Common Causes of Vaginal Candidiasis in Reproductive-Age Women
Vaginal candidiasis is primarily caused by overgrowth of Candida albicans (responsible for approximately 90% of cases), with the infection developing when the normal balance between yeast colonization and the host vaginal environment is disrupted by physiological or behavioral factors. 1, 2
Primary Causative Organism
- Candida albicans accounts for the vast majority (approximately 90%) of vulvovaginal candidiasis cases 2, 3
- Non-albicans Candida species (particularly C. glabrata, C. krusei) are increasingly identified and tend to have reduced antifungal susceptibility and higher recurrence rates 2, 4
- Approximately 10-20% of reproductive-age women normally harbor Candida species in the vagina asymptomatically, so colonization alone does not equal infection 5
Host-Related Risk Factors
Hormonal and Metabolic Factors
- Pregnancy increases susceptibility to VVC and requires modified treatment (topical azoles only) 6, 2
- Uncontrolled diabetes creates a favorable environment for yeast overgrowth 2
- Hormone replacement therapy can predispose to infection 2
Medication-Related Factors
- Antibiotic use disrupts normal vaginal flora, particularly Lactobacillus species that normally suppress yeast overgrowth 2
- Glucocorticoid use impairs local immune defenses 2
- Immunosuppressive medications reduce host resistance to fungal overgrowth 2
Immune Status
- HIV infection with lower CD4+ T-cell counts is associated with increased rates of VVC, though treatment remains identical to HIV-negative women 1, 6
- Genetic predispositions may affect individual susceptibility 2
Behavioral and Environmental Risk Factors
- Oral contraceptive use alters the hormonal milieu favoring yeast proliferation 2
- Intrauterine device (IUD) use has been associated with increased VVC risk 2
- Spermicide and condom use may alter vaginal pH and microbiota 2
- Certain hygiene practices and tight-fitting clothing can create conditions favorable for yeast growth 2
- Sexual practices, though VVC is not considered a sexually transmitted infection and partner treatment is not routinely recommended 1, 6
Microbiological Mechanism
- Disruption of normal vaginal microbiota, particularly reduction in hydrogen peroxide-producing Lactobacillus species, allows Candida overgrowth 7, 4
- Yeast-to-hyphal transition of C. albicans occurs when environmental conditions favor pathogenicity over commensalism 7
- Vaginal pH remains normal (≤4.5) in VVC, distinguishing it from bacterial vaginosis or trichomoniasis which elevate pH above 4.5 6, 8
Clinical Caveat
The key distinction is between asymptomatic colonization and symptomatic infection - treatment should only be initiated when symptoms are present along with laboratory confirmation, as treating asymptomatic colonization is not recommended 6, 5. The most specific symptom is vaginal itching, and absence of itching should prompt consideration of alternative diagnoses 6, 8.