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Emerging fungal pathogens: evolving challenges to immunocompromised patients for the twenty-first century
1Immunocompromised Host Section, Pediatric Oncology Branch, National Cancer Institute, Bethesda, Maryland 20892, USA. walsht@pbmac.nci.nih.gov
Abstract:
Opportunistic fungi have emerged during the past decade as important causes of morbidity and mortality in immunocompromised patients. Candida species constitute the third to fourth most common causes of nosocomial blood stream infections, and Aspergillus species have emerged as the most common infectious cause of pneumonic mortality in bone marrow/stem cell transplant recipients. Among HIV-infected patients, meningoencephalitis due to Cryptococcus neoformans ranks among the most common AIDS-defining infections. Hyaline septated filamentous fungi, such as Fusarium species, Acremonium species, Paecilomyces species, and Trichoderma species, are increasingly reported as causing invasive mycoses refractory to conventional therapy. Dematiaceous septated filamentous fungi, such as Pseudallescheria boydii, Bipolaris species, and Cladophialophora bantiana cause pneumonia, sinusitis, and CNS infection unresponsive to current therapy. An increasing number of different members of the class of Zygomycetes are reported as causing lethal infections, despite aggressive medical and surgical interventions. Yet the treatment for zygomycosis has not changed in approximately 40 years. The prevalence of the endemic mycoses, such as those due to Penicillium marneffei, Coccidioides immitis, and Histoplasma capsulatum, has been reported to expand rapidly in response to environmental exposures and increased numbers of vulnerable hosts in endemic regions of the world. Dermatophytoses are occurring with increasing prevalence and morbidity in elderly and immunocompromised patients. As we enter the next millennium, we may anticipate that emergent fungal infections will continue to develop in the settings of permissive environmental conditions, selective antifungal pressure, and an expanding population of immunocompromised hosts.
Insights
Opportunistic fungal infections are rising in immunocompromised patients, causing significant illness and death. New and existing fungal pathogens require urgent development of novel antifungal therapies.
Area of Science:
- Mycology
- Infectious Diseases
- Immunocompromised Host Research
Background:
- Opportunistic fungal infections pose a growing threat to immunocompromised individuals.
- Candida, Aspergillus, Cryptococcus, and Zygomycetes are leading causes of fungal-related morbidity and mortality.
- Emerging fungal pathogens, including Fusarium and dematiaceous fungi, present treatment challenges.
Purpose of the Study:
- To highlight the increasing prevalence and impact of opportunistic fungal infections.
- To underscore the limitations of current antifungal therapies.
- To emphasize the need for new treatment strategies.
Main Methods:
- Review of current literature on opportunistic fungal infections.
- Analysis of epidemiological trends in fungal disease.
- Assessment of treatment outcomes for various mycoses.
Main Results:
- Candida and Aspergillus species are common causes of nosocomial infections and transplant-related mortality.
- Cryptococcus neoformans is a major AIDS-defining infection.
- Invasive mycoses caused by hyaline and dematiaceous fungi, as well as Zygomycetes, are often refractory to treatment.
- Endemic mycoses and dermatophytoses are expanding in prevalence.
Conclusions:
- Emergent fungal infections are increasing due to environmental factors, antifungal pressure, and a growing immunocompromised population.
- Current antifungal treatments are inadequate for many emerging and established opportunistic mycoses.
- There is a critical need for the development of novel antifungal agents and therapeutic approaches.