Module 11
Compliance with
established quality
assurance requirements
1
Learning objectives
At the end of this module you will be able to:
explain the three main components of the
QA system and their importance;
adhere to the QC and EQA procedures.
2
Content outline
• Quality assurance (QA) in mycobacteriology:
– internal quality assurance (IQA) or quality control
QC
– external quality assessment (EQA)
– quality improvement (QI)
3
Definitions
• Quality assurance (QA)
System designed to continuously improve the
reliability and efficiency of laboratory services.
Includes internal quality control, external quality
assessment, and quality improvement.
• Quality control (QC)
Includes all means by which the TB laboratory
controls operations (instrument checks, checking
new lots of staining solutions, reagents, media).
4
Definitions
• External quality assessment (EQA):
– participating laboratories assess their
capabilities through panel testing;
– includes on-site evaluation of the laboratory.
5
Definitions
• Quality improvement (QI):
– to permanently remove obstacles to success;
– involves continued monitoring, identifying defects;
– followed by remedial action (e.g. retraining);
– often relies on effective on-site evaluation visits.
6
Quality assurance in
mycobacteriology
System designed to improve:
– reliability
– efficiency
– use
of laboratory services in order to achieve
the required technical quality in laboratory
diagnosis.
7
The process of quality assurance
should be continuous and monitored
Organized according to existing laboratory
network levels:
• Central laboratories
• Intermediate laboratories
• Peripheral laboratories
8
Quality assurance
• Process of effective and systematic
monitoring of all laboratory activities
– establishes limits of acceptable standard of
test performance;
– ensures laboratory data accuracy, reliability,
reproducibility, comparability;
– not for punitive purposes!
QA is the responsibility of all laboratory
technicians and supervisors.
9
Quality assurance should be:
• Practical
• Workable
• Comprehensive
10
QA should be applied to:
•
•
•
•
•
•
•
•
Laboratory arrangement
Human resources (training, health control)
Laboratory equipment
Collection and transport of specimens
Handling of specimens
Reagents and media
Culture procedures
Reporting of results
11
QA – laboratory arrangement
• BSL2/BSL3
• Doors in the laboratory to be kept
closed.
• Work areas, equipment and supplies
arranged for logical and efficient workflow (clean to dirty).
• Benches swabbed at least once a day
with an appropriate disinfectant.
12
QA – laboratory administration
• Use Standard Operating Procedures
(SOPs).
• Keep written procedures in the laboratory
for easy reference.
• Any changes must be dated and initialled
by the laboratory supervisor.
• Retain all records for 2 years.
13
QA – human resources
• Training (retraining)
– before starting
– refreshment
– in case of failure
• Adequate number
14
Training form
(example for
NTP)
15
QA – laboratory equipment
• Equipment should meet the
manufacturer’s claims and specifications.
• Equipment should be calibrated.
• Dated service records must be kept for all
equipment.
• Equipment must be monitored regularly to
ensure constant accuracy and necessary
precision.
16
QC – biological safety cabinet
Daily checks:
•Minimal airflow: 0.38–0.51 metre/second (75–
100 feet/minute) depending on (sub)classification.
•Check the magnehelic gauge in the exhaust
duct for any pressure drop across the
filters; replace the filters when the gauge
indicates that the airflow across the front
opening has dropped below optimal levels.
17
QC – other equipment
• Refrigerator 2–8 ºC / Freezer – 20°C
– record temperature daily;
– clean monthly;
– defrost or check refrigerator and freezer
compartment every 3 months.
• Glassware:
– discard chipped or etched glassware;
– ensure that glassware is free of detergents;
– do not store sterile glassware for more than
3 weeks before it is used.
18
Trimester :
Month
QC model
for
monitoring
temperature
of equipment
Year :
Temp.
Visa
°C
(Initials)
Month
Temp.
Visa
°C
(Initials)
Month
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
10
10
10
11
11
11
12
12
12
13
13
13
14
14
14
15
15
15
16
16
16
17
17
17
18
18
18
19
19
19
20
20
20
21
21
21
22
22
22
23
23
23
24
24
24
25
25
25
26
26
26
27
27
27
28
28
28
29
29
29
30
30
30
31
31
31
Temp.
Visa
°C
(Initials)
19
QA – collection and transport of
specimens
• Process specimens only in response to written
requests – do not consider oral requests.
• Insist on specimen request forms being kept separate
from the specimens.
• Insist on adequately completed request forms and
proper labelling of specimens.
• Differentiate specimens for diagnosis from those for
control of treatment. Lack of this information rules out
the use of monitoring of bacteriological results as a
method of IQA.
20
QC – handling of specimens
• Process sputum specimens in batches
according to centrifuge capacity.
• CAUTION : If delivery of specimens is
delayed, contamination rate will
increase
21
QC – reagents and media
• Discard media that are discoloured or have
bubbles following inspissation.
• Check all batches of media for sterility by
incubation at 35–37 ºC for 48 hours.
• Keep all media in the dark in the refrigerator
and discard unused drug-containing media
after 4 weeks.
• For culture and DST media: check with M.
tuberculosis H37Rv.
• IQC for identification test with M. terrae and
M. tuberculosis H37Rv
22
QC – preparation of
egg-based media
Sensitivity
• The numbers of colonies obtained by inoculating 5 tubes
from a previous batch of media and 5 tubes from a newly
prepared/purchased batch should be comparable.
Sterility
• No bacterial growth should be present 48 hours after the
incubation at 37 ºC of each new batch.
Storage
• Avoid the accumulation of expired media.
• Estimate the number of tubes to be prepared or purchased to
cover culturing needs for about 2 months of work.
• Store media in a cool and humid place, preferably in a
refrigerator at 4 ºC.
23
Media register
Batch Volume
no.
(ml)
Date of:
Sterility
control
Sensitivity control
Preparation Start End
or
of use of
purchase
use
delivery
Contamination
detected
Yes/No
Strain/ Growth detected at Growth detected at
specimen
20 days
60 days
inoculated (no. of colonies)
(no. of colonies)
Control
batch
Present
batch
Control
batch
24
Present
batch
QC – media for DST
Date of batch production: __________
H37Rv
MIC
expected
INH
0.06
µg/ml
RIF
4.0
µg/ml
EMB
0.5
µg/ml
Date:___________
SM
2.0
µg/ml
Signature
MIC
Observed
Additional concentrations tested (µg/ml)
INH 0.025•0.05•0.10
RIF 2.5•5.0•10.0
EMB 0.125•0.25•0.5
SM 0.5•1.0•2.0
25
QC – culture procedures:
decontamination
• Use aliquoted reagent solutions.
• Do not keep all tubes open at the same time.
• Do not reuse the reagent solution aliquots opened
during the work day.
• The total time of contact of the sample with the
decontaminant must be strictly controlled. Too short
a time results in high contamination rates, too long a
time causes loss of viability of the bacilli.
• Be suspicious of several successive positive
specimens or of cultures with few colonies following a
heavily positive culture.
26
QC – reporting of results
• Always check for agreement between the
laboratory register number and the
number written on tubes/slants.
• Use WHO forms for reporting results.
• A copy of the completed final report
should be retained in the laboratory for 2
years.
27
Reporting – turn-around time
• Smear from specimen (fluorochrome or ZN) –
report positive or negative and the staining method
used, preferably with no more than 24 hours delay
from the moment of receipt of specimen in the
laboratory.
• Culture contaminated: report immediately and a
repeat specimen requested.
• Culture-positive and identification of M.
tuberculosis: report immediately.
• Upon completion of the drug susceptibility test –
susceptible or resistant to each test drug.
28
Reporting – turn-around time
• Culture-negative – upon completion of the
incubation protocol (6 weeks for liquid, 8
weeks for solid).
• For solid media:
- at 4 weeks, send an interim report on all
negative stating that another report will be
issued in the event of the specimen becoming
positive later on
- at 8 weeks, issue a final report
29
Daily monitoring – alarm signals
Smear-positive/culture-negative specimens
• What are the possible explanations?
• What are the corrective measures?
Contaminated specimens
• What are the possible explanations?
• What are the corrective measures?
30
Alarms and remedial actions
Smear-positive/culture-negative specimens
• Follow-up?
• If for diagnosis:
– Does this type of result recur?
– Check the quality of the media being used.
– Concentration of decontaminating solution? Time of contact with
specimens? Temperature of incubator?
Contaminated specimens
• Time between specimen collection and processing too long?
– Corrective measures needed in specimen transportation system.
• Contamination of specimens from the same patient?
– Use a harsher decontamination procedure for testing further
specimens from the patient.
31
Daily monitoring – Alarm signals
Recurrent contamination
• What are the possible explanations?
• What are the corrective measures?
Clustering of culture-positive specimens
• What are the possible explanations?
• What are the corrective measures?
32
Alarms and remedial actions
Recurrent contamination
• Check sterility of decontamination reagent solutions.
• Check the whole decontamination process.
• If the problem is traced to the technician performing the
procedure, he or she should be immediately retrained.
Clustering of culture-positive specimens
• Check contamination of decontamination solution
• Check that:
– aliquoted reagent solutions are discarded after single use;
– processing sequence of specimens is maintained, i.e.
smear-positive specimens processed last;
– tubes are not uncapped immediately after removal from
centrifuge;
– supernatants are discarded carefully.
33
Periodic monitoring
• EQA for whole culture process NOT
feasible.
• Necessary to evaluate indicators
monthly.
• DO NOT inoculate H37Rv in specimens
to evaluate the culture process.
34
Periodic monitoring – indicators
Classification of specimens from adult pulmonary TB
patients investigated for diagnosis (not for follow-up):
a. Smear-positive and culture-positive
b.
Smear-positive and culture not done
c.
Smear-negative and culture-positive
d.
Smear-positive and culture-negative
e.
Smear-positive and culture contaminated
f.
Smear not done and culture-positive
35
Periodic monitoring – indicators
Diagnosis of adult pulmonary cases –
for a specific setting
c+f
Contribution of culture to diagnosis = ---------------------------- x 100
a+b+c+d+e+f
Expected contribution: 20%
36
Periodic monitoring – indicators
Diagnosis of adult pulmonary cases –
for a specific setting
c
Contribution of culture to diagnosis = ------------------------- x 100
over microscopy
a+c+d+e
Expected contribution: >20%
(higher with liquid culture)
37
Periodic monitoring – indicators
d
Percentage of smear-positive = --------------------- x 100
and culture-negative cases
a+c+d+e
Expected: 2–3%
38
Periodic monitoring – indicators
contaminated tubes
Percentage contamination = ----------------------------- x 100
all inoculated tubes
Expected: < 5% for solid
<10% for liquid
39
Alarms: what to investigate
Normal value
(%)
Much
higher:
investigate
Much lower:
investigate
Contribution of culture to
bacteriological diagnosis of
tuberculosis
20
A
B and C
Percentage of smear-positive/
culture-negative specimens
2–3
C and D
Not a
problem
< 5% (solid)
< 10% (liquid)
E
F
Indicators of culture
performance
Percentage of contaminated tubes
40
DST QC and indicators
– IQC: Before use, new batches of media
should be tested with a reference strain
– Alarms:
– change in patterns of resistance;
– unusual resistance rate to a drug e.g.
monoresistance to RMP higher than
monoresistance to INH
41
EQA for culture :
• EQA for culture procedure:
Indirect external supervision based on alarm signals,
see above (slide 40) for QC
• EQA of culture media
If low sensitivity in two consecutive controls:
The laboratory is requested not to use or distribute culture
media until the deficiencies are overcome.
Culture media are offered so that the laboratory can
continue its activity
Retraining in culture media preparation procedures should
also be offered, if needed.
42
International EQA for DST
• EQA of NRLs.
• Blinded test of a panel of 20 strains from SRLs.
• Parameters evaluated: sensitivity, specificity,
reproducibility for each drug.
• Minimum agreement of 90% for at least isoniazid
and rifampicin.
• If not reached, re-evaluate crucial points: drugs,
media, procedures, supervision visit.
43
National EQA for DST
• EQA of national laboratories performing
culture.
• Blinded test of the SRL panel of 20 strains
from the NRL.
• Parameters evaluated: sensitivity, specificity,
reproducibility for each drug.
• Minimum agreement of 90% for at least
isoniazid and rifampicin.
• If not reached, re-evaluate crucial points:
drugs, media, procedures, supervision visit.
44
Quality improvement
It is not sufficient in IQC simply to
identify errors or weaknesses in laboratory
services; remedial action must be taken to
permanently eliminate them.
This implies continuous monitoring of
performance, an IQC programme, as well as
a direct supervision programme.
45
Keys to successful quality control
• Adequately trained, interested and
committed staff.
• Common-sense use of practical
procedures.
• Willingness to admit and rectify
mistakes.
• Effective communication.
46
True and false take-home messages
1. Quality assurance is a system
designed to discover and punish
people who don’t work well.
2. It is useful periodically to calculate
indicators to evaluate the performance
of the laboratory.
47
Module review: take-home messages
 A quality assurance (QA) programme is essential for improving the
reliability, efficiency and use of laboratory services in order to achieve
the required technical quality in laboratory diagnosis.
 The process of quality assurance should be continuous and monitored
 Quality assurance is the responsibility of all laboratory technicians and
supervisors.
 It is useful periodically to calculate indicators to evaluate the
performance of the laboratory.
 It is not sufficient in QC simply to identify errors or weaknesses in
laboratory services; remedial action must be taken to permanently
remove them.
48
Self-assessment
• Explain the three main components of the
QA system.
• Which components of the laboratory
workflow should be checked for QC?
49