6)

In a recent double-blind trial, these organisms were found to be beneficial in the treatment of bacterial vaginosis, a common and often difficult-to-treat vaginal infection. One-hundred-twenty-five Nigerian women with bacterial vaginosis were given oral metronidazole (500 mg twice a day for seven days). They were also randomly assigned to receive, in double-blind fashion, one capsule twice of day of a combination of L. rhamnosus GR-1 and L. reuteri RC-14 or placebo for 30 days, beginning with the start of metronidazole therapy. Each capsules contained [10.sup.9] viable cells of each strain. The probiotics were taken at least one hour after the antibiotic, although the two strains are said to be resistant to metronidazole. Cure of bacterial vaginosis was defined as a normal Nugent score, a negative sialidase test, and no symptoms or signs of bacterial vaginosis at day 30. Among the 106 patients who completed the study, the cure rate was 88% in the probiotic group and 40% in the placebo group (p<0.001). The proportion of patients who still had bacterial vaginosis at day 30 was 0% in the probiotic group and 30% in the placebo group, while the remaining patients in the two groups fell into the intermediate category based on the Nugent score, sialidase results, and clinical findings. (7)

These studies suggest that L. rhamnosus GR-1 and L. reuteri RC-14 may be ideal probiotic strains for the prevention and treatment of recurrent UTIs, vaginal candidiasis, and bacterial vaginosis. It should be noted that one of the researchers involved in most of the studies holds the patent on these organisms. Independent confirmation of this work would therefore be welcomed. The combination of L. rhamnosus GR-1 and L. reuteri RC-14 is available under the name Fem-Dophilus (Jarrow Formulas, Los Angeles, California).

Alan R. Gaby, MD

Notes

1. Gardiner GE, et al. Persistence of Lactobacillus fermentum RC-14 and Lactobacillus rhamnosus GR-1 but not L. rhamnosus GG in the human vagina as demonstrated by randomly amplified polymorphic DNA. Clin Diagn Lab Immunol. 2002;9:92-96.

2. Reid G, Bruce AW. Selection of lactobacillus strains for urogenital probiotic applications. J Infect Dis. 2001;183(Suppl 1):S77-S80.