Key Clinical Questions
When should a positive urine culture for Candida species be treated?
When should invasive candidiasis be suspected? How is it diagnosed and treated?
What is the clinical significance of a positive sputum culture for Aspergillus species?
How useful are antigen detection tests for the diagnosis of infection with Candida and Aspergillus species?
When should infectious diseases be consulted?
Candida species are normal commensal flora of the oropharynx, bowel, vagina, and skin. Candida overgrowth of these surfaces may arise in the setting of broad-spectrum antibiotics, corticosteroid exposure, diabetes mellitus, or HIV infection, resulting in oral thrush, Candida esophagitis, intertriginous candidiasis, and vaginal candidiasis. High estrogen states, such as pregnancy or oral contraceptive use, are an additional risk factor for vaginal yeast infection. Localized Candida skin infections (Candida intertrigo) are often seen in moist, macerated intertriginous folds, such as in the groin, perineum (diaper rash), pannus, axillae, and breasts.
While superficial candidiasis is common in both ambulatory and hospitalized patients, candidemia and disseminated candidiasis are usually seen in health care settings. Candidemia is the third most common bloodstream infection in hospitalized patients, and is associated with high mortality rates. Risk factors include critical illness, broad-spectrum antibiotic or corticosteroid exposure, intra-abdominal surgery, hemodialysis, central venous catheters, parenteral nutrition, intravenous drug use, and neutropenia.
MUCOCUTANEOUS CANDIDA (CUTANEOUS, THRUSH, ESOPHAGITIS, VAGINITIS)
The diagnosis of mucocutaneous Candida infections is usually made clinically. Cutaneous candidiasis has a typical distribution in intertriginous areas, with central erythema and maceration, surrounded by a collar of scale (Figure 201-1). Beyond this, there may be papular and pustular satellite lesions. Disseminated, hematogenous candidiasis can lead to a different, diffuse maculopapular rash (Figure 201-2).
Candida intertrigo, with prominent satellite lesions at the margins. (Reproduced, with permission, from Wolff K, Goldsmith LA, Katz SI, et al. Fitzpatrick’s Dermatology in General Medicine, 7th ed. New York, NY: McGraw-Hill; 2008. Fig. 189-4B.)
Skin manifestations of disseminated fungal infections in neutropenic patients with leukemia: Candida tropicalis fungemia with skin dissemination (left) and cutaneous invasive aspergillosis mimicking bacterial cellulitis (right).
Oral thrush presents with painless white plaques on the tongue and, sometimes, the hard palate and the oropharynx (Figure 201-3), that are easily scraped off. Fissures of the angles of the mouth (cheilitis) may also be present. Budding yeasts, hyphae, and pseudohyphae of Candida can be seen on microscopy when scrapings of skin or oral lesions are mixed with a drop of 10% potassium hydroxide, which digests host cells but not fungi.
Oral thrush, with characteristic plaques on the hard palate. (Reproduced, with permission, ...