Candidiasis

Candidiasis is a fungal infection caused by opportunistic species of Candida. It can affect various anatomical sites, including the skin, oral cavity, nails, and genitourinary tract. Among its forms, vaginal candidiasis is the most common type of mucosal infection. It typically results from the overgrowth of Candida albicans in the vaginal mucosa. Under normal conditions, C. albicans exists as a commensal organism within the vaginal microbiota, regulated by the dominance of lactobacilli, which produce lactic acid and help maintain a slightly acidic vaginal pH.

Disruption of Vaginal Microbiota

When this microbial balance is disturbed—by factors such as immunosuppression, antibiotic use, hormonal contraceptives, or a decline in lactobacilli numbers—Candida albicans can shift from a benign yeast form to a pathogenic hyphal form. This morphological change is associated with altered vaginal conditions, including increased pH.

Mechanisms of Pathogenicity

The hyphal form of C. albicans is particularly virulent. It secretes hydrolytic enzymes, including aspartyl proteases and phospholipases, which degrade epithelial barriers and immune proteins. These enzymes facilitate tissue penetration and help the fungus evade the immune system. In addition, C. albicans forms biofilms—structured microbial communities embedded in an extracellular matrix—that resist antifungal treatments and limit immune cell access.

Immune Response and Clinical Presentation

The immune system responds with an inflammatory cascade involving neutrophils and macrophages. While these cells work to control the infection, their activity can worsen inflammation and contribute to symptoms. Vaginal candidiasis commonly presents with erythema, edema, itching, a burning sensation, and thick white discharge. Recurrent cases may involve non-albicans species or suggest underlying immune or microbial imbalances that require further evaluation.