Fungus (Mycology) Culture w/ Reflex*

Isolate and identify fungi. Blood: establish the diagnosis of fungal infections including fungemia, fungal endocarditis, and disseminated mycosis in patients at risk for fungal infections.

Blood: A single (or even multiple) negative fungal blood culture does not exclude disseminated fungal infection. If disseminated or deep fungal infection is strongly suspected despite repeatedly negative blood cultures, biopsy of the appropriate tissue and/or bone marrow aspiration for sections and fungus culture should be considered.

Stool: Use of this test is generally limited to detection of Candida. Stool cultures have a low yield and are not recommended for the isolation of systemic fungi; however, Histoplasma capsulatum is recovered from the stool of AIDS patients with disseminated infection.

Blood: Fungemia can be a complication of venous or arterial catheterization, hyperalimentation, the acquired immunodeficiency syndrome (AIDS), and therapy with steroids, antineoplastic drugs, radiation, or broad spectrum antimicrobial agents. Intravenous drug abusers are prone to Candida endocarditis. Although many fungal species, including Histoplasma capsulatum, Coccidioides immitis, and Cryptococcus neoformans are recoverable from blood cultures, the most common cause of fungemia is Candida albicans followed by other Candida sp, including Candida glabrata. Fungemia represents a failure of the host defense system. Fungemia may be precipitated by contamination of an indwelling catheter or, in the critically ill and immunocompromised patient, contamination of the gastrointestinal and less frequently the urinary tract.¹ In a review of 356 patients with neoplastic disease, Candida sp was recovered in 7% of neutropenic patients.

In the potentially immunocompromised host, a temperature of 38.5°C (101°F) for more than two hours, which is not associated with the administration of a pyrogenic drug (chemotherapy), indicates the presence of infection until proven otherwise. In these patients, characteristic signs and symptoms are frequently absent. A careful physical examination, including mouth, anus, and genitalia, may reveal the site of infection. Therapy must be instituted as soon as appropriate specimens are collected. Most infections in these patients are caused by gram-negative organisms (eg, E coli, Pseudomonas sp, Klebsiella sp) and by S aureus; however, fungi and other usually nonpathogenic organisms must be considered significant.²

Rarely, blastospores (budding yeast structures) and pseudohyphae can be seen by examination of Wright-stained venous peripheral blood smears. This technique may allow early diagnosis and therapy before culture results are available.³

Eye: The more common causes of keratomycosis include Fusarium solani, Candida albicans, Aspergillus fumigatus, Curvularia sp, Aspergillus flavus, other species of Aspergillus, Penicillium, Paecilomyces, Fusarium, and many other species.⁴ A keratomycosis-like clinical presentation may also be encountered caused by Nocardia asteroides and Mycobacterium fortuitum. Keratomycosis is a rare complication of contact lens use.⁵

Sinus: Fungal sinusitis has been increasingly recognized in otherwise healthy teenagers who often present with a history of recurrent sinusitis, asthma, and/or polyps. At surgery, material is consistently described as thick peanut butter-like or pistachio pudding-like. Dematiaceous fungi are the most common cause.

Skin: Candida sp may colonize skin. Clinical diagnosis of Candida infection involves consideration of predisposing factors such as occlusion, maceration altered cutaneous barrier function. Signs of Candida infection include bright erythema, fragile papulopustules, and satellite lesions.⁶ Patients with defects in T-lymphocyte responses, such as AIDS patients or individuals being treated with antineoplastic drugs, are especially susceptible to many fungal infections including superficial mycoses.^7,8