Factors that predispose to overgrowth of bacterial vaginal pathogens include Use of antibiotics (which may decrease lactobacilli) Alkaline vaginal pH due to menstrual blood or semen Vaginal douching Pregnancy Diabetes mellitus An intravaginal foreign body (eg, a forgotten tampon or vaginal pessary) Etiology of Vaginal Itching and Discharge The most common causes of vaginal itching and discharge vary by patient age (see table Some Causes of Vaginal Pruritus and Discharge).