Toxic shock syndrome: an ecologic imbalance within the genital microflora of women?

Epidemiologic data suggested that toxic shock syndrome (TSS) may be caused by an imbalance among the flora of the female genital tract. Since natural defense mechanisms often involve antagonistic interactions between the flora and potential pathogens, the ability of genital lactobacilli to inhibit Staphylococcus aureus was determined in agar overlay assays. Lactobacilli were chosen for study because previous investigations had suggested an important role for this genus in maintenance of health of the female genital tract. Fourteen of 50 strains of lactobacilli and Lactinex inhibited the growth of certain staphylococci, including strains from cases of TSS. The inhibitory activity of some lactobacilli was variable and could be enhanced by exogenously supplied substrates. Growth of one consistently inhibitory lactobacillus was inhibited by Staphylococcus aureus. A model for the etiology of toxic shock syndrome in menstruating women is proposed. The model includes antagonistic interactions between lactobacilli and staphylococci and the influence of tampons on these interactions to favor the staphylococcus.