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Screening of tuberculosis suspected subjects using real-time PCR, TaqMan method; Northeastern Iran
Sanaz Ahmadi Ghezeldasht1, Arman Mosavat1, Saman Soleimanpour2
1Blood Borne Infections Research Center, Academic Center for Education, Culture, and Research (ACECR), Razavi Khorasan, Mashhad, Iran.
Journal of Infection and Public Health
|August 19, 2025
Summary
Real-time PCR (qPCR) identified 13.55% of tuberculosis (TB) cases missed by conventional smear microscopy and culture. This molecular diagnostic method offers a practical and time-saving approach for TB detection, especially for extrapulmonary samples.
Area of Science:
- Medical Diagnostics
- Microbiology
- Molecular Biology
Background:
- Effective tuberculosis (TB) treatment relies on rapid and accurate diagnostic techniques for global disease control.
- Conventional sputum smear microscopy and culture methods have limitations in detecting all TB cases.
Purpose of the Study:
- To evaluate the diagnostic performance of a laboratory-developed real-time PCR (qPCR) assay.
- To determine the number of presumptive TB patients missed by conventional diagnostic methods.
Main Methods:
- A cross-sectional study involving 307 presumptive TB subjects with negative smear microscopy and culture results.
- Evaluation using an in-house TaqMan real-time PCR (qPCR) assay.
- Comparison with conventional Ziehl-Neelsen (ZN) staining microscopy and culture.
Main Results:
- qPCR detected 13.55% (50/307) of TB cases missed by conventional methods.
- In urine samples, qPCR identified 30% (6/20) of positive cases, whereas microscopy and culture yielded no positive results.
- qPCR demonstrated 100% sensitivity and 83.7% specificity in TB diagnosis.
Conclusions:
- In-house qPCR assays are practical, time-saving, and feasible for diagnosing TB.
- qPCR is particularly effective for extrapulmonary TB forms, including urine, CSF, and paraffin-embedded samples.
- This molecular technique surpasses direct microscopy and culture in detecting certain TB cases.
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