NEQAS

1. National External Quality Assessment Scheme (NEQAS) for antimicrobial susceptibility testingDerek BrownClinical Microbiology and Public Health Laboratory (CMPHL), Addenbrooke’s Hospital, Cambridge UK NEQAS

2. External Quality Assessment (EQA) • What is EQA? • (UK) NEQAS • The NEQAS process for susceptibility testing • Problem areas

3. External Quality Assessment The challenge of laboratory procedures with specimens of known but undisclosed content

4. Quality Assurance in the clinical diagnostic laboratory The total process by which the quality of laboratory reports can be guaranteed

5. Components of quality assurance Standardisation Evaluation Validation Audit Quality Assurance Education Accreditation Internal Quality Assessment (specimen reprocessing) External Quality Assessment Routine quality control

6. Participants in the NEQAS Microbiology Schemes (n=1658)

7. Anti-HBs serology Hepatitis B serology Hepatitis C serology HIV serology HIV RNA quantification HCV RNA detection Virus Identification Immunity screen (HAV, CMV, VZV) Rubella IgG serology Diagnostic serology (HAV IgM, CMV IgM, EBV; Rubella IgM, Erythrovirus IgM, Streptococcal Abs.) Antimicrobial assay Faecal parasitology Blood parasitology Toxoplasma IgG Toxoplasma IgM Parasitology teaching General bacteriology Antimicrobial susceptibility testing AAFB microscopy Mycobacterium culture Syphilis serology Mycology Chlamydia detection HBV DNA quantification* Mol. Detection of Viruses in CSF* NEQAS Microbiology schemes(CPA Accredited)

8. Participants in NEQAS susceptibility testing (2005 S. pneumoniae 7573 with penicillin) Arab Emirates 2 Austria 43 Belgium 4 Croatia 3 Denmark 16 Finland 24 Germany 2 Gibraltar 1 Gambia 1 Greece 11 Hong Kong 1 Iceland 1 Ireland 41 Israel 12 Italy 111 Norway 6 Netherlands 19 Portugal 54 Romania 28 Slovenia 1 Sweden 26 Switzerland 22 Turkey 6 United Kingdom 286 Zambia 5 Total 726

9. SUMMARY Antimicrobial Susceptibility Testing • Started 1971 as part of the General Bacteriology Scheme • Introduced a dedicated Antimicrobial Susceptibility Testing Scheme in April 2004 • Increased specimen numbers to 24 / year • Wider panel of antimicrobials included • Organism speciation requested • Analysis of results for different methods / guidelines • Feedback reports include more frequent expert comment • New scoring scheme

10. Benefits of EQA in antimicrobial susceptibility testing • Independent assessment of performance • Assessment of performance over time • Comparison with other laboratories • Performance indicator for accreditation • Highlights problem areas • Performance related to methodology • International differences highlighted

11. “Limitations” of EQA in antimicrobial susceptibility testing • Number of specimens distributed is small • May be considered inappropriate to send some organisms • Specimens do not reflect routine isolates • Laboratories may not treat specimens as routine

12. The EQA process Organising laboratory Participants Prepare EQA Samples Examine samples Analyse results Report results Prepare report Evaluate

13. SUMMARY Prepare EQA Samples • AST Advisory Group advises on organisms/ resistances and agents for reference tests • Reference laboratory 1 collects appropriate organisms and tests MICs by BSAC and CLSI methods (and other tests as appropriate) • Selected organisms tested by Reference Laboratory 2 • Organisms with close agreement in MICs between reference laboratories selected for distribution and sent to Quality Assurance Laboratory (QAL) • QAL retest organisms before and after freeze drying • Any anomalies investigated by reference Laboratory 1 • Selected organisms scheduled for distribution to participants

14. SUMMARY Examine samples Report results • Examine NEQAS specimens as if they were routine specimens • Report results as they would be routinely reported

15. SUMMARY Prepare report Analyse results • Analyse results and prepare Report to format agreed by the AST Advisory Group • In consultation with reference laboratories and other experts as appropriate • Distribute report to participants

16. Interpreting NEQAS reports on Antimicrobial Susceptibility Testing

17. Distribution number Laboratory number Date of distribution Page heading

18. Organism identification Intended susceptibility results based on MIC determination in two reference laboratories by the BSAC method and breakpoints Unique specimen numbers for the organisms Intended Results

19. Identification and susceptibility results reported by you Intended Results

20. Identification and susceptibility results reported by you Your score for each agent tested Intended Results

21. Identification and susceptibility results reported by you Results not scored if discrepancy rates high or BSAC and CLSI (NCCLS) interpretations differ Your score for each agent tested Intended Results

22. Scoring of NEQAS susceptibility results

23. Cumulative score information Gives participants an indication of how they are performing in comparison with other participants in the scheme

24. Cumulative score information Gives participants an indication of how they are performing in comparison with other participants in the scheme Specimens numbers of organisms included in the analysis

25. Cumulative score information Gives participants an indication of how they are performing in comparison with other participants in the scheme Specimens numbers of organisms included in the analysis Your cumulative score Sum of scores for all agents you tested against the organisms

26. Cumulative score information Gives participants an indication of how they are performing in comparison with other participants in the scheme Specimens numbers of organisms included in the analysis Your cumulative score Sum of scores for all agents you tested against the organisms Mean cumulative score Mean sum of scores and standard error for all agents you tested against the organisms

27. Cumulative score information Gives participants an indication of how they are performing in comparison with other participants in the scheme Specimens numbers of organisms included in the analysis Your cumulative score Sum of scores for all agents you tested against the organisms Mean cumulative score Mean sum of scores and standard error for all agents you tested against the organisms Your performance rating The number of standard errors by which your cumulative score is above or below the mean. A negative standard error indicates performance below the mean. A negative standard error greater than 1.96 can indicate significantly poor performance

28. Comments Comments related to the organisms in this distribution

29. Comments Comments related to the organisms in this distribution General comments related to analysis of all distributions

30. Comments Comments related to the organisms in this distribution General comments related to analysis of all distributions Contact information for obtaining repeat specimens and technical enquiries Note that digital images of disc diffusion results by the BSAC method are on the NEQAS website www.ukneqas.org.uk

31. List of agents tested in the reference labs Organism identification MICs and interpretations by the BSAC method MICs and interpretations by the CLSI (NCCLS) method Reference laboratory results

32. Analysis of participants’ results Detailed breakdown of results for each agent and each organism

33. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Intended result with this agent

34. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Intended result with this agent Number of labs following specific susceptibility testing guidelines

35. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Intended result with this agent Number of labs following specific susceptibility testing guidelines MIC breakpoints for specific susceptibility testing guidelines

36. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Result in labs using the same guidelines and method as you Mode and range of zone diameters and MICs Intended result with this agent Number of labs following specific susceptibility testing guidelines MIC breakpoints for specific susceptibility testing guidelines

37. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Result in labs using the same guidelines and method as you Mode and range of zone diameters and MICs Results with different susceptibility testing guidelines Percent concordance with reference result by BSAC method Intended result with this agent Number of labs following specific susceptibility testing guidelines MIC breakpoints for specific susceptibility testing guidelines

38. Analysis of participants’ results Detailed breakdown of results for each agent and each organism Result in labs using the same guidelines and method as you Mode and range of zone diameters and MICs Results with different susceptibility testing guidelines Percent concordance with reference result by BSAC method Intended result with this agent Number of labs following specific susceptibility testing guidelines MIC breakpoints for specific susceptibility testing guidelines Results for all labs/UK labs combined

39. Evaluate • Review the results with all staff (include successes and failures) • Investigate problems • How many other participants failed with the specimen? • Are there any relevant comments? • Technical or interpretive issues? • Keep records of your reviews and the reasons for any decisions made

40. Problem areas in susceptibility testingDiscrepancies in UK NEQAS reports forS. aureus, April 1995-March 2004

41. Reliability of detection of methicillin/ oxacillin resistance in S aureus in NEQAS specimens in the UK Heterogeneous β-lactamase -ve Salt intolerant 2005 1980

42. Methicillin/oxacillin zones with MRSA

43. Detection of oxacillin resistance in EARSS and NEQAS specimens with mecA positive S aureus

44. Zone diameters with cefoxitin 10g for S. aureus by BSAC method at 35oC (Andrews et al, 2005)

45. Reporting penicillinase-hyperproducersS aureus 7876, Dist 2020Oxacillin MIC 0.5-1 mg/L, mecA-ve, Susceptible

46. NEQAS reports for glycopeptide I/R staphS. epidermidis 7156, Dist. 1799Teicoplanin MIC 8-16 mg/L, I/R

47. Glycopeptide susceptibility testing of staphylococci • Disc diffusion methods are unreliable • BSAC recommends an MIC method for teicoplanin susceptibility testing of CNS • GISA indicated by treatment failure • BHI +6 mg/L vancomycin (0.5 McFarland inoculum) or 5mg/L teicoplanin (2 McFarland inoculum) for screening for GISA. Confirm by MIC • Significance of hGISA unclear • Etest macromethod for screening for hGISA • Confirm by population analysis profile (reference laboratory)

48. Differences in breakpoints may affect reporting S aureus 7240, Ciprofloxacin, Dist 1821(MIC 0.5 mg/L) S aureus 7876, Ciprofloxacin, Dist 2020 (MIC 0.25 mg/L) EUCAST breakpoints S<1 R>1 mg/L

49. Error rates for S. pneumoniae with reduced susceptibility to penicillin are related to MIC (S <0.06, I 0.12-1, R >1 mg/L)

50. S. pneumoniae penicillin interpretation depends on the site of the infectionS. pneumoniae 7346, Dist. 1848 penicillin MIC 0.5 mg/L, Intermediate in vitro (clinically resistant from meningitis)