Methods and materials for treating bacterial vaginosis (“BV”) are provided. Cervicovaginal secretions (“CVS”) from a woman with vaginal microbiota dominated (>50%) by one of the species of lactobacillus typically found in the human vagina, e.g. Lactobacillus crispatus, L. iners, L. gasseri, L jensenii, is transplanted to women with BV as a method for restoring beneficial vaginal microbial communities and/or increasing resistance to sexually transmitted disease. Efficacy can be enhanced, or the properties of the endogenous CVS improved, through administration of an acidifying agent such as lactic acid. The examples demonstrate the role of healthy CVS in disease resistance, and the effect of pH on CVS properties. The examples also describe the collection and transplantation of healthy beneficial CVS into women at risk for, or after treatment for, BV.