1. ANALYTICAL PROCESS CONTROL
QC for QUALITATIVE TESTS
John Elliot
PPTC, Wellington, NZ
WHO Collaborating Centre

2. Laboratory Sections that use Qualitative Tests
Microbiology
Blood Transfusion
Infectious Diseases Serology
PPTC, Wellington, NZ

3. INTERNAL QUALITY CONTROL (IQC)
IQC REFERS TO THE SET OF PROCEDURES UNDERTAKEN BY THE LABORATORY STAFF FOR THE
CONTINUOUS AND IMMEDIATE
MONITORING OF LABORATORY WORK IN ORDER TO DECIDE WHETHER THE RESULTS ARE RELIABLE ENOUGH TO BE RELEASED.
PPTC, Wellington, NZ

4. What is IQC? But does this apply to qualitative tests?
The regular testing of quality control [QC] material along with the patient samples
Comparison of the QC results to specific statistical limits [ranges]
Rejection of patient results if QC is outside of limits
But does this apply to qualitative tests?
If not, Why not?
PPTC, Wellington, NZ

5. WHAT IS THE MOST COMMON LABORATORY ERROR?
TRANSCRIPTION
Not technical
PPTC, Wellington, NZ

6. Microbiology Quality Control
Accuracy and clinical value of results depend on:
Quality of specimen
Validity of test method
Performance of test procedure, reagents and media
Reports and interpretation
Staff
Equipment
PPTC, Wellington, NZ

7. In Microbiology how do we QC
The Quality of the specimen
The Performance of test procedures, reagents and media
PPTC, Wellington, NZ

8. Specimen Appropriate specimen Collection method Delivery system
PPTC, Wellington, NZ

9. Gram Stain
PPTC, Wellington, NZ

10. PPTC, Wellington, NZ

11. PPTC, Wellington, NZ

12. IDENTIFICATION SYSTEM
PPTC, Wellington, NZ

13. Specimen Processing: Test Methods
Staining and Microscopy
Culture Media
Incubation
Organism Identification
Antimicrobial Susceptibility Testing
PPTC, Wellington, NZ

14. Culture Media: Both Solid and Liquid
Dating when received and when opened
Weighing
Dissolving
Sterilizing
Storage of prepared media
Addition of enrichments [eg Blood]
Sterility Testing
Incubation of inoculated media
PPTC, Wellington, NZ

15. QC of Media Agar Plates Liquid broths Therefore Stock Cultures
Haemolysis controls
Selective media controls
Liquid broths
Positive and negative reactions
Therefore Stock Cultures
PPTC, Wellington, NZ

16. Stock QC organisms
Organisms to be maintained must be adequate to check all media and test systems.
E. coli – MacConkey, XLD, susceptibility tests
Staphylococcus aureus – Blood agar, Mannitol Salt, susceptibility tests
Neisseria gonorrhoeae – chocolate, Thayer-Martin
Discussion of where to get control organisms
Discuss media used in their labs and what organisms should be used to test it.
ATCC – best, but other sources may be available.
May use known organisms from their lab and make stock cultures??
PPTC, Wellington, NZ

17. QC of Stains and Reagents
Gram stain QC
Use gram positive and gram negative organisms to check regularly [at least once a week]
ZN QC
Use positive and negative AFB slide with every batch stained.
Other Stains
Check as used – positive and negative reactions
Reagents
Check as used with known positives and negatives.
PPTC, Wellington, NZ

18. Temperature Chart:Incubator
PPTC, Wellington, NZ

19. Temperature Chart: Refrigerator
PPTC, Wellington, NZ

20. Antimicrobial Susceptibility Testing
Storage of antibiotic disks
Correct concentration of antibiotic in disk
Joan Stokes Method
NCCLS Method
Detailed QC Procedures to ensure reproducability of results
Depth of agar!!
PPTC, Wellington, NZ

21. Antimicrobial Susceptibility Testing
PPTC, Wellington, NZ

22. Detecting Errors
Many organisms have predictable antimicrobial test results
Staphylococcus spp. are usually susceptible to vancomycin
Streptococcus pyogenes are always susceptible to penicillin
Klebsiella pneumoniae are resistant to ampicillin
I think you could include a pretty long list here, that are worldwide in application.
PPTC, Wellington, NZ

23. Sources of Error If you encounter an unusual pattern
rule out error by checking identification of organisms
repeat antimicrobial susceptibility test
Report if repeat testing yields same result, or refer the isolate to a reference laboratory for confirmation
Establish patterns in your patient population and advise health care providers.
So providers can initiate treatment if necessary before susceptibility testing is complete
PPTC, Wellington, NZ

24. QC in Blood Transfusion Service
PPTC, Wellington, NZ

25. Blood Transfusion Service
Blood Bank
Hospital ?
Donors
Recipients
Safety Precautions
Recruit – Screen – Bleed test – process – Xmatch transfuse – follow up
Policies
Regulation
FUNDING
Government
PPTC, Wellington, NZ

26. QC in Blood Bank Technology
Donor services
Blood grouping
Crossmatch & antibody screening
Transfusion
PPTC, Wellington, NZ

27. QC in Blood Bank Positive and negative controls on all tests
Reverse grouping
Good documentation, SOPs etc
Equipment monitoring, calibration, maintenance
PPTC, Wellington, NZ

28. QC of Rapid Tests for Infectious Diseases
PPTC, Wellington, NZ

29. Infectious Diseases Serology QC of Rapid Methods
IQC
Positive controls
Negative controls
How often?
Where do you get the controls from?
PPTC, Wellington, NZ

30. PPTC, Wellington, NZ

31. Qualitative vs.Quantitative
Quantitative test
measures the amount of a substance present
Qualitative test
determines whether the substance being tested for is present or absent
Qualitative tests
Tests that do not have measurable endpoints, for example:
Growth-no growth
Positive-negative
Color change
PPTC, Wellington, NZ

32. What is Quality Control?
Process or system for monitoring the quality of laboratory testing, and the accuracy and precision of results
Routinely collect and analyze data from every test run or procedure
Allows for immediate corrective action
PPTC, Wellington, NZ

33. Designing a QC Program –
Establish written policies and procedures
Corrective action procedures
Train all staff
Design forms
Assure complete documentation and review
PPTC, Wellington, NZ