Mold-Associated Infections

Mold infections range in spectrum from colonization to hypersensitivity reactions. In addition, opportunistic molds have become increasingly recognized as a cause of life-threatening invasive infection in severely ill or immunocompromised patients.

Diagnosis

Diagnosis of Mold-Associated Syndromes

Differential Diagnosis

Monitoring

  • Galactomannan antigen
    • May be used to monitor immunocompromised patients who are experiencing neutropenia
      • Limited sensitivity in nonneutropenic patients
    • Requires a moderate prevalence of invasive aspergillosis in the community; not as useful for monitoring if prevalence is low
  •  (1,3)-β-D-glucan (Fungitell)
    • May be used to monitor immunocompromised patients who are experiencing neutropenia; most experience is with monitoring for invasive aspergillosis and candidiasis
    • Test has high negative predictive value; false negatives uncommon

Background

Epidemiology

Invasive fungal disease occurs most commonly in immunocompromised patients

Etiology

  • Molds most often associated with significant disease include
    • Hyaline molds (three most common)
      • Aspergillus fumigatus (A)
      • Fusarium spp (F)
      • Scedosporium spp (S)
    • Zygomycetes
      • Hallmarks of Zygomycetes infection are vascular invasion and tissue necrosis (presence of black tissue)
    • Dematiaceous fungi
      • Includes a large group of darkly pigmented organisms

Risk Factors

Mold-Associated Symptoms – Pulmonary

Mold-Associated Symptoms – Nonpulmonary

ARUP Lab Tests

Test for Aspergillus as cause of pulmonary disease

A negative test may not rule out clinical allergy or even anaphylaxis

For the direct detection and identification of fungi in tissue

Adjunct test for the diagnosis of invasive mucormycosis caused by the most common Mucorales genera. Does not replace culture and histopathology.

Detect Aspergillus species and differentiate Aspergillus fumigatus

Aid in the diagnosis of invasive/disseminated aspergillosis

Negative results do not rule out invasive aspergillosis

Many agents may cross-react with test (food, antibiotics, etc)

Recommend serial sampling for high-risk patients if suspicion is high

Single positive test result (index ≥0.5) should be confirmed by separate serum specimen

Aid in the diagnosis of pulmonary aspergillosis

Gold standard test to diagnose fungi as agent of infection

Identify fungus using fungal smear (eg, yeast, aseptate hyphae, septate hyphae)

Identify fungi from culture

Testing to differentiate between Candida albicans and C. dubliniensis performed by request only 

Gold standard test to diagnosis fungi as agent of infection in blood

Aid in the diagnosis of invasive/disseminated fungal infections (eg, Pneumocystis jirovecii, Aspergillus, or Candida)

Does not detect fungal species that produce very low levels of (1,3)-β-D-glucan (eg, Cryptococcus)

Does not detect Zygomycetes spp, which are not known to produce (1,3)-β-D-glucan (eg, AbsidiaMucorRhizopus)

In addition, the yeast phase of Blastomyces dermatitidis may not be detected by the assay

Aid in diagnosing allergic bronchopulmonary aspergillosis (ABPA)

Not appropriate for diagnosing invasive aspergillosis

Determine in vitro susceptibility to antifungal agents for fungal organisms

Agents tested include amphotericin B, anidulafungin, caspofungin, fluconazole, 5-fluorocytosine, itraconazole, micafungin, posaconazole, and voriconazole

Selective reporting by organism

Related Tests

Not recommended for the diagnosis of invasive aspergillosis

Consider ordering an aspergillus galactomannan antigen test (serum or bronchoscopy)

Negative fungal serology does not rule out the possibility of current infection

Not recommended for the diagnosis of invasive aspergillosis

Consider ordering an aspergillus galactomannan antigen test (serum or bronchoscopy) 

For suspicion of coccidioidal meningitis, refer to coccidioides antibodies panel for cerebrospinal fluid (CSF)

Not recommended for the diagnosis of fungal infection of the central nervous system

Refer to individual fugal antibody tests, as relevant to patient exposure(s)

Not recommended

Refer to individual fugal antibody tests, as relevant to patient exposure(s)

Limited clinical utility

Best evidence for infection is significant change on 2 appropriately timed specimens where both tests are done in the same laboratory at the same time; however, low levels of IgM may occasionally persist for >12 months

Identify fungi from culture

Medical Experts

Contributor

Couturier

Marc Roger Couturier, PhD, D(ABMM)
Associate Professor of Clinical Pathology, University of Utah
Medical Director, Parasitology/Fecal Testing, Infectious Disease Antigen Testing, Bacteriology, and Molecular Amplified Detection, ARUP Laboratories
Contributor

Slev

Patricia R. Slev, PhD
Associate Professor of Clinical Pathology, University of Utah
Section Chief, Immunology; Medical Director, Immunology Core Laboratory, ARUP Laboratories

References

Additional Resources
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  • Resources from the ARUP Institute for Clinical and Experimental Pathology®