Volume 66, Issue 3 , Pages 268-273, March 2010
Detection of Histoplasma capsulatum DNA in human samples by real-time polymerase chain reaction
Abstract
The main aim of our study was to determine the added value of real-time polymerase chain reaction (PCR) for the diagnosis of Histoplasma capsulatum in routine biologic practice. No amplification signal was observed with the 18 non-H. capsulatum strains used to test the specificity of the protocol. The sensitivity threshold of the real-time PCR assay was about 10 fg of H. capsulatum DNA per microliter, tested with a 10-fold serial dilution of the positive control. We analyzed 348 human samples submitted for the routine diagnosis of systemic mycosis. Real-time PCR using the TaqMan system was evaluated against direct microscopic examination and culture. Among the 341 samples without PCR inhibition (n = 7), 66 tested positive by culture, whereas 74 tested positive by real-time PCR. Sensitivity of the real-time PCR assay was estimated at 95.4% and specificity at 96.0% with respect to culture, widely considered to be the gold standard method; however, the molecular approach in fact produced better sensitivity and specificity results. Moreover, for the 38 samples that tested negative by direct examination but positive by culture, the culture method took a mean of 31 days longer than the PCR method to generate results. The protocol presented here may be very useful for improving routine histoplasmosis diagnosis.
Keywords: Histoplasma capsulatum, Diagnosis, Real-time PCR, Culture, Human samples
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PII: S0732-8893(09)00420-9
doi:10.1016/j.diagmicrobio.2009.10.010
© 2010 Elsevier Inc. All rights reserved.
Volume 66, Issue 3 , Pages 268-273, March 2010
