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Published on: July 9, 2014
Application of nested PCR for diagnosis of histoplasmosis
Hideaki Ohno1, Koichi Tanabe, Takashi Umeyama
1Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo, 162-8640, Japan, h-ohno@nih.go.jp.
Abstract:
Histoplasmosis is a fungal infection that, although not endemic in Japan, has seen a rise in the number of Japanese cases since the mid-1980s. Diagnosis of the disease is not straightforward, and the main method of detection, fungal culture (which has biosafety-related issues), is of low sensitivity in general. Alternative methods that depend on antibody or antigen detection have had limited use. We have developed a histoplasmosis detection method based on PCR amplification of the Histoplasma capsulatum M antigen gene. We compared this method with fungal culture and serological diagnostic techniques. Among five cases that were finally diagnosed as histoplasmosis, the fungal culture method was only successful in identifying one such case. Although the presence of anti-H. capsulatum antibodies was confirmed in three cases, our PCR method identified four of five cases of histoplasmosis. The performance of our PCR method could not be compared with the antigen detection method, which is used in the United States but is not routinely used in Japan. However, the PCR method was shown to have high sensitivity and specificity for H. capsulatum. Although the number of histoplasmosis cases examined in this study was small, our data suggest that the molecular diagnosis technique has potential for increasing the reliability of histoplasmosis diagnosis when used in combination with established methods.
Insights
A new PCR test shows promise for diagnosing histoplasmosis, a fungal infection. This molecular method offers higher sensitivity than traditional fungal cultures and antibody tests, improving diagnostic reliability.
Area of Science:
- Medical Mycology
- Molecular Diagnostics
- Infectious Diseases
Background:
- Histoplasmosis, a fungal infection, is increasingly diagnosed in Japan despite not being endemic.
- Current diagnostic methods like fungal culture have low sensitivity and biosafety concerns.
- Serological antibody and antigen detection methods have limited utility.
Purpose of the Study:
- To develop and evaluate a novel PCR-based method for detecting Histoplasma capsulatum.
- To compare the efficacy of the PCR method against conventional diagnostic techniques.
Main Methods:
- Developed a PCR assay targeting the M antigen gene of Histoplasma capsulatum.
- Compared PCR results with fungal culture and serological antibody detection in five histoplasmosis cases.
Main Results:
- The PCR method identified 4 out of 5 histoplasmosis cases, outperforming fungal culture (1/5).
- Serological tests confirmed antibodies in 3 out of 5 cases.
- The PCR assay demonstrated high sensitivity and specificity for Histoplasma capsulatum.
Conclusions:
- PCR-based molecular diagnosis offers a more sensitive and reliable approach for histoplasmosis detection.
- This technique has the potential to enhance diagnostic accuracy when integrated with existing methods.
