PCR as a Diagnostic Tool for Extra-Pulmonary Tuberculosis

Abstract

Introduction: Extra-Pulmonary Tuberculosis (EPTB) accounts for approximately 40% of the tuberculosis cases. Though it is not communicable, it is a significant cause of morbidity. This study was conducted to know the efficacy of the Polymerase Chain Reaction (PCR) as an additional tool, along with the conventional methods, in the diagnosis of EPTB. Materials and Methods:Clinical samples were collected from suspected cases of EPTB. The Ziehl-Neelsen staining (ZNS), culture on the Lowenstein-Jensen medium (LJM) and PCR testing with the use of a commercial kit were performed on the homogenized samples.Results: A total of 182 samples which were received for the molecular diagnosis of EPTB were also tested by ZNS and culture on LJM for the presence of Mycobacterium tuberculosis. Of these, 22 were positive by at least one of the tests which were used. PCR detected the maximum number of cases of EPTB, followed by culture. The results of PCR and the conventional tests were analyzed by using McNemar's test for the correlated proportions-the exact method of 'IBM SPSS Statistics 20'. The analysis showed a statistical significance.Conclusions: Whenever they are feasible, using all the available tests in combination increases the laboratory detection rates of M. tuberculosis from clinical samples. PCR must be included in the diagnostic panel of EPTB.

Performance of the IS6110-TaqMan® assay in the diagnosis of extrapulmonary tuberculosis from different biological samples

“…When the IS6110-TaqMan ® assay for urine samples was compared with two different gold-standard criteria (1: culture and/or response to antitubercular therapy; 2: culture alone), the sensitivity increased by 15.1% when compared to the gold standard 1. These findings reinforce the limitation of culturing in cases of patients with paucibacillary forms 30,31 . Studies show variability in positive results of the culture test (12% to 80%) in a range of clinical samples and biological tissues 12,15,24 .…”

“…To evaluate the positivity of biological samples, the threshold value of amplification (C t ) was established for positive and negative cases. The resulting C t was 25 (25)(26)(27)(28)(29)(30)(31)(32)(33) and 34 (34)(35)(36)(37)(38) for the positive and negative tests, respectively (data not shown).…”

Rapid Diagnosis of Mediastinal Tuberculosis with Polymerase Chain Reaction Evaluation of Aspirated Material Taken by Endobronchial Ultrasound–Guided Transbronchial Needle Aspiration

“…In the current study, the histopathological and microbiological examinations as well as PCR have to be used and the results need to be carefully correlated with the clinical outcome of disease. 28 …”

The Relevance of Biopsy in Tuberculosis Patients Without Human Immunodeficiency Virus Infection

“…3 In contrast to pulmonary TB, in which clinical samples, such as sputum, are relatively easy to obtain, diagnosing extrapulmonary TB is challenging, because acid-fast bacillus (AFB) stain and AFB culture tests are positive in fewer than 10% and 20% of suspected cases, respectively. 4,5 Thus, administering antitubercular agents in the early stages may sometimes be necessary in cases in which histological findings are eventually compatible with TB-suspected clinical findings.…”