Evaluation of sputum decontamination methods for Mycobacterium tuberculosis using viable colony counts and flow cytometry

Burdz, Tamara; Wolfe, Jonathan; Kabani, Amin

doi:10.1016/s0732-8893(03)00138-x

Cited by 42 publications

(32 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the studies reported earlier (Burdz et al, 2003;Middlebrook et al, 1977;Shah et al, 1985) as well as ours, visual method appears to detect few samples more than that detected by radiometric method. The reason for this discrepancy is not known.…”

Section: Discussionsupporting

confidence: 79%

Evaluation of Radiorespirometric Technique for Detection of Mycobacterium Tuberculosis Strains From Pulmonary Tuberculosis Patients

Vaidya

Huliyalkar

Gohil

et al. 2017

Lijhls

View full text Add to dashboard Cite

show abstract

Section: Discussionsupporting

confidence: 79%

Evaluation of Radiorespirometric Technique for Detection of Mycobacterium Tuberculosis Strains From Pulmonary Tuberculosis Patients

Vaidya

Huliyalkar

Gohil

et al. 2017

Lijhls

View full text Add to dashboard Cite

show abstract

“…The correlation between Ct and MGIT TTD was relatively stronger although complicated by nonstandardized reporting of contaminated samples and the fact that TTD was reported in days rather than hours. Variability in the NALC-NaOH decontamination procedure can introduce significant variation in the percentage of viable cells recovered from a processed sputum sample (26). The combination of variability in postdecontamination viability and strain-specific differences in growth rate all likely contributed to the variation in M. tuberculosis Cts observed for samples positive by MGIT on the same day.…”

Section: Discussionmentioning

confidence: 99%

A Multisite Assessment of the Quantitative Capabilities of the Xpert MTB/RIF Assay

Blakemore¹,

Nabeta

Davidow³

et al. 2011

Am J Respir Crit Care Med

108

View full text Add to dashboard Cite

Rationale: The Xpert MTB/RIF is an automated molecular test for Mycobacterium tuberculosis that estimates bacterial burden by measuring the threshold-cycle (Ct) of its M. tuberculosis-specific real-time polymerase chain reaction. Bacterial burden is an important biomarker for disease severity, infection control risk, and response to therapy. Objectives: Evaluate bacterial load quantitation by Xpert MTB/RIF compared with conventional quantitative methods. Methods: Xpert MTB/RIF results were compared with smear-microscopy, semiquantiative solid culture, and time-to-detection in liquid culture for 741 patients and 2,008 samples tested in a multisite clinical trial. An internal control real-time polymerase chain reaction was evaluated for its ability to identify inaccurate quantitative Xpert MTB/RIF results. Measurements and Main Results: Assays with an internal control Ct greater than 34 were likely to be inaccurately quantitated; this represented 15% of M. tuberculosis-positive tests. Excluding these, decreasing M. tuberculosis Ct was associated with increasing smear microscopy grade for smears of concentrated sputum pellets (r s ¼ 20.77) and directly from sputum (r s ¼ 20.71). A Ct cutoff of approximately 27.7 best predicted smear-positive status. The association between M. tuberculosis Ct and time-to-detection in liquid culture (r s ¼ 0.68) and semiquantitative colony counts (r s ¼ 20.56) was weaker than smear. Tests of paired same-patient sputum showed that highviscosity sputum samples contained 332 more M. tuberculosis than nonviscous samples. Comparisons between the grade of the acid-fast bacilli smear and Xpert MTB/RIF quantitative data across study sites enabled us to identify a site outlier in microscopy. Conclusions: Xpert MTB/RIF quantitation offers a new, standardized approach to measuring bacterial burden in the sputum of patients with tuberculosis.Keywords: tuberculosis; molecular diagnostics; diagnostic techniques and procedures; diagnosis; clinical trial Measurements of bacterial load have long played an important role in tuberculosis diagnostics. Semiquantitative or quantitative measures of the number of Mycobacterium tuberculosis bacilli present within a clinical sample have been clinically useful for determining disease severity, assessing transmission risk, or monitoring therapy (1-3). Quantitative readouts have also aided in the investigation of potentially false-positive results (4-6).The Xpert MTB/RIF (Cepheid, Sunnyvale, CA) assay simultaneously detects the presence of M. tuberculosis and its susceptibility to the important first-line drug rifampin in less than 2 hours (7). The assay is contained in a small plastic cartridge, and it is run on the GeneXpert platform (Cepheid), a diagnostic The Xpert MTB/RIF assay is a rapid diagnostic test for tuberculosis and rifampin resistance. A number of studies have examined the sensitivity and specificity of the assay in various clinical settings and with various sample types. The test can also provide an estimate of the bacterial load present in the s...

show abstract

“…Due to the paucibacillary nature of specimens from children, it is possible that decontamination conditions that are too stringent may easily render the small concentration of organisms present nonviable for culture (16). Mycobacterial culture can be performed on either a solid or a liquid medium.…”

Section: Culture Detection Methodsmentioning

confidence: 99%

Laboratory Diagnosis of Mycobacterium tuberculosis Infection and Disease in Children

2016

View full text Add to dashboard Cite

Diagnosis of tuberculosis in children is challenging; even with advanced technologies, the diagnosis is often difficult to confirm microbiologically in part due to the paucibacillary nature of the disease. Clinical diagnosis lacks standardization, and traditional and molecular microbiologic methods lack sensitivity, particularly in children. Immunodiagnostic tests may improve sensitivity, but these tests cannot distinguish tuberculosis disease from latent infection and some lack specificity. While molecular tools like Xpert MTB/RIF have advanced our ability to detectMycobacterium tuberculosisand to determine antimicrobial resistance, decades old technologies remain the standard in most locales. Today, the battle against this ancient disease still poses one of the primary diagnostic challenges in pediatric laboratory medicine.

show abstract

Evaluation of sputum decontamination methods for Mycobacterium tuberculosis using viable colony counts and flow cytometry

Cited by 42 publications

References 18 publications

Evaluation of Radiorespirometric Technique for Detection of Mycobacterium Tuberculosis Strains From Pulmonary Tuberculosis Patients

Evaluation of Radiorespirometric Technique for Detection of Mycobacterium Tuberculosis Strains From Pulmonary Tuberculosis Patients

A Multisite Assessment of the Quantitative Capabilities of the Xpert MTB/RIF Assay

Laboratory Diagnosis of Mycobacterium tuberculosis Infection and Disease in Children

Contact Info

Product

Resources

About