A Vaginal Yeast Infection Is NOT a Bacterial Infection—It Is a Fungal Infection
Vaginal yeast infection (vulvovaginal candidiasis) is caused by Candida species—most commonly Candida albicans—which are fungi (yeasts), not bacteria. 1, 2
Understanding the Distinction
Candidiasis is a fungal infection caused by overgrowth of Candida yeast species in the vagina and vulva, with C. albicans accounting for approximately 52–88% of cases. 2, 3, 4
Bacterial vaginosis is a separate condition caused by replacement of normal Lactobacillus vaginal flora with anaerobic bacteria (Prevotella, Mobiluncus), Gardnerella vaginalis, and Mycoplasma hominis—this is the bacterial infection that can affect the vagina, but it is completely different from yeast infection. 1, 5
The three most common causes of vaginal discharge are distinct entities: trichomoniasis (caused by the protozoan parasite Trichomonas vaginalis), bacterial vaginosis (polymicrobial bacterial overgrowth), and candidiasis (fungal infection). 1, 6
Why the Confusion Exists
All three conditions present with vaginal discharge and can coexist simultaneously, but they require different treatments because they are caused by completely different types of microorganisms. 1, 6
Vaginal pH helps differentiate these infections: candidiasis maintains normal vaginal pH (≤4.5), whereas bacterial vaginosis and trichomoniasis elevate pH above 4.5. 1, 2, 6
Clinical Implications
Antifungal medications (azoles like clotrimazole, miconazole, fluconazole) treat yeast infections because they target fungal cell membranes, achieving >90% cure rates for uncomplicated candidiasis. 2
Antibacterial medications (metronidazole) treat bacterial vaginosis and trichomoniasis but do not treat yeast infections—in fact, antibiotic use is a recognized risk factor for developing vulvovaginal candidiasis by disrupting protective vaginal Lactobacillus bacteria. 2, 7
Approximately 75% of women experience at least one episode of vulvovaginal candidiasis during their lifetime, making it one of the most common fungal infections worldwide. 2, 4, 7
Common Pitfall to Avoid
- Never use antibiotics to treat a yeast infection—this will worsen the condition by further eliminating protective bacterial flora and allowing more fungal overgrowth. 7