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Diagnostic accuracy of Xpert(®) MTB/RIF on bronchoscopy specimens in patients with suspected pulmonary tuberculosis.

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Diagnostic accuracy of Xpert(®) MTB/RIF on bronchoscopy specimens in patients with suspected pulmonary tuberculosis.

Int J Tuberc Lung Dis. 2013 Apr 23;

Authors: Lee HY, Seong MW, Park SS, Hwang SS, Lee J, Park YS, Lee CH, Lee SM, Yoo CG, Kim YW, Han SK, Yim JJ

Abstract
OBJECTIVE: To determine the diagnostic accuracy of the Xpert(®) MTB/RIF assay using samples obtained through bronchoscopy in patients with suspected pulmonary tuberculosis (PTB).DESIGN: We retrospectively reviewed the records of patients with suspected PTB for whom the Xpert MTB/RIF assay was performed on bronchoscopy specimens. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of active PTB were calculated for acid-fast bacilli (AFB) smear microscopy and the Xpert assay using culture of Mycobacterium tuberculosis from sputum or bronchoscopy specimens as a reference standard.RESULTS: A total of 132 patients were included in the final analysis. Of these, 38 had culture-confirmed PTB. The sensitivity of the Xpert assay using bronchial washing or bronchoalveolar lavage (BAL) fluid for the diagnosis of PTB was 81.6%, and specificity was 100%. The PPV and NPV were 100% and 92.1%, respectively. The sensitivity and specificity of AFB smear microscopy were respectively 13.2% and 98.8%.CONCLUSION: The Xpert assay on bronchoscopy specimens provided an accurate diagnosis of PTB in patients who had a negative AFB smear or who could not produce sputum.

PMID: 23621953 [PubMed - as supplied by publisher]

Modeling the Mycobacterium tuberculosis Granuloma - the Critical Battlefield in Host Immunity and Disease.

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Modeling the Mycobacterium tuberculosis Granuloma - the Critical Battlefield in Host Immunity and Disease.

Front Immunol. 2013;4:98

Authors: Guirado E, Schlesinger LS

Abstract
Granulomas are the hallmark of Mycobacterium tuberculosis (M.tb) infection and thus sit at the center of tuberculosis (TB) immunopathogenesis. TB can result from either early progression of a primary granuloma during the infection process or reactivation of an established granuloma in a latently infected person. Granulomas are compact, organized aggregates of immune cells consisting of blood-derived infected and uninfected macrophages, foamy macrophages, epithelioid cells (uniquely differentiated macrophages), and multinucleated giant cells (Langerhans cells) surrounded by a ring of lymphocytes. The granuloma's main function is to localize and contain M.tb while concentrating the immune response to a limited area. However, complete eradication does not occur since M.tb has its own strategies to persist within the granuloma and to reactivate and escape under certain conditions. Thus M.tb-containing granulomas represent a unique battlefield for dictating both the host immune and bacterial response. The architecture, composition, function, and maintenance of granulomas are key aspects to study since they are expected to have a profound influence on M.tb physiology in this niche. Granulomas are not only present in mycobacterial infections; they can be found in many other infectious and non-infectious diseases and play a crucial role in immunity and disease. Here we review the models currently available to study the granulomatous response to M.tb.

PMID: 23626591 [PubMed]

Advances in the development of new tuberculosis drugs and treatment regimens.

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Advances in the development of new tuberculosis drugs and treatment regimens.

Nat Rev Drug Discov. 2013 May;12(5):388-404

Authors: Zumla A, Nahid P, Cole ST

Abstract
Despite the introduction 40 years ago of the inexpensive and effective four-drug (isoniazid, rifampicin, pyrazinamide and ethambutol) treatment regimen, tuberculosis (TB) continues to cause considerable morbidity and mortality worldwide. For the first time since the 1960s, new and novel drugs and regimens for all forms of TB are emerging. Such regimens are likely to utilize both repurposed drugs and new chemical entities, and several of these regimens are now progressing through clinical trials. This article covers current concepts and recent advances in TB drug discovery and development, including an update of ongoing TB treatment trials, newer clinical trial designs, TB biomarkers and adjunct host-directed therapies.

PMID: 23629506 [PubMed - in process]

Automatic screening for tuberculosis in chest radiographs: a survey.

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Automatic screening for tuberculosis in chest radiographs: a survey.

Quant Imaging Med Surg. 2013 Apr;3(2):89-99

Authors: Jaeger S, Karargyris A, Candemir S, Siegelman J, Folio L, Antani S, Thoma G

Abstract
Tuberculosis (TB) is a major global health threat. An estimated one-third of the world's population has a history of TB infection, and millions of new infections are occurring every year. The advent of new powerful hardware and software techniques has triggered attempts to develop computer-aided diagnostic systems for TB detection in support of inexpensive mass screening in developing countries. In this paper, we describe the medical background of TB detection in chest X-rays and present a survey of the recent approaches using computer-aided detection. After a thorough research of the computer science literature for such systems or related methods, we were able to identify 16 papers, including our own, written between 1996 and early 2013. These papers show that TB screening is a challenging task and an open research problem. We report on the progress to date and describe experimental screening systems that have been developed.

PMID: 23630656 [PubMed - in process]

Comparison of LED and conventional fluorescence microscopy for detection of acid-fast bacilli in an area with high tuberculosis incidence.

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The objective of the study is to compare the performance of conventional fluorescence microscopy (CFM) and light-emitting diode (LED) fluorescence microscopy (FM) for detection of acid-fast bacilli (AFB) in clinical samples.

We included AFB smears, stained using the auramine O method and blindly examined with both CFM and LED-FM. Culture results were used as reference for evaluating the reliability of the FM. We included 180 culture positive specimens and an equal number of culture negative specimens.

Sensitivities for the CFM and LED-FM were 79.4% and 82.2%, respectively. Both microscopes had a high specificity (97.2%). The negative-positive (>1 cross) inter-reader agreement of LED-FM and CFM was excellent. Therefore, detection of scanty AFB was higher with LED-FM. Both microscopes were equivalent with respect to time required to read smears.

Although it was not faster than CFM, the higher detection of scanty AFB smears combined with ease of use supports the consideration of LED microscopy by all tuberculosis diagnostic laboratories, as a replacement for conventional fluorescence microscopes.

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