The In Vitro Effectiveness of Lactobacillus fermentum Against Different Candida Species Compared With Broadly Used Azoles.

Goals: To investigate the possible use of Lactobacillus strains in the prophylaxis and/or adjuvant therapy of acute vulvovaginal candidiasis and other vaginal infections sustained by Candida yeasts.

Background: The incidence of Candida infections has substantially increased in recent years. Treatment of vaginal infections with lactobacilli has a long tradition, starting with Döderlein's description of the vaginal microbiota.

Materials And Methods: We assessed the activity of serially diluted fluconazole and miconazole (from 3 ng/mL to 1 mg/mL) against Candida strains. Serial dilutions of the azoles were prepared in Sabouraud Dextrose Broth in the presence of Candida strains. Broths were incubated under aerobic condition at 30°C, and the optical density was measured at 560 nm. Minimum inhibitory concentration was defined as the lowest concentration of the antibiotic that completely inhibited visible growth.

Results: An evident resistance to the azoles used was recorded for all species of Candida, with the exception of Candida parapsilosis. For this species, a minimum inhibitory concentration ≤1 mg/mL was obtained, thus confirming the slight sensitivity to fluconazole and miconazole.All Lactobacillus strains tested, namely LF5, LF09, LF10, and LF11, have the ability to significantly inhibit the growth of the five species of Candida of at least 4 logarithms. Furthermore, the best result obtained with miconazole on C. parapsilosis is still 2 logarithms lower.

Conclusions: The use of beneficial bacteria, especially lactobacilli, could be regarded as a good alternative for the prevention and treatment of Candida infections.