Performance of a Highly Sensitive Mycobacterium tuberculosis Complex Real-Time PCR Assay for Diagnosis of Pulmonary Tuberculosis in a Low-Prevalence Setting: a Prospective Intervention Study

ABSTRACT The potential impact of routine real-time PCR testing of respiratory specimens from patients with presumptive tuberculosis in terms of diagnostic accuracy and time to tuberculosis treatment inception in low-prevalence settings remains largely unexplored. We conducted a prospective intervention cohort study. Respiratory specimens from 1,020 patients were examined by acid-fast bacillus smear microscopy, tested by a real-time Mycobacterium tuberculosis complex PCR assay (Abbott RealTi me MTB PCR), and cultured in mycobacterial media. Seventeen patients tested positive by PCR (5 were acid-fast bacillus smear positive and 12 acid-fast bacillus smear negative), and Mycobacterium tuberculosis was recovered from cultures for 12 of them. Patients testing positive by PCR and negative by culture ( n = 5) were treated and deemed to have responded to antituberculosis therapy. There were no PCR-negative/culture-positive cases, and none of the patients testing positive for nontuberculous mycobacteria ( n = 20) yielded a positive PCR result. The data indicated that routine testing of respiratory specimens from patients with presumptive tuberculosis by the RealTi me MTB PCR assay improves the tuberculosis diagnostic yield and may reduce the time to antituberculosis treatment initiation. On the basis of our data, we propose a novel mycobacterial laboratory algorithm for tuberculosis diagnosis.

Value of bronchoscopy in the diagnosis of sputum smear negative pulmonary tuberculosis

Background: Bronchoscopy has been found to be applicable in diagnosing suspects of pulmonary TB which have no sputum or sputum smear negative for acid fast bacilli. Additionally, it is helpful in the diagnosis of endobronchial tuberculosis, allowing early detection of broncho stenosis.Methods: A prospective study, where bronchoscopy was conducted in 167 patients with acid-fast bacillus sputum smear negative. The average age of the patients was 44.1±19.4, from age 15 to 87 years old, higher frequency in age from 20-40 years old and 55-64 years old.Results: From 167 patients in the study, endoscopic presentation resulted: normal in 7 (4.2%) cases, bronchitis - 60 (35.9%) cases, oedematous-hyperaemic -62 (37.1%) cases, caseous inflammation - 7 (4.2%) cases, ulcerative lesions - 3 (1.8%) cases, tumoral lesions - 21 (12.6%) cases and fibrous stenotic changes in 7 (4.2%) patients. From 44 (26.3%) patients to whom was obtained biopsy, the histological examination has resulted: 24 (54.5%) cases with TB granuloma, 14 (31.8%) - epithelioid granulomas and in 6 (13.6%) cases resulted non-specific inflammation. The examination of bronchial washing for acid-fast bacillus smear concluded the diagnosis in 40.4% of cases, the examination for acid-fast bacillus smear collected after diagnostic FBS has been decisive in 53.9% of cases. The examination for acid-fast bacillus culture resulted positive in 70.5% of bronchial washing and in 61.2% of sputum collected after FBS.Conclusions: Fibreoptic bronchoscopy plays the key role to the patients with suspected tuberculosis which are acid-fast bacillus smear negative or that have no sputum.

Multicenter Evaluation of Anyplex Plus MTB/NTM MDR-TB Assay for Rapid Detection of Mycobacterium tuberculosis Complex and Multidrug-Resistant Isolates in Pulmonary and Extrapulmonary Specimens

The rapid diagnosis of tuberculosis (TB) and the detection of drug-resistantMycobacterium tuberculosisstrains are critical for successful public health interventions. Therefore, TB diagnosis requires the availability of diagnostic tools that allow the rapid detection ofM. tuberculosisand drug resistance in clinical samples. Here, we performed a multicenter study to evaluate the performance of the Seegene Anyplex MTB/NTM MDR-TB assay, a new molecular method based on a multiplex real-time PCR system, for detection ofMycobacterium tuberculosiscomplex (MTBC), nontuberculous mycobacteria (NTM), and genetic determinants of drug resistance. In total, the results for 755 samples (534 pulmonary and 221 extrapulmonary samples) were compared with the results of smears and cultures. For pulmonary specimens, the sensitivities of the Anyplex assay and acid-fast bacillus smear testing were 86.4% and 75.0%, respectively, and the specificities were 99% and 99.4%. For extrapulmonary specimens, the sensitivities of the Anyplex assay and acid-fast bacillus smear testing were 83.3% and 50.0%, respectively, and the specificities of both were 100%. The negative and positive predictive values of the Anyplex assay for pulmonary specimens were 97% and 100%, respectively, and those for extrapulmonary specimens were 84.6% and 100%. The sensitivities of the Anyplex assay for detecting isoniazid resistance in MTBC strains from pulmonary and extrapulmonary specimens were 83.3% and 50%, respectively, while the specificities were 100% for both specimen types. These results demonstrate that the Anyplex MTB/NTM MDR-TB assay is an efficient and rapid method for the diagnosis of pulmonary and extrapulmonary TB and the detection of isoniazid resistance.

Evaluation of the Cobas TaqMan MTB Test for the Detection of Mycobacterium tuberculosis Complex According to Acid-Fast-Bacillus Smear Grades in Respiratory Specimens

We evaluated the performance of the Cobas TaqMan MTB test (Roche Diagnostics, Basel, Switzerland), stratified by acid-fast bacilli (AFB) smear grades. The sensitivity of this test in smear-positive specimens was >95% in all grades, while that in trace and negative specimens was 85.3% and 34.4%, respectively.

Evaluation ofhsp65Nested PCR-Restriction Analysis (PRA) for Diagnosing Tuberculosis in a High Burden Country

Current study evaluated thehsp65Nested PCR Restriction Fragment Length Polymorphism Analysis (hsp65Nested PCR-PRA) to detect and identifyMycobacterium tuberculosiscomplex directly in clinical samples for a rapid and specific diagnosis of tuberculosis (TB).hsp65Nested PCR-PRA was applied directly to 218 clinical samples obtained from 127 patients suspected of TB or another mycobacterial infection from July 2009 to July 2010. Thehsp65Nested PCR-PRA showed 100% sensitivity and 95.0 and 93.1% specificity in comparison with culture and microscopy (acid fast bacillus smear), respectively.hsp65Nested PCR-PRA was shown to be a fast and reliable assay for diagnosing TB, which may contribute towards a fast diagnosis that could help the selection of appropriate chemotherapeutic and early epidemiological management of the cases which are of paramount importance in a high TB burden country.

Association between tobacco smoking and pulmonary tuberculosis

Background/Aim. Numerous studies evaluate the influence of tobacco smoking on the tuberculosis (TB) development, with the results indicating that smoking can be also considered as important risk factor in TB. The aim of this study was to assess the influence of tobacco smoking as the risk factor in the development of TB as well as in its clinical course. Methods. We analyzed data from the medical records of 192 consecutively hospitalized TB patients (124 males and 68 females) in the Institute of Pulmonary Diseases and Tuberculosis, Clinical Center of Serbia, Belgrade in the period from 2005 to 2007. Results. Among the analyzed TB patients there were more smokers (63.5%) than nonsmokers (36.5%). The majority of the smokers (73.8%) belonged to a middle age group (35-54 years) while the majority of nonsmokers (64.3%) were older than 55 years. Sex ratio among the smokers showed the domination of males (80.3%). There were significantly more males in the smoking group and more females in the nonsmoking group (?2 = 34.402, p < 0.0001). Most smokers (68.9%) smoked more than 20 cigarettes daily. The average index of pack/years among all of the examinated patients was 32.75 ? 18.26. Cavitary pulmonary lesions were more frequently verified in the smokers (64.2%) than in the nonsmokers (35.8%). The sputum acid-fast bacillus smear-positive finding was more frequent in the smokers (78%) than in the nonsmokers (22%). The nonsmoking TB patients had more accompanied immunodeficient diseases (34%) than the smoking ones (19%). Body-mass index was lower in the smokers (21.75) than in the nonsmokers (23.80), although this difference did not reach the statistical significance. Conclusion. There are more smokers than nonsmokers in TB patients. Smokers more frequently have cavitary forms of TB with sputum acid-fast bacillus smear - positive finding than nonsmokers.