The American journal of tropical medicine and hygiene
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Am. J. Trop. Med. Hyg. · Oct 2014
Standardization of a TaqMan-based real-time PCR for the detection of Mycobacterium tuberculosis-complex in human sputum.
Real-time polymerase chain reaction (qPCR) was optimized for detecting Mycobacterium tuberculosis in sputum. Sputum was collected from patients (N = 112) with suspected pulmonary tuberculosis, tested by smear microscopy, decontaminated, and split into equal aliquots that were cultured in Löwenstein-Jensen medium and tested by qPCR for the small mobile genetic element IS6110. The human ERV3 sequence was used as an internal control. 3 of 112 (3%) qPCR failed. ⋯ The qPCR was negative for 24 of 25 of the sputa with negative microscopy and culture (diagnostic specificity 96%). The qPCR had 99.5% sensitivity and specificity for 211 quality control samples including 84 non-tuberculosis mycobacteria. The qPCR cost ∼5US$ per sample and provided same-day results compared with 2-6 weeks for culture.
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A 42-year-old male presented in June of 2011 with nocturnal fevers, night sweats, an 8-kg weight loss, and a cutaneous right chest wall mass. In March of 2013, a computed tomographic scan of the thorax showed a 54 × 18 × 26-mm right lower lobe mass with peripheral calcifications, and in May of 2013, he was admitted for a segmental lobectomy, in which histologic examination of the pulmonary tissue revealed granulomas with multinucleated giant cells. The tissue was negative for acid-fast bacillae on Ziehl-Neelsen stain, and culture grew Mycobacterium tuberculosis. Therefore, he was started on four first-line antituberculosis medications and showed rapid symptomatic improvement.