Description:
These organisms, which invade the tissues of immune-compromised patients, are all saprophytes (saprobes). Therefore, when one of these molds is isolated in the laboratory, it is not always easy to determine if the isolate is a contaminant or an actual cause of disease. However, all isolates must be reported, and the clinician must determine the importance based on the patient's clinical picture. Patients most at risk include those with lymphoma, diabetes, leukemia, and transplant recipients.
Common Species:
Many species can be opportunists. Common isolates include members of Aspergillus spp., Fusarium spp., Geotrichum candidum, Penicillium spp., Acremonium spp., Paecilomyces spp. (some have been renamed), and Scopulariopsis spp.
Mention will be made of Scedosporium apiospermum and Scedosporium boydii (once considered the asexual form of Pseudallescheria boydii, all causative agents of pseudallescheriasis - the spread into the central nervous system from a pulmonary infection occurring in immunocompromised individuals), and Gliocladium, though they are very uncommon.
Epidemiology and Disease:
- Aspergillosis, infection with Aspergillus spp. can involve many types of disseminated infections in immune-compromised patients. Manifestations of the disease include sinusitis, bronchopulmonary aspergillosis, ear, nail, and sinus infections. Also, CNS and endocarditis can be caused by these species.
- Fusarium spp. infections are becoming more common. They are normally found in the environment but can cause skin infections, mycotic keratitis, disseminated fusariosis, and fungemia (not usually seen in aspergillosis). Other infections by Fusarium include sinusitis and wound infections. However, these species can sometimes be recovered from patients who show no signs of infection.
- Geotricum candidum is uncommon, but can occasionally cause wound infections and thrush.
- Penicillium spp. are very commonly recovered but rarely cause disseminated infections. They can cause bronchopulmonary penicilliosis or chronic allergic sinusitis.
- Scopulariopsis spp. can cause pulmonary infections, fungus balls, and rarely invasive fungal disease. However, its presence usually represents a contaminant. Two or more successive specimens should reflect the presence of this mold before its potential as a pathogenic agent should be considered.
- Paecilomyces can cause endocarditis and fungemia.
- Acremonium spp. is a rare cause of infection.
