The American Thoracic Society recently published a clinical practice guideline on diagnosing fungal infections in pulmonary and critical care medicine.
The guideline focuses on the use of common laboratory tests to diagnose invasive pulmonary aspergillosis, invasive candidiasis, and the three most common endemic mycoses: blastomycosis, coccidioidomycosis, and histoplasmosis. It was produced by an expert panel and was based on a systematic review of studies published from 1980 to April 2016. The guideline was published in the Sept. 1 American Journal of Respiratory and Critical Care Medicine.
Diagnostic methods for fungal infections include antigen testing in urine, blood, and bronchoalveolar lavage (BAL) fluid; serological testing to detect antibodies to fungal components; and nucleic acid-based assays using polymerase chain reaction (PCR). Specific recommendations include the following:
- Use serum galactomannan (GM) testing in severely immunocompromised patients with suspected invasive pulmonary aspergillosis, such as those with neutropenia or hematological malignancy or recipients of hematological stem-cell or solid-organ transplants who present with unexplained lung infiltrates (strong recommendation, high-quality evidence).
- Use BAL testing with GM in patients with suspected invasive fungal diseases, including those with a negative serum GM but strong risk factors for invasive aspergillosis or those with a positive serum GM but confounding factors for false-positive GM results (strong recommendation, high-quality evidence).
- Use blood or serum Aspergillus PCR testing in severely immunocompromised patients, such as those with hematological malignancy or recipients of hematological stem-cell or solid organ transplants, with suspected invasive pulmonary aspergillosis (strong recommendation, high-quality evidence).
- Include Aspergillus PCR on BAL testing as part of the evaluation of severely immunocompromised patients with suspected invasive pulmonary aspergillosis (strong recommendation, high-quality evidence).
- Do not rely solely on results of serum β-D-glucan testing alone for diagnostic decision making in critically ill patients for whom there is clinical concern for invasive candidiasis (conditional recommendation, low-quality evidence).
- Use more than one diagnostic test, including direct visualization and culture of sputum BAL or other biopsy material, urine antigen testing, and serum antibody testing, in patients with appropriate geographic exposure and illness compatible with infection or pneumonia due to blastomycosis or coccidioidomycosis. The current evidence does not support a single best test as being sensitive enough to be ordered in isolation from other testing. Tailor the approach based on severity of illness, clinical context, and availability of tests (conditional recommendation, moderate-quality evidence).
- Use urinary antigen testing for blastomycosis together with clinical and epidemiological data to establish the diagnosis in patients with suspected blastomycosis, particularly immunocompromised patients (conditional recommendation, moderate-quality evidence).
- Perform urinary and serum antigen testing to aid in establishing the diagnosis in patients with suspected coccidioidomycosis, particularly immunocompromised patients (conditional recommendation, moderate-quality evidence).
- Use Histoplasma antigen in urine or serum for rapid diagnosis of suspected disseminated and acute pulmonary histoplasmosis when timely diagnosis and treatment are of paramount importance to patient outcomes (strong recommendation, high-quality evidence).