Fungal infections have assumed an increasingly important role as use of broad-spectrum antimicrobial agents has increased and the number of immunodeficient patients has grown. Some pathogens (eg, Cryptococcus, Candida, Pneumocystis, Fusarium) rarely cause serious disease in immunocompetent hosts. Other endemic fungi (eg, Histoplasma, Coccidioides, Paracoccidioides) commonly cause disease in immunocompetent persons but tend to be more aggressive in immunocompromised ones. Superficial mycoses are discussed in Chapter 6. Successful management of most systemic fungal infections requires knowledge of the natural history of these diseases and the specific tests needed to make a diagnosis as well as familiarity with the unique pharmacokinetics, adverse effects, and drug interactions of the various therapeutic agents. Consequently, clinicians with extensive experience in the management of these disorders should be routinely consulted.
ESSENTIALS OF DIAGNOSIS
Common normal flora but opportunistic pathogen.
Mucosal disease, particularly vaginitis and esophagitis.
Risk factors for fungemia: neutropenia, intravenous catheter, abdominal surgery, total parenteral nutrition, kidney disease, broad-spectrum antibiotics.
Candida albicans can be cultured from the mouth, vagina, and feces of most people. Cutaneous and oral lesions are discussed in Chapters 6 and 8, respectively. The risk factors for invasive candidiasis include prolonged neutropenia, recent abdominal surgery, broad-spectrum antibiotic therapy, kidney disease, and the presence of intravascular catheters (especially when providing total parenteral nutrition). Cellular immunodeficiency predisposes to mucocutaneous disease. When no other underlying cause is found, persistent oral or vaginal candidiasis should arouse a suspicion of HIV infection.
Esophageal involvement is the most frequent type of significant mucosal disease. Presenting symptoms include substernal odynophagia, gastroesophageal reflux, or nausea without substernal pain. Oral candidiasis, though often associated, is not invariably present. Diagnosis is best confirmed by endoscopy with biopsy and culture.
Vulvovaginal candidiasis occurs in an estimated 75% of women during their lifetime. Risk factors include pregnancy, uncontrolled diabetes mellitus, broad-spectrum antimicrobial treatment, corticosteroid use, and HIV infection. Symptoms include acute vulvar pruritus, burning vaginal discharge, and dyspareunia.
Most cases of candidal funguria are asymptomatic and represent specimen contamination or bladder colonization. However, symptoms and signs of true Candida urinary tract infections are indistinguishable from bacterial urinary tract infections and can include urgency, hesitancy, fever, chills, or flank pain.
Invasive candidiasis can be (1) candidemia without deep-seated infection; (2) candidemia with deep-seated infection (typically eyes, kidney, or abdomen); and (3) deep-seated candidiasis in the absence of bloodstream infection. Varying ratios of these clinical entities depends on the predominating risk factors for affecting patients (ie, neutropenia, dialysis, postsurgical). The clinical presentation of candidemia varies from minimal fever to septic shock that can resemble a severe bacterial infection. The diagnosis of invasive Candida infection is problematic because ...