David J. Chase

Glycerol Monolaurate Inhibits Candida and Gardnerella vaginalis In Vitro and In Vivo but Not Lactobacillus

ABSTRACT We investigated the effects of glycerol monolaurate (GML) on Lactobacillus, Candida, and Gardnerella vaginalis human vaginal microflora. Our previous work demonstrated that 6 months of GML treatment vaginally does not alter lactobacillus counts in monkeys. Candida and G. vaginalis are commonly associated with vaginal infections in women, many becoming chronic or recurrent. In vitro growth inhibition studies determined the effects of GML (0 to 500 μg/ml) against multiple Candida species and G. vaginalis. A randomized, double-blind study investigated the effects of GML on vaginal microflora Lactobacillus, Candida, and G. vaginalis in colonized or infected women (n = 36). Women self-administered intravaginal gels containing 0% (n = 14), 0.5% (n = 13), or 5% (n = 9) GML every 12 h for 2 days. Vaginal swabs were collected before and immediately after the first gel administration and 12 h after the final gel administration. Swabs were tested for Lactobacillus, Candida, G. vaginalis, and GML. In vitro GML concentrations of 500 μg/ml were candicidal for all species tested, while a concentration of 10 μg/ml was bactericidal for G. vaginalis. Control and GML gels applied vaginally in women did not alter vaginal pH or Lactobacillus counts. Control gels reduced G. vaginalis counts but not Candida counts, whereas GML gels reduced both Candida and G. vaginalis. No adverse events were reported by participating women. GML is antimicrobial for Candida and G. vaginalis in vitro. Vaginal GML gels in women do not affect Lactobacillus negatively but significantly reduce Candida and G. vaginalis.

Reduction in Staphylococcus aureus Growth and Exotoxin Production and in Vaginal Interleukin 8 Levels Due to Glycerol Monolaurate in Tampons

BACKGROUND Staphylococcal menstrual toxic shock syndrome depends on vaginal production of exotoxins. Glycerol monolaurate (GML) inhibits Staphylococcus aureus exotoxin production in vitro. The purpose of this study was to determine whether GML, as a tampon fiber finish, inhibits production of exotoxins and the cytokine interleukin 8 (IL-8) during normal tampon use. METHODS On day 2 of menstruation, when vaginal S. aureus counts are high in colonized women, study participants exchanged their own preferred tampons, after wearing them for 2-6 h, for study tampons with or without GML (assigned randomly and blindly), which they then wore for 4-6 h. The womens own tampons and the study tampons with or without GML were assayed for S. aureus, the exotoxins toxic shock syndrome toxin 1 and alpha-toxin, and IL-8. RESULTS A total of 225 women completed the study. S. aureus was present in the tampons of 41 women (18%). Lower numbers of S. aureus and the exotoxins were detected in study tampons with or without GML than in womens own tampons; lower amounts of the exotoxins were present in study tampons with GML than study tampons without GML. The IL-8 level was lower in tampons from women without vaginal S. aureus compared with women with S. aureus and was lower in study tampons with GML than in study tampons without GML. CONCLUSIONS Tampons that contain GML reduce S. aureus exotoxin production. S. aureus increases vaginal IL-8 levels, and GML reduces production of this proinflammatory cytokine. These results suggest that GML added to tampons provides additional safety relative to menstrual toxic shock syndrome as well as benefits for vaginal health generally, thus supporting the addition of GML to tampons.