Proficiency testing of conventional drug susceptibility tests of Mycobacterium tuberculosis

1987 ◽  
Vol 33 (12) ◽  
pp. 1064-1068 ◽  
Author(s):  
Adalbert Laszlo ◽  
Dorothy M. Helbecque ◽  
Walter Tostowaryk
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Proficiency Testing ◽  
Susceptibility Testing ◽  
Developed Countries ◽  
Drug Susceptibility ◽  
Reference Laboratory ◽  
In Vitro Susceptibility ◽  
Testing Procedures ◽  
Drug Concentrations ◽  
Susceptibility Tests

Proficiency testing of indirect drug susceptibility tests of Mycobacterium tuberculosis was begun in 1985 by the Laboratory Centre for Disease Control (LCDC) with the participation of Provincial Public Health Laboratories in Canada. Comparable sets of 60 cultures of Mycobacterium tuberculosis representing 30 strains were distributed by LCDC to the participating laboratories to be tested for drug susceptibility against isoniazid, streptomycin, rifampin, and ethambutol using conventional methodologies. Intralaboratory agreement values determined by comparing results obtained on sets of duplicate cultures were high and were found to vary little from drug to drug and from laboratory to laboratory. Interlaboratory agreement was determined by comparing results reported by participating laboratories to those obtained by the Reference Laboratory. Agreement percentages were found to be lower for drug-resistant cultures than for drug-susceptible cultures. The reliability of drug susceptibility testing results was higher for isoniazid and rifampin, than for ethambutol and streptomycin. This study shows that the higher subsidiary drug concentrations do not compare well with main drug concentrations, especially in the case of streptomycin and ethambutol. The significance of the higher subsidiary concentrations in in vitro susceptibility testing is therefore in need of clarification. The proficiency testing results obtained in this study compare favorably with those reported in other developed countries despite the fact that a variety of testing procedures are used throughout the country.

scholarly journals Comparison between the conventional method and molecular line probe assay for identification and drug sensitivity of mycobacteria tuberculosis from clinical specimens

2014 ◽  
Vol 2 (03) ◽  
pp. 80-83
Author(s):  
Ritu Kansal ◽  
Molly Madan ◽  
Richa Kansal ◽  
Vivek Agwan ◽  
Isha Bansal ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Conventional Method ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Line Probe Assay ◽  
Molecular Method ◽  
Traditional Drug ◽  
Probe Assay ◽  
Susceptibility Tests ◽  
Mycobacteria Tuberculosis

Rapid susceptibility testing of Mycobacterium tuberculosis strains is imperative for therapy selection but traditional drug susceptibility tests take weeks or are expensive. Classical drug susceptibility (DST) may take up to 2 to 4 months. The line probe assay is a commercially available line-probe assay that rapidly detects Mycobacterium tuberculosis (MTB) complex, as well as the most common mutations associated with rifampicin and isoniazid. In this study we assessed the sensitivity and specificity of the rapid molecular method in comparison with the conventional method.

scholarly journals Susceptibility Testing of Antibiotics That Degrade Faster than the Doubling Time of Slow-Growing Mycobacteria: Ertapenem Sterilizing Effect versus Mycobacterium tuberculosis

2016 ◽  
Vol 60 (5) ◽  
pp. 3193-3195 ◽  
Author(s):  
Shashikant Srivastava ◽  
Sander P. van Rijn ◽  
A. Mireille A. Wessels ◽  
Jan-Willem C. Alffenaar ◽  
Tawanda Gumbo
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Doubling Time ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Content Type ◽  
New Strategy ◽  
Susceptibility Tests ◽  
Slow Growing ◽  
High Mics

ABSTRACTDrug susceptibility tests (DSTs) forMycobacterium tuberculosisrequire at least 7 days of incubation. Drugs that are unstable at 37°C, such as ertapenem, are likely to be degraded before killing or inhibiting slow-growing bacteria. This would alter the MICs of these drugs, including ertapenem, leading to falsely high MICs. Here, we describe a new strategy we developed to perform DSTs and measure MICs for such unstable compounds.

scholarly journals Thin layer agar-based direct phenotypic drug-susceptibility testing on sputum in Eswatini rapidly detects Mycobacterium tuberculosis growth and rifampicin resistance, otherwise missed by WHO endorsed diagnostic tests.

2021 ◽  
Author(s):  
E. Ardizzoni ◽  
E. Ariza ◽  
D. Mulengwa ◽  
Q. Mpala ◽  
R. de La Tour ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Thin Layer ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Field Conditions ◽  
Reference Laboratory ◽  
Solid Media ◽  
Specific Setting ◽  
Lowenstein Jensen

BACKGROUND: Xpert®MTB/RIF rapidly detects resistance to rifampicin (RR), however this test misses the I491F-RR conferring rpoB mutation, common in Southern Africa. In addition, Xpert®MTB/RIF does not distinguish between viable and dead Mycobacterium tuberculosis (MTB). OBJECTIVE: To investigate the ability of thin layer agar (TLA) direct drug-susceptibility testing (DST) to detect MTB and its drug-resistance profiles in field conditions in Eswatini. DESIGN: Consecutive samples were tested in parallel with Xpert®MTB/RIF and TLA for rifampicin (1.0 μg/ml) and ofloxacin (2.0 μg/ml). TLA results were compared at the Reference Laboratory in Antwerp with indirect DST on Löwenstein-Jensen or 7H11 solid media and additional phenotypic and genotypic testing to resolve discordance. RESULTS: TLA showed a positivity rate for MTB detection of 7.1% versus 10.0% for Xpert®MTB/RIF. Of a total of 4547 samples included in the study, 200 isolates were available for comparison to the composite reference. Within a median of 18.4 days, TLA detected RR with 93.0% sensitivity (CI-77.4-98.0) and 99.4% specificity (CI 96.7-99.9), versus 62.5% (CI 42.7-78.8) and 99.3% (CI 96.2-99.9) for Xpert®MTB/RIF. Eight isolates, 28.6% of all RR confirmed isolates, carried the I491F mutation, all detected by TLA. TLA also correctly identified 183 of the 184 ofloxacin-S isolates (99.5% specificity, CI 97.0-99.9). CONCLUSIONS: In field conditions, TLA rapidly detects RR, and in this specific setting contributed to detection of additional RR patients over Xpert®MTB/RIF, mainly but not exclusively due to I491F. TLA also accurately excluded fluoroquinolones resistance.

scholarly journals Comparison of Proportion and Resistance Ratio Methods for Drug Susceptibility Testing of Mycobacterium tuberculosis Isolated from Patients Attending National Tuberculosis Centre, Nepal

2010 ◽  
Vol 5 (1) ◽  
pp. 13-20
Author(s):  
S Acharya ◽  
P Ghimire ◽  
DK Khadka ◽  
S Nepali
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Fluorescence Microscopy ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Resistance Ratio ◽  
National Tuberculosis ◽  
Smear Negative ◽  
Culture Positive ◽  
Good Agreement

Background: Tuberculosis (TB) is among the most serious infectious cause of global morbidity and mortality. Emergence of Multi-drug resistant tuberculosis (MDR-TB) is posing an increased threat to TB control programs. Drug susceptibility testing (DST) of Mycobacterium tuberculosis (M. tuberculosis) isolates is important for tackling such problems. Setting: National Tuberculosis Centre (NTC), Thimi, Bhaktapur, Nepal. Objectives: Comparative evaluation of two in vitro DST methods in determining susceptibility of M. tuberculosis isolates from patients attending NTC, to front-line anti-TB drugs: (Isoniazid-INH, Rifampicin-RFP, Streptomycin-SM, and Ethambutol-EMB). Methodology: This study was conducted from Sep 2006-Jun 2007. A total of 862 sputum samples (diagnosis or follow up cases) collected from patients (type of patients or their categories was not differentiated in this study) attending NTC bacteriology lab for sputum direct smear microscopy were analyzed using fluorescence microscopy. All smear positive samples, smear negative samples requested for culture were cultured. All culture positive samples confirmed as M. tuberculosis by biochemical tests were processed for DST by both proportion (PR) and resistance ratio (RR) methods. Results: Out of 862 sputum samples analyzed, 226 (26.2%) samples were positive for Acid Fast Bacilli (AFB) by fluorescence microscopy. Among 323 samples 226 smear positive samples and 97 smear negative samples requested for culture), 221 (68.4%) were culture positive, 92 (28.5%) were culture negative and 10 (3.1%) were contaminated. Out of 221 isolates of M. tuberculosis, 57.5% were resistant to one or more drugs by the PR method and 56.6% by the RR method. Similarly, MDR isolates were 29.9% and 29% by PR and RR methods respectively. On correlation analysis using Mc Nemar Chi-square test, no significant difference between the two tests were observed (p>0.05). The results showed high agreement between both methods and agreement rates to INH, RFP, SM and EMB were 93.2%, 93.7%, 93.2% and 94.1% respectively. Similarly, the agreement rates between both methods using kappa analysis showed kappa (k) value of 0.86, 0.85, 0.86 and 0.84 for INH, RFP, SM and EMB respectively, which is believed to be good agreement between both methods (k=0.80 to 1.00: Very good agreement). Conclusion: In conclusion, this study showed that both the Proportion and Resistance ratio methods are equally good for determining drug susceptibility of M. tuberculosis. Keywords: Mycobacterium tuberculosis; Drug Susceptibility Testing; Proportion Method; Resistance Ratio Method. DOI: 10.3126/saarctb.v5i1.3078 SAARC J. Tuber. Lung Dis. HIV/AIDS 2008 Vol.5(1) 13-20

scholarly journals Comparison of the Performances of Two In-House Rapid Methods for Antitubercular Drug Susceptibility Testing

2008 ◽  
Vol 53 (2) ◽  
pp. 808-810 ◽  
Author(s):  
Agustina I. de la Iglesia ◽  
Emma J. Stella ◽  
Héctor R. Morbidoni
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Sensitivity And Specificity ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Antitubercular Drug ◽  
Rapid Methods ◽  
Resistance Assessment

ABSTRACT Resistance to rifampin (rifampicin), isoniazid, and streptomycin of 69 Mycobacterium tuberculosis isolates was analyzed by an in-house method based on mycobacteriophage D29 and a colorimetric micromethod. Both methods showed sensitivity and specificity values ranging from 93% to 100%. These simple methods offer an option for drug resistance assessment of M. tuberculosis.

Assessment of Laboratory Performance With Streptococcus pneumoniae Antimicrobial Susceptibility Testing in the United States

1999 ◽  
Vol 123 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Gary V. Doern ◽  
Angela B. Brueggemann ◽  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
The United States ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Susceptibility Tests

Abstract Objective.—To assess the performance of clinical microbiology laboratories in the United States when conducting in vitro susceptibility tests with Streptococcus pneumoniae. Methods.—The results of a nationwide College of American Pathologists Proficiency Survey test sample, in which susceptibility testing of an isolate of S pneumoniae was performed, were assessed with respect to precision and accuracy. Results.—Wide variability was noted among participating laboratories with both minimum inhibitory concentration procedures and disk diffusion susceptibility tests when both methods were applied to S pneumoniae. Despite this high degree of variation, categorical interpretive errors were uncommon. Numerous laboratories reported results for antimicrobial agents that are not recommended by the National Committee for Clinical Laboratory Standards for tests with S pneumoniae. Conclusions.—Current susceptibility testing practices with S pneumoniae in the United States indicate limited precision and a tendency for laboratories to test and report results obtained with antimicrobial agents of questionable therapeutic value against this organism. Continued efforts to standardize susceptibility testing of S pneumoniae in the United States are warranted. In addition, modifications of existing interpretive criteria may be necessary.

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