BEIPH Final Report. QCMD 2009 Neisseria gonorrhoeae (NGDNA09) EQA Programme

Transcription

1 QUALITY CONTROL for MOLECULAR DIAGNOSTICS Block 4, Kelvin Campus, West of Scotland Science Park, Glasgow, G20 0SP Scotland Tel: +44 (0) Fax: +44 (0) BEIPH Final Report QCMD 2009 Neisseria gonorrhoeae (NGDNA09) EQA Programme William G MacKay on behalf of QCMD and its Scientific Advisory Board September 2009 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 aims of this External Quality Assessment Programme were: 1) To determine the qualitative performance of participants testing for Neisseria gonorrhoeae using molecular technologies. 2) To determine the incidence of false positive results and to compare performance with the previous distribution. 3) Determine the performance of Neisseria gonorrhoeae tests in samples containing low concentrations of Neisseria gonorrhoeae and high concentrations of Chlamydia trachomatis. 2. Programme details Table 1: Programme details NgDNA09 Date of panel distribution 15/06/2009 Number of participants 30 Number of countries 1 Number of respondents 29 (97%) Number of datasets submitted 29 Number of qualitative datasets submitted 29 (100%) Number of qualitative and quantitative datasets submitted 0 (0%) One participant withdrew officially, citing 'assay under development' as the reason. 3. Panel composition This EQA panel for the detection of Neisseria gonorrhoeae consisted of eight samples containing various concentrations of N. gonorrhoeae and two samples negative for N. gonorrhoeae, one of which contained N. lactamica. All panel materials were subjected to independent testing by laboratories recognised as expert in the detection of these targets. Table 2: Panel composition Sample Sample * Sample Sample conc. Sample content matrix status NG09-01 N. gonorrhoeae (pool G) Urine 4.0 x10-4 Diln Infrequently detected NG09-02 N. gonorrhoeae (pool G) Urine 1.0 x10-3 Diln Detected NG09-03 N. gonorrhoeae (pool F) Urine 1.7 x10-3 Diln Detected NG09-04 N. gonorrhoeae (St 49226) Urine 1.0x10 3 CFU/ml Detected NG09-05 N. gonorrhoeae Negative Urine Negative NG09-06 N. gonorrhoeae (St 49226) Urine 1.0x10 5 CFU/ml Frequently detected NG09-07 N. gonorrhoeae (pool G) Urine 1.0 x10-3 Diln Detected NG09-08 N. lactamica (SB3285) Urine 1.0x10 5 CFU/ml Negative NG09-09 N. gonorrhoeae (pool G) Urine 1.0 x10-2 Diln Frequently detected NG09-10 N. gonorrhoeae (pool G) Urine 4.0 x10-4 Diln Infrequently detected Key to Table 2 Sample: QCMD panel sample codes for the samples distributed to participants. Sample content: viral or 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. Diln: Dilution factor. 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. * Stocks of pool G and pool F were mixtures of Neisseria gonorrhoeae postive clinical urine samples. Neisseria gonorrhoeae strain St and Neisseria lactamica strain SB3285 were obtained from Helen Palmer, Bristol, U.K. (J. Clin. Microbiol. 41 (2003) ). Human urine collected from healthy adult volunteers negative for N. gonorrhoeae. : N. gonorrhoeae (Pool F) does not contain the cryptic plasmid cppb and has been shown to produce false negative results in protocols targeting cppb. : Panel sample NG09-10 also contained a 4.0 x 10-4 stock dilution of C. trachomatis. This C. trachomatis dilution has been assigned a 'frequently detected' status in previous QCMD Chlamydia trachomatis programmes. PAGE 2 of 6

3 4. Programme results As the primary objective of the QCMD N. gonorrhoeae DNA EQA programme is to assess the reporting of results in the clinical context participants were asked to report their final clinical results. Where participants reported performing a confirmatory test these results were included in the analysis presented in the following tables. Out of the 29 datasets reported to QCMD three included data on confirmatory testing. 4a. Qualitative analysis of the EQA data 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. content d Total Conventional Real time datasets Commercial a Commercial c In-house n=29 n=9 n=2 n=8 n=9 n=1 n % n % n % n % n % n % NG09-06 N. gonorrhoeae (St 49226) 1.0x10 5 CFU/ml NG09-04 N. gonorrhoeae (St 49226) 1.0x10 3 CFU/ml NG09-03 N. gonorrhoeae (pool F) 1.7 x10-3 Diln NG09-09 N. gonorrhoeae (pool G) 1.0 x10-2 Diln NG09-07 N. gonorrhoeae (pool G) 1.0 x10-3 Diln NG09-02 N. gonorrhoeae (pool G) 1.0 x10-3 Diln NG09-01 N. gonorrhoeae (pool G) 4.0 x10-4 Diln NG09-10 N. gonorrhoeae (pool G) 4.0 x10-4 Diln NG09-08 N. lactamica (SB3285) 1.0x10 5 CFU/ml NG09-05 N. gonorrhoeae Negative Key to Table 3 Sample: QCMD panel sample codes for the samples distributed to participants. Sample content: viral or 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. Diln: Dilution factor. 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. PCR SDA f TMA g : N. gonorrhoeae (Pool F) does not contain the cryptic plasmid cppb and has been shown to produce false negative results in protocols targeting cppb. : Panel sample NG09-10 also contained a 4.0 x 10-4 stock dilution of C. trachomatis. This C. trachomatis dilution has been assigned a 'frequently detected' status in previous QCMD Chlamydia trachomatis programmes. a: Roche Amplicor CT/NG (n=2), Roche Amplicor CT/NG, confirmation details not provided (n=1), Roche Amplicor CT/NG, confirmation using In-house Real time PCR (n=2), Roche COBAS Amplicor CT/NG (n=4). c: Abbott Real time CT/NG (n=2). d: Details not presented. f: Becton Dickinson ProbeTec CT/NG (n=9). g: Gen-Probe Aptima Combo 2 (n=1). PAGE 3 of 6

4 4b. Qualitative performance scores Table 4: Qualitative performance scores per technology type Total PCR SDA f TMA g Sample Sample All technologies Conventional Real time Status Commercial a Commercial c In-house d n=29 n=9 n=2 n=8 n=9 n= NG09-06 Frequently detected NG09-04 Detected NG09-03 Detected NG09-09 Frequently detected NG09-07 Detected NG09-02 Detected NG09-01 Infrequently detected NG09-10 Infrequently detected NG09-08 Negative NG09-05 Negative 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 1. a: Roche Amplicor CT/NG (n=2), Roche Amplicor CT/NG, confirmation details not provided (n=1), Roche Amplicor CT/NG, confirmation using In-house Real time PCR (n=2), Roche COBAS Amplicor CT/NG (n=4). c: Abbott Real time CT/NG (n=2). d: Details not presented. f: Becton Dickinson ProbeTec CT/NG (n=9). g: Gen-Probe Aptima Combo 2 (n=1). Figure 1: Percentage of qualitative performance scores per technology type % a c d f g a c d f g a c d f g a c d f g a c d f g a c d f g a c d f g a c d f g a c d f g a c d f g NG09-06 NG09-04 NG09-03 NG09-09 NG09-07 NG09-02 NG09-01 NG09-10 NG09-08 NG09-05 Technology group per panel sample a: Conventional commercial PCR, c: Real time commercial PCR, d: Real time in-house PCR, f: SDA, g: TMA. PAGE 4 of 6

5 Acknowledgements This will be the last N. gonorrhoeae EQA programme with Jurjen Schirm as the scientific expert. Jurjen retires this year after a highly successful career as an infectious disease scientist. We thank Jurjen for all of his hard work and support of QCMD and wish him the very best for the future. QCMD would like to thank Dora Adema and Joke Sipma (Laboratory of Infectious Diseases, Groningen) for preparation of the samples and for in-process testing. Data analysis and report generation were performed by 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 guide 43-1 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 constituent 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. 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 rational 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 (see Section 3). 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