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Updated: Jun 6, 2026
Passive Administration of Monoclonal Antibodies Against H. capsulatum and Others Fungal Pathogens
Published on: February 14, 2011
[Rapid identification of Histoplasma capsulatum in culture lysates]
Belén Ibarra-Camou1, Adriana Inés Toranzo, William Lee
1Departamento de Micología, INEI-ANLIS Dr. Carlos G. Malbrán, Buenos Aires, Argentina.
Background:
Histoplasma capsulatum is the agent of histoplasmosis, a deep mycosis mainly afflicting immunocompromised patients. Rapid identification of the fungus isolated from clinical specimens allows timely administration of specific treatment.
Aim:
To assess the ability of a dual PCR system targeting specific H. capsulatum DNA sites to identify fungal species in simple aqueous lysates from cultured fungi.
Methods:
We analysed the performance of two independent PCR reactions designed to amplify fragments of 111 and 279 bp included in H. capsulatum-specific gene AgM. We used 248 H. capsulatum strains and 68 isolates of other fungal species. Reaction templates consisted of aqueous lysates of cultured fungi (either in mycelial or yeast phase) obtained after three cycles of boiling and immediate cooling at 0°C. Selected strains were submitted to conventional DNA extraction and/or sequencing.
Results:
Both PCR systems performed identically. Amplification from aqueous lysates was achieved from 239 H. capsulatum strains; the remaining 9 strains only showed specific bands when purified DNA was used as template. Of all other fungal species tested, only 2 Emmonsia crescens strains amplified H. capsulatum-specific bands and sequences of their amplified PCR products matched > 97% with H. capsulatum sequences. Total test time did not exceed 7h with 96% sensitivity, 97% specificity and 99% positive predictive value.
Conclusions:
The assay is fast, accurate and economical, and can be an alternative method for presumptive identification of H. capsulatum in simple culture lysates.
Insights
A new dual PCR method accurately identifies Histoplasma capsulatum in simple fungal lysates within 7 hours. This rapid and economical assay aids in timely diagnosis of histoplasmosis, especially in immunocompromised patients.
Area of Science:
- Medical Mycology
- Molecular Diagnostics
- Infectious Diseases
Background:
- Histoplasma capsulatum causes histoplasmosis, a significant mycosis affecting immunocompromised individuals.
- Timely identification of H. capsulatum is crucial for effective treatment of histoplasmosis.
Purpose of the Study:
- To evaluate a dual PCR system for identifying H. capsulatum DNA in simple aqueous fungal lysates.
- To assess the diagnostic performance of PCR targeting specific H. capsulatum gene AgM fragments.
Main Methods:
- Two PCR assays targeting H. capsulatum-specific gene AgM fragments (111 and 279 bp) were developed.
- Aqueous lysates from 248 H. capsulatum strains and 68 other fungal species were tested.
- Performance was assessed using simple boiling-cooling lysis and compared with purified DNA.
Main Results:
- The dual PCR system demonstrated high accuracy, with 96% sensitivity and 97% specificity.
- Amplification from aqueous lysates identified 239 H. capsulatum strains; purified DNA was needed for 9 additional strains.
- Minimal cross-reactivity was observed, with only 2 Emmonsia crescens strains showing partial amplification.
Conclusions:
- The developed PCR assay is a fast, accurate, and economical tool for presumptive identification of H. capsulatum.
- This method offers a valuable alternative for identifying H. capsulatum directly from simple culture lysates.
- The assay's efficiency supports prompt diagnosis and management of histoplasmosis.
