Ingestion of Yogurt Containing Lactobacillus acidophilus as Prophylaxis for Candidal Vaginitis

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Ingestion of Yogurt Containing Lactobacillus acidophilus as Prophylaxis for Candidal Vaginitis

- Objective: To assess whether daily ingestion of yogurt containing Lactobacillus acidophilus prevents vulvovaginal candidal infections.

- Design: Crossover trial for at least 1 year during which patients were examined for candidal Infections and colonizations while receiving either a yogurt-free or a yogurt-containing diet. Patients served as their own controls.

- Setting: Ambulatory Infectious disease center in a teaching hospital providing tertiary care.

- Patients: Thirty-three women with recurrent candidal vaginitis were eligible after recruitment from community practices and clinics and through advertising. Twelve patients were eliminated for protocol violations. Of the remaining 21 patients, 8 who were assigned to the yogurt arm initially refused to enter the control phase 6 months later. Thus, 13 patients completed the protocol.

- Interventions: Women ate yogurt for 6 months of the study period.

- Measurements: Colonization of lactobacilli and candida in the vagina and rectum; candidal infections of the vagina.

- Main results: Thirty-three eligible patients were studied. A threefold decrease in Infections was seen when patients consumed yogurt containing Lactobacillus acidophilus. The mean (ñ SD) number of Infections par 6 months was 2.54 ñ 1.66 in the control arm and 0.38 ñ 0.51 per 6 months In the yogurt arm (P = 0.001). Candidal colonization decreased from a mean of 3.23 ñ 2.17 per 6 months in the control arm to 0.84 ñ 0.90 per 6 months in tho yogurt arm (P = 0.001).

- Conclusion: Daily ingestion of 8 ounces of yogurt containing Lactobacillus acidophilus decreased both candidal colonization and infection.

Candidal vaginitis is a common cause of gynecologic infections in the United States, with an increased incidence seen in pregnant women, diabetic women, and women receiving antibiotic or corticosteroid therapy. However, some women do not have these risk factors but experience chronic vulvovaginal candidal infections. The current therapies are often inadequate and many patients fail treatment; however, reports on systemic prophylaxis have been promising. Success with folk remedies, such as topical and systemic yogurt administration, has been reported anecdotally. No controlled studies have been done to evaluate yogurt as therapy or prophylaxis for this condition. We did a study to evaluate whether the regular ingestion of yogurt containing lactobacillus acidophilus would decrease the number of episodes of vaginal candidiasis.

Women who experience recurrent candidal vulvovaginitis can choose from myriad topical and systemic therapies, none of which appears to be "the answer." Vaginal instillation of yogurt and L. acidophilus-containing milk products have been tried in an uncontrolled fashion with varying degrees of purported success. We studied the use of ingested yogurt containing viable L acidophilus cultures as preventive therapy for candidal vaginitis.

In our study, we found a decrease in the incidence of candidal vulvovaginitis during the yogurt arm. An understanding of the pathogenesis of chronic candidal vaginal infections may help explain the ability of yogurt to decrease the occurrence of such infections. However, the reasons for persistent infection are unclear.

Persistent candidal colonization may play a role in the association between a gastrointestinal candidal reservoir with vaginal colonization, infection, and reinfection, but this is controversial. Identical Candida strains in the mouth, anus, and vagina, suggestive of auto-inoculation, have been demonstrated in some studies. Other studies have shown that gastrointestinal colonization has little to do with vaginal recurrences, either because the vaginal microflora are not directly linked to changes in the gastrointestinal microflora or because a vaginal reservoir exists that is responsible for reinfection. Recurrence has also been attributed to host factors or interactions of candida with other possible pathogens.

We evaluated the effect of the ingestion of yogurt containing L. acidophilus on gastrointestinal Lactobacillus colonization. Because there is evidence that lactobacilli can inhibit the growth of Candida, we attempted to assess the effect of colonization on gastrointestinal and vaginal candidal load or pathogenicity, or both.

Despite conflicting data about the ability of diet and L. acidophilus supplementation to alter the gastrointestinal microbiota, we anticipated an increase in L. acidophilus colony counts in stool and vaginal specimens after yogurt ingestion and a subsequent decrease in vaginal yeast colony counts. We chose a yogurt that had a high L. acidophilus content, because the evidence suggested that L. acidophilus had improved survival on passage through the acidic gastric pH when compared with other Lactobacillus species. Although Lactobacillus colonization increased when patients were on the yogurt arm, the difference was not significant. An association between the presence of Lactobacillus species in the rectum and vagina was seen, and yogurt ingestion had a marked effect on the incidence of candida infection in the vagina and rectum.

Certain lactobacilli may serve a function in the normal vaginal ecosystem. Eschenbach and colleagues reported that hydrogen peroxide-producing lactobacilli were inhabitants of the normal vagina, whereas anaerobic or non-H2O2 producers were associated with vaginosis. In our study, L. acidophilus strains in yogurt were found to produce hydrogen peroxide. Additionally, anaerobic lactobacilli predominated in the infected women and in the women on the non-yogurt arm.

The attrition rate in our study was high because participation involved some inconvenience to the patient. The degree of systematic attrition was unexpected, however, and was due to the refusal of patients who had experienced relief with yogurt to enter the control arm. This may have introduced bias. However, analysis of these women showed a rapid decrease in infections while on yogurt as compared with patients who began the study on the control arm. In addition, given the chronic nature and prolonged history of vaginitis in these women, this alteration of the study design should not have had any effect on the outcome.

Neither the patients nor the interviewer were blinded to the patient's treatment assignment, again introducing a potential bias. This was not seen as a major problem for two reasons: the magnitude of the effect of yogurt was quite large, more than could be reasonably attributed to bias; and the laboratory results were reported by personnel who had no knowledge of the patients' study arm. To further exclude the effect of observer bias, we analyzed candidal colonization exclusive of clinical findings and found a significant effect with a marked decrease in candidal growth when the patients were eating yogurt. A comparative, double-blinded study in which yogurt with live lactobacillus cultures is compared with irradiated or pasteurized yogurt would be desirable.

It appears that the gastrointestinal strain of L. acidophilus colonized the vaginal tract of our patients. Those interested in using dairy products to recolonize their gastrointestinal tracts should be wary of claims of dairy product manufacturers. When various brands of yogurt were tested, some did not contain the advertised lactobacilli.

All of the women enrolled carried a diagnosis of chronic candidal vaginitis, yet candidal infections were documented in only 41%. Some of the misdiagnoses included treatable problems (gonorrhea, bacterial vaginosis and Trichomonas infection), emphasizing the importance of making a specific etiologic diagnosis in patients with chronic vaginitis.

In summary, our prospective study of women with recurrent candidal vulvovaginitis found that the daily ingestion of 8 ounces of yogurt containing L. acidophilus decreased both candidal colonization and infection. The mechanism of action may be multifactorial; lactobacilli or a particular Lactobacillus species may have a direct effect on candidal growth and survival.

Townsend Letter for Doctors & Patients.

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By Eileen Hilton; Henry D. Isenberg; Phyllis Alperstein; Kenneth France and Michael T. Borenstein

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