# Presentation: 192514

## ANALYTICAL PROCESS CONTROL

**QC for QUALITATIVE TESTS**
**John Elliot**

- WHO Collaborating Centre

- PPTC, Wellington, NZ

## Laboratory Sectionsthat useQualitative Tests

- Microbiology
- Blood Transfusion
- Infectious Diseases Serology

- PPTC, Wellington, NZ

## 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

## What is IQC? 

- 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

## WHAT IS THE MOST COMMON LABORATORY ERROR?

***WHAT IS THE MOST COMMON LABORATORY ERROR?***

- 		   **TRANSCRIPTION**
- 		**Not technical**

- PPTC, Wellington, NZ

## 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

##  In Microbiology how do we QC

- The Quality of the specimen
- The Performance of test procedures, reagents and media

- PPTC, Wellington, NZ

## Specimen

- Appropriate specimen
- Collection method
- Delivery system

- PPTC, Wellington, NZ

## Gram Stain

**Gram Stain**

- PPTC, Wellington, NZ

## Slide 10

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## Slide 11

- PPTC, Wellington, NZ

## IDENTIFICATION SYSTEM

_*IDENTIFICATION SYSTEM*_

- PPTC, Wellington, NZ

## Specimen Processing:		Test Methods

- Staining and Microscopy
- Culture Media
- Incubation
- Organism Identification
- Antimicrobial Susceptibility Testing

- PPTC, Wellington, NZ

## 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

## QC of Media

- Agar Plates
- Haemolysis controls
- Selective media controls
- Liquid broths
- Positive and negative reactions
-     Therefore Stock Cultures

- PPTC, Wellington, NZ

## 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

- PPTC, Wellington, NZ

**Notes:**
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??

## 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

## Temperature Chart:Incubator

**Temperature Chart:Incubator**

- PPTC, Wellington, NZ

## Temperature Chart: Refrigerator

**Temperature Chart: Refrigerator**

- PPTC, Wellington, NZ

## 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

## Antimicrobial Susceptibility Testing

**Antimicrobial Susceptibility Testing**

- PPTC, Wellington, NZ

## 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

- PPTC, Wellington, NZ

**Notes:**
I think you could include a pretty long list here, that are worldwide in application.

## 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

- PPTC, Wellington, NZ

**Notes:**
Establish patterns in your patient population and advise health care providers.

So providers can initiate treatment if necessary before susceptibility testing is complete

## QC in Blood Transfusion Service

- PPTC, Wellington, NZ

## Blood Transfusion Service

- Donors

- Recipients

- Safety Precautions

- Recruit – Screen – Bleed 	test – process – Xmatch	transfuse – follow up

- Hospital

- ?

- Government

- Policies

- Regulation

**FUNDING**

**Blood Transfusion Service**

- Blood Bank

- PPTC, Wellington, NZ

## QC in Blood Bank Technology

- Donor services
- Blood grouping
- Crossmatch & antibody screening
- Transfusion

- PPTC, Wellington, NZ

## QC in Blood Bank

- Positive and negative controls on all tests
- Reverse grouping
- Good documentation, SOPs etc
- Equipment monitoring, calibration, maintenance

- PPTC, Wellington, NZ

## QC of Rapid Tests for Infectious Diseases

**QC of Rapid Tests for Infectious Diseases**

- PPTC, Wellington, NZ

## Infectious Diseases Serology QC of Rapid Methods 

- IQC
- Positive controls
- Negative controls
- How often?
- Where do you get the controls from?

- PPTC, Wellington, NZ

## Slide 30

- PPTC, Wellington, NZ

## 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

- PPTC, Wellington, NZ

**Notes:**
Qualitative tests
Tests that do not have measurable endpoints, for example:
Growth-no growth
Positive-negative
Color change

## 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

## 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