BEIPH Report. QCMD 2010 Mycobacterium tuberculosis DNA (MTBDNA10) EQA Programme

Transcription

1 QUALITY CONTROL for MOLECULAR DIAGNOSTICS The Altum Building, Todd Campus, West of Scotland Science Park, Glasgow, G20 0XA Scotland Tel: +44 (0) Fax: +44 (0) BEIPH Report QCMD 2010 Mycobacterium tuberculosis DNA (MTBDNA10) EQA Programme William G MacKay on behalf of QCMD and its Scientific Council October 2010 Not to be reproduced or quoted without permission of QCMD. Any queries about this report should be addressed to the QCMD Neutral Office. The QCMD programme is organised in collaboration with the European Society for Clinical Virology and the European Society for Clinical Microbiology & Infectious Diseases. Registered in Scotland Reg No: SC Registered Office: 7 Castle Street, Edinburgh EH2 3AH

2 1. Programme aims The primary aim of this External Quality Assessment Programme was to assess the proficiency of laboratories in the detection of Mycobacterium tuberculosis complex. 2. Programme details Table 1: Programme details MTBDNA10 Date of panel distribution 09/08/2010 Number of respondents 18 (90%) Number of participants 20 Number of datasets submitted 18 Number of countries 1 Number of qualitative datasets submitted 18 (100%) Number of qualitative and quantitative datasets submitted 0 (0%) Two participants did not return results. One of these withdrew officially, citing 'assay not offered' as the reason. 3. Panel composition This EQA panel for the detection of Mycobacterium tuberculosis (M. tuberculosis ) complex consisted of eight samples containing various concentrations of Mycobacterium bovis (M. bovis ) BCG and two samples negative for M. bovis BCG. Simulated clinical samples were included: half of the panel consisted of sputum; the other half of a protein rich buffer to simulate cerebrospinal fluid (CSF). Samples contained M. bovis BCG, which belongs to the M. tuberculosis complex, and are considered to be nonpathogenic. The QCMD EQA panels contain a range of samples, designed to look at different aspects of assay performance. Panel members are designated core proficiency samples on the basis of scientific information, clinical relevance and clinical experience (published literature and professional clinical guidelines) and, where available and appropriate, established target performance limits taken from previous QCMD EQA distributions. Laboratories are expected to correctly analyse and report the core proficiency samples in order to show acceptable proficiency. Table 2: Panel composition Sample Sample Sample * Sample conc. Sample Sample content matrix (Cells/vial ) status type 250µL MTB10-01 M. tuberculosis complex PRB 10,000 Frequently detected Core MTB10-05 M. tuberculosis complex PRB 500 Detected Core MTB10-03 M. tuberculosis complex PRB 500 Detected Core MTB10-04 M. tuberculosis complex PRB 100 Detected MTB10-02 Mtb Negative PRB Negative Core MTB10-07 M. tuberculosis complex Sputum 10,000 Frequently detected Core MTB10-06 M. tuberculosis complex Sputum 500 Detected Core MTB10-10 M. tuberculosis complex Sputum 500 Detected Core MTB10-08 M. tuberculosis complex Sputum 100 Infrequently detected MTB10-09 Mtb Negative Sputum Negative Core Key to Table 2 Sample: QCMD panel sample codes for the samples distributed to participants. Sample content: microbial content of the panel samples. Sample matrix: material used as a matrix in preparation of the panel samples. Sample conc.: predefined specifications for QCMD internal purposes only. Values should not be used by participants for method comparison or as a target for individual laboratory performance assessment. Sample status: the sample status assigned to each panel sample consisting of 'Frequently detected', 'Detected', 'Infrequently detected' or 'Negative'. Please see Appendix A for more information. Sample type: panel samples classified as core proficiency samples. * PRB: Protein Rich Buffer (0.1% Tween 20, 0.5% Bovine serum albumin in phosphate buffered saline to simulate cerebrospinal fluid). Sputum: Pooled sputum negative for Mtb complex. PAGE 2 of 6

3 4. Programme results 4.1. Qualitative performance on the core proficiency samples Figure 1 shows the performance of participants on the core proficiency samples. In this round of the EQA 72.2% of datasets returned to QCMD by BEIPH participants reported all core proficiency samples correctly. Figure 1: Performance on the core proficiency samples for BEIPH participants Percentage of datasets 100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 72.2% 16.7% 5.6% 5.6% 4.2. Qualitative analysis of the EQA data for all panel samples 0.0% 0.0% 0.0% 0.0% 0.0% 8/8 7/8 6/8 5/8 4/8 3/8 2/8 1/8 0/8 Number of core samples correct The number (percentage) of correct qualitative results are presented in Table 3. Qualitative data were returned by participants as 'positive', 'negative' or 'not determined'. Not determined results were counted as incorrect for all panel samples (positive or negative). QCMD organises datasets according to commercial and in-house technology groups, which are Conventional PCR, Real time PCR, NASBA, SDA, TMA and bdna. Where datasets were reported as other for a technology or kit method this was reviewed by the QCMD Neutral Office and assigned to an appropriate group where possible. Table 3: Number of correct qualitative results per panel member and technology type Sample Sample Sample conc. Key to Table 3 Sample: QCMD panel sample codes for the samples distributed to participants. Sample content: microbial content of the panel samples. Sample conc.: predefined specifications for QCMD internal purposes only. Values should not be used by participants for method comparison or as a target for individual laboratory performance assessment. Total datasets: number and percentage of datasets reporting the correct qualitative result for each panel sample. A breakdown of the results for all datasets is also provided based on technology type. a: Roche COBAS Amplicor MTB (n=3). b: Details not presented. c: Cepheid Xpert MTB/RIF (n=4), PathoFinder RealAccurate MTB kit (n=2), QIAGEN artus M. tuberculosis PCR Kit (RG) (n=1), Roche COBAS TaqMan MTB Test (n=2). d: Details not presented. content f: Becton Dickinson ProbeTec ET (n=1). (Cells/vial*) *250µL Total Conventional Real time datasets Commercial a In-house b Commercial c In-house d n % n % n % n % n % n % MTB10-01 M. tuberculosis complex 10, MTB10-05 M. tuberculosis complex MTB10-03 M. tuberculosis complex MTB10-04 M. tuberculosis complex MTB10-02 Mtb Negative MTB10-07 M. tuberculosis complex 10, MTB10-06 M. tuberculosis complex MTB10-10 M. tuberculosis complex MTB10-08 M. tuberculosis complex MTB10-09 Mtb Negative PCR SDA f n=18 n=3 n=1 n=9 n=4 n=1 PAGE 3 of 6

4 4.3. Qualitative performance scores for all panel samples Table 4: Qualitative performance scores per technology type Sample Key to Table 4 Sample: QCMD panel sample codes for the samples distributed to participants. Sample status: the sample status assigned to each panel sample. Please see Appendix A for more information. Total. All technologies: number of datasets awarded each score (0 to 3). A breakdown of the results for all datasets is also provided based on technology type. These data are presented graphically in Figure 2. a: Roche COBAS Amplicor MTB (n=3). b: Details not presented. c: Cepheid Xpert MTB/RIF (n=4), PathoFinder RealAccurate MTB kit (n=2), QIAGEN artus M. tuberculosis PCR Kit (RG) (n=1), Roche COBAS TaqMan MTB Test (n=2). d: Details not presented. Sample Status f: Becton Dickinson ProbeTec ET (n=1). Total All technologies n=18 Conventional Commercial a In-house b Real time Commercial c In-house d n=3 n=1 n=9 n= MTB10-01 Frequently detected MTB10-05 Detected MTB10-03 Detected MTB10-04 Detected MTB10-02 Negative MTB10-07 Frequently detected MTB10-06 Detected MTB10-10 Detected MTB10-08 Infrequently detected MTB10-09 Negative PCR SDA f n=1 Figure 2: Percentage of qualitative performance scores per technology type % a b c d f a b c d f a b c d f a b c d f a b c d f a b c d f a b c d f a b c d f a b c d f a b c d f MTB10-01 MTB10-05 MTB10-03 MTB10-04 MTB10-02 MTB10-07 MTB10-06 MTB10-10 MTB10-08 MTB10-09 Technology group per panel sample a: Conventional commercial PCR, b: Conventional in-house PCR, c: Real time commercial PCR, d: Real time in-house PCR, f: SDA. PAGE 4 of 6

5 4.4. Qualitative analysis of the EQA data by assay target gene Participants were asked to specify the target gene of their assay when submitting their results. All datasets returned to QCMD by BEIPH participants contained information on the target gene. These data are summarised in Table 5. Table 5: Analysis of the qualitative data by assay target gene Sample Sample Sample conc. content Copies/vial Total datasets 16S rdna IS6110 rpob 16S - 32S rdna n=18 n=7 n=6 n=4 n=1 n % n % n % n % n % MTB10-01 M. tuberculosis complex 10, MTB10-05 M. tuberculosis complex MTB10-03 M. tuberculosis complex MTB10-04 M. tuberculosis complex MTB10-02 Mtb Negative MTB10-07 M. tuberculosis complex 10, MTB10-06 M. tuberculosis complex MTB10-10 M. tuberculosis complex MTB10-08 M. tuberculosis complex MTB10-09 Mtb Negative Key to Table 5 Sample: QCMD panel sample codes for the samples distributed to participants. Sample content: microbial content of the panel samples. Sample conc.: predefined specifications for QCMD internal purposes only. Values should not be used by participants for method comparison or as a target for individual laboratory performance assessment. Total datasets: number and percentage of datasets reporting the correct qualitative result for each panel sample. A breakdown of the results for all datasets is also provided based on target gene. Acknowledgements Data analysis and report generation were performed by Stuart West and William MacKay of the QCMD Neutral Office. QCMD The QCMD EQA programme samples, associated reports and data generated during this programme are intended for External Quality Assessment (EQA) and Proficiency Testing (PT) purposes only. QCMD operates according to a strict Code of Practice which is in line with ISO/IEC and associated standards. Data reported in QCMD programmes is representative of a laboratory s standard diagnostic testing protocols irrespective of the technology they use. The data provided in the reports are based on technical information provided by the individual laboratories as part of the assessment process, as such it does not constitute a formal technology method comparison. All text and images produced by QCMD are the property of QCMD unless otherwise stated. The reproduction and use of these materials is not permitted without the express written consent of QCMD. The use of the information provided in QCMD reports for commercial purposes is strictly prohibited. PAGE 5 of 6

6 Appendix A Assigning the sample status Sample status is assigned by peer-group consensus, based on the qualitative results returned by all participants in the full EQA programme. It is not a measure of the 'strength' of a positive sample nor is it technology-dependent, and is used solely for the scoring of the EQA data. The rationale for the sample status is: Frequently detected: More than 95% of datasets recorded the correct positive result. Detected: Between 65% and 95% of datasets recorded the correct positive result. Infrequently detected: Less than 65% of datasets recorded the correct positive result. Negative: A panel sample that does not contain the target and produces an unequivocal negative result. Scoring system for qualitative EQA data The scores awarded for qualitative EQA data were based on the sample status. The scoring system is represented in the following table, where 0 is 'highly satisfactory' and 3 is 'highly unsatisfactory'. Colour has been included as an extra visual aid. Scoring system based on the assigned sample status Sample status Participant's result Negative Not determined Positive Frequently detected Detected Infrequently detected Negative PAGE 6 of 6