Candidiasis

Abstract

Candida species are yeast normally present as commensals in the human gastrointestinal and genitourinary tract. Depending on the immune status of the host, Candida species infections can cause a wide spectrum of diseases ranging from local infections to disseminated disease. Local infections in an immunocompetent host typically involve the skin and mucus membranes. Invasive candidiasis can occur in immunocompromised patients, disseminating hematogenously to other sites causing multiorgan involvement.

Candida albicans is the most common species to cause infection in humans; however, invasive infections caused by Candida species other than albicans are being reported with increasing frequency. The observation is important because several of the emerging non-albicans are resistant to commonly used antifungal medications, and some have proven to be highly virulent. Medically important non-albicans Candida species include C. parapsilosis, C. glabrata, C. krusei, C. lusitaniae, C. tropicalis, and C. auris.

Risk factors for the development of candidiasis include the use of broad-spectrum antibiotics, use of oral or inhaled glucocorticoids, treatment with chemotherapy or radiation therapy for underlying malignancy, diabetes mellitus, neutropenia, and primary or acquired defects in cell-mediated immunity. Neonates, especially those born prematurely and those born with a birth weight of less than 1500 g, are also at high risk for developing candidiasis.

Localized candida infections include oropharyngeal candidiasis (thrush), yeast diaper dermatitis, vulvovaginitis, and balanitis. Invasive candidiasis is a major contributor of morbidity and mortality in hospitalized patients and is currently the second most common cause of central catheter-associated bloodstream infections in the United States. Invasive candidiasis is a leading cause of mortality among patients with cancer and recipients of solid-organ or hematopoietic stem cell transplants.

The diagnosis of candidiasis is based on both clinical and laboratory data. Localized candida infections are most often diagnosed clinically, but when the provider is in doubt, an unstained wet preparation or Gram stain can be performed on a scraping from the lesion. Candida will appear as Gram-positive budding yeasts. Invasive candidiasis is diagnosed using a combination of clinical findings, imaging modalities, blood cultures, tissue cultures, and antigen-based tests.

Several topical, oral, and parenteral antifungal medications are available for the treatment of candida infections. The location and severity of the infection, together with host factors, including the presence or absence of immunosuppression help to guide selection of the optimal antifungal medication and its preferred route of administration.