Análisis retrospectivo del rendimiento de Amplicor-PCR® para la detección de Mycobacterium tuberculosis en muestras respiratorias y no respiratorias con baciloscopia negativa: A retrospective analysis

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Introducción: Los métodos comerciales de reacción de polimerasa en cadena (RPC) están validados para el diagnóstico de Mycobacterium tuberculosis sólo en muestras respiratorias con baciloscopia positiva. En muestras con baciloscopia negativa, la sensibilidad es variable. Objetivo: Evaluar el comportamiento de la RPC en uso en muestras con baciloscopia negativa. Método: Se compararon los resultados de 235 muestras analizadas por cultivo en agar Loewenstein-Jensen ("estándar de oro") y RPC (AMPLICOR MTB test®, Roche). Resultados: Se analizaron 181 muestras respiratorias y 54 muestras extra-respiratorias. La sensibilidad de la RPC fue de 88 y 50%), respectivamente, la especificidad y el VPP fueron, en ambos casos, de 100%o, y el VPN fue de 99,4%o en muestras respiratorias y de 96,1%) en extra-respiratorias. Conclusiones: El buen desempeño de esta RPC en muestras respiratorias con baciloscopia negativa permite al médico clínico tomar decisiones en base al resultado de este examen, fundamentadamente. En muestras extra-respiratorias, sólo pueden sacarse conclusiones frente a resultados de RPC positivos.

Translated abstract

Background: Commercial polymerase chain reaction (PCR) kits are widely accepted for analysis of smear positive respiratory specimens, but the sensitivity is variable for smear negative ones. Objective: To assess the PCR method usefulness in smear negative respiratory and non respiratory specimens. Methods: We compared the PCR results (AMPLICOR MTB test™, Roche) of 235 specimens subjected to culture in Loewenstein-Jensen agar (as the gold standard). Results: 181 (76%) were respiratory and 54 (24%) extra-respiratory specimens. The sensitivity was 88%) and 50%>, respectively, specificity and PPV was 100%> in both cases. NPV was 99.4%> in respiratory specimens and 96.1% in non-respiratory specimens. Conclusions: The good performance of this PCR in smear negative respiratory specimens allows the clinician to take decisions based on the result of this exam. In extra-respiratory specimens the contribution is important only when the PCR result is positive.

Related collections

Most cited references 61

Record: found
Abstract: found
Article: not found

Rapid diagnosis of extrapulmonary tuberculosis by PCR: impact of sample preparation and DNA extraction.

H. Herrmann, P Lagrange, S Honore … (2003)

In cases of suspected extrapulmonary tuberculosis, rapid and accurate laboratory diagnosis is of prime importance, since traditional techniques of detecting acid-fast bacilli have limitations. The major difficulty with mycobacteria is achieving optimal cell lysis. Buffers used in commercial kits do not allow this complete lysis in a number of clinical specimens. A comparison of two sample preparation methods, pretreatment with proteinase K (PK-Roche) and complete DNA purification (cetyltrimethylammonium bromide [CTAB]-Roche), was conducted on 144 extrapulmonary specimens collected from 120 patients to evaluate the impact on the Cobas-Amplicor method. Thirty patients were diagnosed with tuberculosis, with 15 patients culture positive for Mycobacterium tuberculosis. Amplification and detection of the amplicons were impaired by a high number of inhibitory specimens (39 to 52%). CTAB-Roche allowed the detection of more culture-positive specimens by PCR than PK-Roche. Comparison with the final diagnoses of tuberculosis confirmed that CTAB-Roche produced the best sensitivity (53.8%) compared to culture (43.3%), PK-Roche (16%), and smear (13%). However, the specificity of the PCR assay with CTAB-Roche-extracted material was always lower (78.8%) than those with culture (100%) and PK-Roche (96.5%). False-positive specimens were lung biopsy material, lymph node biopsy material and aspirate, or bone marrow aspirate, mainly from immunocompromised patients. Despite the efficiency of complete DNA extraction for the rapid diagnosis by PCR of extrapulmonary tuberculosis, the false-positive results challenge our understanding of PCR results.

0 comments Cited 49 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Assessment by meta-analysis of PCR for diagnosis of smear-negative pulmonary tuberculosis.

K Weigle, Olga L. Sarmiento, Janet Alexander … (2003)

We conducted a meta-analysis to assess the performance of PCR for the diagnosis of smear-negative pulmonary tuberculosis (SPT) and to identify factors that account for differences in the diagnostic accuracy of different studies. Studies published before February 2002 were included if sensitivity and specificity of PCR in smear-negative respiratory or gastric-aspirate specimens could be calculated. Analysis was conducted by using summary receiver operating characteristics models. Sensitivity and specificity ranged from 9 to 100% and from 25 to 100%, respectively. Fewer than 40% of the 50 studies reported results by number of patients, reported clinical characteristics of patients, or used as a reference standard combined culture and clinical criteria. Studies that included bronchial specimens showed higher accuracy than studies that evaluated only sputum specimens or included gastric aspirates. Studies that did not report that tests were applied blindly showed higher accuracy than those reporting blind testing. Increased sensitivity due to the use of DNA purification methods was associated with decreased specificity. Studies published after 1995, using Amplicor or dUTP-UNG, were associated with an increase in specificity at the expense of lower sensitivity. We concluded that PCR is not consistently accurate enough to be routinely recommended for the diagnosis of SPT. However, PCR of bronchial specimens could be useful in highly suspicious SPT cases. Studies not reporting blind testing are likely to overestimate accuracy of PCR. Future evaluation of PCR accuracy should be conducted by patient and type of respiratory specimen, blindly, by using a reference standard that combines culture and clinical criteria and addresses the issue of how patient characteristics affect PCR accuracy.

0 comments Cited 49 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Commercial Nucleic-Acid Amplification Tests for Diagnosis of Pulmonary Tuberculosis in Respiratory Specimens: Meta-Analysis and Meta-Regression

Daphne I Ling, Laura L Flores, Lee W Riley … (2008)

Background Hundreds of studies have evaluated the diagnostic accuracy of nucleic-acid amplification tests (NAATs) for tuberculosis (TB). Commercial tests have been shown to give more consistent results than in-house assays. Previous meta-analyses have found high specificity but low and highly variable estimates of sensitivity. However, reasons for variability in study results have not been adequately explored. We performed a meta-analysis on the accuracy of commercial NAATs to diagnose pulmonary TB and meta-regression to identify factors that are associated with higher accuracy. Methodology/Principal Findings We identified 2948 citations from searching the literature. We found 402 articles that met our eligibility criteria. In the final analysis, 125 separate studies from 105 articles that reported NAAT results from respiratory specimens were included. The pooled sensitivity was 0.85 (range 0.36–1.00) and the pooled specificity was 0.97 (range 0.54–1.00). However, both measures were significantly heterogeneous (p<.001). We performed subgroup and meta-regression analyses to identify sources of heterogeneity. Even after stratifying by type of commercial test, we could not account for the variability. In the meta-regression, the threshold effect was significant (p = .01) and the use of other respiratory specimens besides sputum was associated with higher accuracy. Conclusions/Significance The sensitivity and specificity estimates for commercial NAATs in respiratory specimens were highly variable, with sensitivity lower and more inconsistent than specificity. Thus, summary measures of diagnostic accuracy are not clinically meaningful. The use of different cut-off values and the use of specimens other than sputum could explain some of the observed heterogeneity. Based on these observations, commercial NAATs alone cannot be recommended to replace conventional tests for diagnosing pulmonary TB. Improvements in diagnostic accuracy, particularly sensitivity, need to be made in order for this expensive technology to be worthwhile and beneficial in low-resource countries.

0 comments Cited 46 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Journal

Journal ID (publisher-id): rci

Title: Revista chilena de infectología

Abbreviated Title: Rev. chil. infectol.

Publisher: Sociedad Chilena de Infectología (Santiago, , Chile )

ISSN (Print): 0716-1018

Publication date (Print and electronic): December 2009

Volume: 26

Issue: 6

Pages: 495-498

Affiliations

[01] Santiago orgnamePontificia Universidad Católica de Chile orgdiv1Facultad de Medicina orgdiv2Departamento de Laboratorios Clínicos Chile

Article

Publisher ID: S0716-10182009000700001 Publisher ID: S0716-1018(09)02600601

DOI: 10.4067/S0716-10182009000700001

SO-VID: d09f6a54-dbf4-4c29-b62a-621c09248c07

License:

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

History

Date received : 16 April 2009

Date accepted : 05 October 2009

Page count

Figures: 0, Tables: 0, Equations: 0, References: 34, Pages: 4

Product

SciELO Chile

Read this article at

Abstract

Translated abstract

Related collections

SciELO Chile

Most cited references 61

Rapid diagnosis of extrapulmonary tuberculosis by PCR: impact of sample preparation and DNA extraction.

Assessment by meta-analysis of PCR for diagnosis of smear-negative pulmonary tuberculosis.

Commercial Nucleic-Acid Amplification Tests for Diagnosis of Pulmonary Tuberculosis in Respiratory Specimens: Meta-Analysis and Meta-Regression

Author and article information

Journal

Affiliations

Article

History

Page count

Product

Categories

Comments

Comment on this article

Similar content 108

Most referenced authors 339