Quality Control and Quality

Assurance for Antibiotic Testing26 Sep 2013

Microbiology Technical Workshop

Lily Ng Siew Yong

Quality assurance

“practice of assessing

performance in all

steps of the process to

promote excellent

outcome in medical

care”

Quality control

“aggregate of processes and techniques to

detect, reduce, and correct deficiencies in an

analytical process.”

Quality Assurance

Processes

With thanks to Derek Brown @ EUCAST Educational Workshop: 31 March 2012

Quality

Standard document-

ation

External Quality

Assurance

Internal Quality

Assurance

Education & Training

Validation

Evaluation

Routine Quality Control

External quality assurance

The challenge of laboratory procedures with

specimens of known but undisclosed content

External laboratory

Or organization

Participating

laboratory

Prepares sample and sends

to participants

Receives sample and

performs testing

Reports resultsReceives and

analyses results

Prepares

report

Analyses reports

& deficiencies

Institutes

corrective actions

EQA

Examples of EQA organizations

• College of American Pathologists

• Royal College of Pathologists (Australasia)

• UKNEQAS

• Local reference laboratories

EQA: benefits

• Independent assessment of performance

• Assessment of performance over time

• Comparison with other laboratories

• Highlights problem areas

• Performance related to guidelines and methods

EQA: benefits

• International differences highlighted

• Gives practical experience of difficult tests

(especially if resistance is uncommon)

• Provides background information and guidance

on appropriate methods

• Performance indicator for accreditation

EQA: limitations

• 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

EQA: @ CGH Laboratory

• Survey subscription based on services offered

• Survey sample management

• Result submission management

• Performance assessment

Internal Quality Assurance

The challenge of laboratory procedures by repeat

testing of specimens of unknown content

Sample

blinded

routine

testing

routine

testing

results results

reported compare

&

evaluate

Internal Quality Assurance

The challenge of laboratory procedures by repeat

testing of specimens of unknown content

Sample Sample

blinded

routine

testing

routine

testing

results results

reported compare

&

evaluate

blinded

routine

testing

routine

testing

results results

reported compare

&

evaluate

Internal Quality Assurance

The challenge of laboratory procedures with spiked

specimens

Spiked sample

Routine testing

results

reported

Compare & evaluate

IQA: Benefits

• Check of laboratory processes

• Identifies:

• typographical errors

• Inconsistencies between different

technologists

• process errors

IQA: Practical issues

• Different organisms picked from mixture on primary plates

• Borderline susceptibility leads to variation

• Discrepancies with “difficult” tests

• Labor intensive

• Sample variability (stored samples)

IQA: @ CGH Laboratory

Target: 50 specimens issued monthly

Frequent issues:

Variation in zone diameters

Enumeration of cells

Urine viable count

Audit

Processes

Documentation

Skills

Knowledge

check - inspect - verify

Audit: @ CGH Laboratory

Accreditation audit

Internal surveillance

Target 10 % of total test specimens

July 2013: 1,198 of 13,209 specimens

Frequent issues:

Variation in zone diameters

Enumeration of cells

Urine viable count

Audit: @ CGH Laboratory

Errors

Internal surveillance

• 10 % of total test specimens

July statistics: 1,198 of 13,209 specimens

Documentation

Standard operating

procedures

• user-friendly, not

reference text!

• updated regularly

• document control

Readily accessible

Examples from:

WHO SOP (SE Asia)

http://apps.searo.who.int/PDS_DOCS/B0217.pdf

HPA (UK) SOP repository

http://www.hpa.org.uk/SMI

Mount Sinai SOP

http://microbiology.mtsinai.on.ca/manual/anti/ind

ex.shtml

Documentation

Standard operating

procedures

user-friendly, not

reference text!

updated regularly

document control

Readily accessible

Examples from:

http://apps.searo.who.int/PDS_DOCS/B0217.pd

f

http://www.hpa.org.uk/SMI

Documentation

Standard operating

procedures

user-friendly, not

reference text!

updated regularly

document control

Readily accessible

hard copy

soft copy

Evaluation & Validation

For new testing methods / antibiotics introduced

into laboratory

Analytic accuracyCompare new against

“gold standard”

Precision Repeatibility

Evaluation & Validation @

CGH Laboratory

Introducing use of yeast AST testing by Vitek

Analytic accuracy

Compare results obtained by Vitek

against reference microbroth dilution

method using a range of various

species

Precision 20 consecutive days of parallel testing

www.hpa.org.uk/webc/hpawebfile/h

paweb_c/1317131674973

Education & Training

Competency

Define skills to be assessed

Define how to assess

Define who will assess

Documentation

Remediation

Continuing professional education

Skills upgrading

ReferenceCompetency Assessment in the Clinical Microbiology Laboratory. Clin. Microbiol. Rev. July 2004 vol. 17 no. 3, 681-694

Training topics

Importance of proper technique for AST Lab reports vs clinical impact of Staphylococcal AST

Observation of resistance mechanisms

expression in Proteuses

Interpretation and reporting of test results for

Enterococcal AST

Antimicrobials and the beta lactam family drug

family

Interpretation and reporting of test results for

Enterobacteriaceae AST

Extended spectrum beta lactamasesInterpretation and reporting of test results for

non-Enterobacteriaceae ASTcs

Staph lugdunensis:

significance, identification, and susceptibility

Identification, susceptibility testing and result

interpretation of Strep pneumoniae

ampC beta lactamasesMIC determination by macrobroth and microbroth

methods

Penicillin binding proteins in relation to

staphylococcal growth and drug resistanceMicroscan testing

Antimicrobial testing and reading of test

findings

Drug options, result interpretation and reporting for

Staphylococcal AST

Education & Training @

CGH Laboratory

Insert page of CME AST listing here

Microbiology Training Record

DateTraining

CategoryTopic Trainer Hr LNG GHT ELC HYX HJ SMF LHZ TSY SFM NAP OJL

12/03/2013 Talk Importance of proper technique for AST LNG 0.5 Trainer p p AL p p p OFF p p

26/03/2013 PracticalObservation of resistance machanisms

expression in ProteusesLNG 1 Trainer p p p p p p p p p

11/04/2013 PowerpointAntimicrobials and the beta lactam family

drug familyHJ / LNG 0.5 Trainer P P P Trainer P P P P P

17/04/2013 Powerpoint Extended spectrum beta lactamases HJ / LNG 1 Trainer P AL P Trainer P P P P

22/04/2013 TalkStaph lugdunensis: significance,

identification, and susceptibilityLNG 1 Trainer P P P P P P P P P

24/04/2013 Powerpoint ampC beta lactamases HJ / LNG 1 Trainer P P P Trainer P P P OFF P

29/05/2013 TalkPenicillin binding proteins in relation to

staphylococcal growth and drug resistanceLNG 0.5 Trainer P P AL P P P P P P

30/05/2013 PowerpointAntimicrobial testing and reading of test

findingsHJ / LNG 0.5 Trainer P P AL Trainer P P P P P

11/06/2013 Talk, part 1Drug options, result interpretation and

reporting for Staphylococcal AST(incl FOX vs OX, E vs CC, Quinolones)

LNG 0.5 Speaker P P P P P P P AL P

11/06/2013 Talk, part 2Lab reports vs clinical impact of

Staphylococcal AST(incl TGC, RA5, FU, Gm, SXT)

LNG 0.5 Speaker P P P P P P P AL P Quality Control

Antibiotic testing

Media

Temperature

Organism

Disc potency

Atmosphere

QC: Antibiotic testing

Specified routine quality control strains are used

to monitor test performance

Quality control strains must be from a reliable

source

Proper storage to maintain characteristics

QC Strains: specific tests QC Disc: acceptable ranges

Acceptable range for ATCC strains

QC Disc: acceptable ranges QC Disc: testing

Westgard rules

multiple rules used to monitor a charted process

determines if the process is within acceptable

limits

Westgard relevant

10x

reject when 10 consecutive

control measurements fall

on one side of the mean.

QC Disc: monitoring QC Disc: failures

ID cause

Cause found:

repeat x 01

Repeat ok = case

close

Repeat out of

range

repeat

No obvious

cause

5 consecutive

days

All within range

= case close

≥1 out of range Re-examine

Antibiotic testing:

Common sources of error

Media• pH

• Thickness

• Storage

• Contamination

• Wrong media

Antibiotics• Storage

• Wrong disc

QC strains• Wrong strains

• Inocula

• Storage

• Contamination

• Age

Procedures• Incubation conditions

• Disc placement

• transcription

Antibiotic testing:

Common sources of error

Media• Storage

• Thickness

• Contamination

• pH

• Wrong media

Antibiotics• Storage

• Wrong disc

QC strains• Wrong strains

• Inocula

• Storage

• Contamination

• Age

Procedures• Incubation conditions

• Disc placement

• transcription

Antibiotic testing:

Common sources of error

Media• Storage

• Thickness

• Contamination

• pH

• Wrong media

Antibiotics• Storage

• Wrong disc

QC strains• Age

• Storage

• Inocula

• Contamination

• Wrong strains

Procedures• Incubation conditions

• Disc placement

• transcription

Antibiotic testing:

Common sources of error

Media• Storage

• Thickness

• Contamination

• pH

• Wrong media

Antibiotics• Storage

• Wrong disc

QC strains• Wrong strains

• Inocula

• Storage

• Contamination

• Age

Procedures• Disc placement

• Incubation condition

• transcription

QC Disc: Troubleshooting QC of Automated Systems

• Use the recommended quality control strains

• Follow manufacturer’s instructions

• Purity check of used inocula

Restricted range of test concentrations means that

the available range may not include the MIC of the

control strain.

Some concluding thoughts

Quality Assurance

Quality measure Effort (%)

Clinically relevant testing strategies 15

Testing of reference QC strains 15

Technical competency 15

Organism antibiogram verification 15

Supervisor review of results 15

Procedure manual 10

Cumulative antibiogram 5

Proficiency surveys 5

Other 5

Rankin I. D. (2005). Quality Assurance/Quality Control (QA/QC) In: Coyle M. B. (ed.) Manual of Antimicrobial Susceptibility Testing. 1st ed, Washington, D.C.: American Society for Microbiology; 63-89.

Conclusion

Can we afford

quality assurance in

microbiology laboratories?

Can we afford NOT TO HAVE

quality assurance in

microbiology laboratories?

“15% of Microbiology reports are wrong!”Journal of Hospital Infection. Vol 30, Supp, June 1995, Pages 364–371

Resources

WHO Laboratory Quality Management System

Handbook 2011 http://whqlibdoc.who.int/publications/2011/9789241548274_eng.pdf

CLSI M40 susceptibility testing

www.clsi.org

EUCAST quality tables

www.eucast.org/antimicrobial_susceptibility_testing/qc_tables/

General Review

http://www.intechopen.com/books/latest-research-into-quality-

control/quality-assurance-in-antimicrobial-susceptibility-testing#B23