Performance Assessment of a Nested-PCR Assay (the RAPID BAP-MTB) and the BD ProbeTec ET System for Detection of Mycobacterium tuberculosis in Clinical Specimens

Abstract

The performance of a nested PCR-based assay (the RAPID BAP-MTB; AsiaGen, Taichung, Taiwan) and the BD ProbeTec ET (DTB) system (Becton Dickinson, Sparks, Md.) for detection of Mycobacterium tuberculosis was evaluated with 600 consecutive clinical samples. These samples, including 552 respiratory specimens and 48 nonrespiratory specimens, were collected from 333 patients treated at National Taiwan University Hospital from September to October 2003. The results of both assays were compared to the gold standard of combined culture results and clinical diagnosis. The overall sensitivity and specificity of the RAPID BAP-MTB assay for respiratory specimens were 66.7% and 97.2%, respectively, and for the DTB assay they were 56.7% and 95.3%, respectively. The positive and negative predictive values for the RAPID BAP-MTB were 74.1% and 96.0%, respectively, and for the DTB assay they were 59.6% and 94.7%, respectively. For smear-negative samples, the sensitivity of the RAPID BAP-MTB and DTB assays was 57.1% and 40.5%, respectively. The RAPID BAP-MTB assay produced 14 false-positive results in 14 samples, including one of the six samples yielding Mycobacterium abscessus, one of the six samples yielding Mycobacterium avium intracellulare, one sample from a patient with a history of pulmonary tuberculosis with complete treatment, and three samples from three patients with a previous diagnosis of tuberculosis who were under treatment at the time of specimen collection. Among the 48 nonrespiratory specimens, the RAPID BAP-MTB assay was positive in one biopsy sample from a patient with lumbar tuberculous spondylitis and one pus sample from a patient with tuberculous cervical lymphadenopathy. Our results showed that the RAPID BAP-MTB assay is better than the DTB assay for both respiratory specimens and nonrespiratory specimens. The overall time for processing this assay is only 5 h. In addition, its diagnostic accuracy in smear-negative samples is as high as in smear-positive samples.

Evaluation of rapid GeneXpert MTB/RIF method using DNA tissue specimens of vertebral bones in patients with suspected spondylitis TB

“…19 Various studies observed the results of PCR technique to diagnose extrapulmonary TB. 8,20 Currently, various PCR studies have developed into GeneXpert MTB/RIF method using heminested real-time polymerase chain reaction (PCR) assay. 11,17,21 This system works automatically toward the lysis of bacteria, extraction of the DNA, amplifications, and the detection of amplicon in a single system using a rapid approach.…”

“…Meanwhile, microbiological culture is recognized for having a high sensitivity and specificity value but needed around 14 days to provide results. 8,9 Currently, radiological examination is widely used as an early diagnostic approach for Spondylitis TB due to its ability to directly visualized the physical abnormalities in the vertebral bone. Several techniques that can be performed are X-ray, Computed Tomography Scan (CT scan), and Magnetic Resonance Imaging (MRI).…”

“…Acid fast staining and microbiological culture shall be performed to confirm the infection of M. tuberculosis in suspected cases. 8 Acid fast staining is the rapid screening method to detect M.tb, but is considered weak due to its low sensitivity rate. Meanwhile, microbiological culture is recognized for having a high sensitivity and specificity value but needed around 14 days to provide results.…”

Five Years’ Evaluation of the BD ProbeTec System for the Direct Molecular Detection of Mycobacterium tuberculosis Complex in Respiratory and Nonrespiratory Clinical Samples

“…In previous studies, the sensitivity, the specificity, positive and negative predictive levels of the BD ProbeTec ET were reported within the ranges of 56.7-100, 95.3-100, 59.6-100 and 96-100%, for respiratory, 50-100 and 93.3-98.7, 33.3-80 and 97.8-100%, for nonrespiratory samples, respectively (Abdel-Aziz et al, 2011;Antonenka et al, 2013;Barber, 2008;Barrett et al, 2002;Bergmann and Woods, 1998;Bergmann et al, 2000;Johansen et al, 2002;Karadag et al, 2013;Maugein et al, 2002;Mazzarelli et al, 2003;Pfyffer et al, 1999;Piersimoni et al, 2002;Rüsch-Gerdes and Richter, 2004;Tu et al, 2011;Wang et al, 2004;Wang et al, 2006). In the present study, the corresponding performance values were found as 81.8, 98.3, 85.1 and 97.9%, for respiratory, and 100, 96.2, 64.7 and 100%, for nonrespiratory samples, respectively.…”

Molecular Biological Techniques for Detection of Multidrug Resistant Tuberculosis (MDR) and Extremely Drug Resistant Tuberculosis (XDR) in Clinical Isolates of Mycobacterium tuberculosis

“…Identification of tuberculosis using molecular techniques namely, polymerase chain reaction (PCR), PCR based restriction fragment length polymorphism (PCR-RFLP) and PCR based DNA sequencing are very rapid, more sensitive and reliable when compared to the conventional culture. There are several in house nested PCR (nPCR) standardized for the detection of M. tuberculosis from clinical specimens targeting MPB64 [Therese KL et al, 2005], IS6110 [Wang et al, 2004] and 16S rRNA [Ninet et al, 1996] genes. MPB64 is an immunogenic protein produced by M. tuberculosis and a few strains of M. bovis and BCG strain.…”