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pdfCDC Model Performance Evaluation Program (MPEP) for
Mycobacterium tuberculosis Drug Susceptibility Testing
Attachment 13
Final Report
Mycobacterium
tuberculosis Complex
Drug Susceptibility
Testing Program
MARCH
2024
Model Performance
Evaluation Program
Report of Results, March 2024
Purpose
To present results of the U.S. Centers for Disease Control and Prevention (CDC) Model
Performance Evaluation Program (MPEP) for Mycobacterium tuberculosis complex
(MTBC) drug susceptibility testing panel sent to participants in March 2024.
Report Content
Developed and prepared by:
Cortney Stafford, MPH, MT (ASCP), Health Scientist, Laboratory Capacity Team,
Laboratory Branch (LB), Division of TB Elimination (DTBE), National Center for HIV, Viral
Hepatitis, STD, and TB Prevention (NCHHSTP), CDC
Acknowledged contributors from NCHHSTP/DTBE/ LB: Lois Diem, Stephanie Johnston,
Atanaska Marinova-Petkova, Danielle Miller, James Posey, and Angela Starks
Contact Information
Comments and inquiries should be directed to:
TBMPEP@CDC.GOV
404-639-4013
Model Performace Evaluation Program (MPEP) | Tuberculosis (TB) | CDC
Use of trade names and commercial sources is for identification only and does not imply endorsement by
the U.S. Department of Health and Human Services.
Note on Accessibility: Find descriptions and explanations of figures in Appendix 1: Accessible Explanation
of Figures on page 39.
2
Contents
Technical Notes
4
Abbreviations and Acronyms
5
Introduction: Overview of MPEP Final Report
6
Expected Drug Susceptibility Testing Results
7
Equivalent Critical Concentrations
8
Descriptive Information about Participant Laboratories
10
Isolate 2024A
13
Isolate 2024B
18
Isolate 2024C
23
Isolate 2024D
28
Isolate 2024E
33
References
38
Appendix 1: Accessible Explanations of Figures
39
3
Technical Notes
The following information pertains to all tables and figures for the 2024 MTBC isolates A, B, C, D, and E included in
this report.
• The source of data in all tables and figures is the March 2024 MPEP MTBC DST panel.
• First-line and second-line drugs have been separated into individual tables for each isolate. Streptomycin is classified as a
second-line drug for this report.
• Separate tables for molecular testing are included.
• Mutations of the rpoB gene are noted with the M. tuberculosis numbering system.
• Laboratories that use more than one DST method are encouraged to test isolates with each of the available methods and
equivalent critical concentrations. Some laboratories have provided results for multiple DST methods. Consequently, the
number of results for some drugs may be greater than the number of participating laboratories. This report contains all results
reported by participating laboratories.
• The Sensititre® system allows determination of an MIC for each drug in the panel. Laboratories using this method may establish
breakpoints individually, for some drugs, to provide a categorical interpretation of S or R.
• For participant result tables that have drug-method totals equal to 0, results were not received.
• Although data was collected for rifapentine, delamanid, and pretomanid, no laboratories reported growth-based testing for
these drugs. Therefore, these drugs were not included in growth-based tables of participants’ results.
4
Abbreviations and Acronyms
Acronym
Definition
AMK
AP
CAP
CDC
CIP
CLSI
CYS
DNA
DST
EMB
ETA
FQ
INH
KAN
LVX
MDR
MGIT™
MIC
MOX
MPEP
MTBC
PAS
PZA
OFL
R
RBT
RIF
RNA
S
Sensititre®
STR
TB
VersaTREK™
XDR
Amikacin
Agar proportion — performed on Middlebrook 7H10 or 7H11
Capreomycin
U.S. Centers for Disease Control and Prevention
Ciprofloxacin
Clinical and Laboratory Standards Institute
Cycloserine
Deoxyribonucleic acid
Drug susceptibility testing
Ethambutol
Ethionamide
Fluoroquinolone
Isoniazid
Kanamycin
Levofloxacin
Multidrug-resistant
BACTEC™ MGIT™ – Mycobacteria Growth Indicator Tube
Minimum inhibitory concentration
Moxifloxacin
Model Performance Evaluation Program
Mycobacterium tuberculosis complex
P-aminosalicylic acid
Pyrazinamide
Ofloxacin
Resistant
Rifabutin
Rifampin
Ribonucleic acid
Susceptible
Thermo Scientific Sensititre® MYCOTB AST or customized plate
Streptomycin
Tuberculosis
Thermo Scientific VersaTREK™ Myco susceptibility
Extensively drug-resistant
5
Introduction: Overview of MPEP Final Report
The Model Performance Evaluation Program (MPEP) is an educational, self-assessment tool in which five isolates of
M. tuberculosis complex (MTBC) are sent to participating laboratories biannually for staff to monitor their ability to
determine drug resistance among the isolates. It is not a formal, graded proficiency testing program. The associated
report includes results for a subset of laboratories performing drug susceptibility testing (DST) for MTBC in the
United States. MPEP is a voluntary program, and this report reflects data received from participating laboratories.
This aggregate report is prepared in a format that will allow comparison of DST results with those obtained by other
participants using the same methods and drugs, for each isolate. We encourage circulation of this report to personnel
who are either involved with DST or reporting and interpreting results for MTBC.
CDC is neither recommending nor endorsing testing practices reported by participants. For standards, participants
should refer to consensus documents published by the Clinical and Laboratory Standards Institute (CLSI), “M24:
Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes” and “M24S: Performance
Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes” [1,
2]. Additionally, the World Health Organization (WHO) published two technical reports investigating critical
concentrations, by method, for anti-tuberculosis drugs [3, 4].
6
Expected Drug Susceptibility Testing Results
Anticipated growth-based and molecular results for the panel of MTBC isolates sent to participants in March 2024
are shown in the tables below. Although CDC recommends broth-based methods for routine first-line DST of MTBC
isolates, the results obtained by the reference agar proportion method (except for pyrazinamide, in which MGIT™ was
performed) are shown in Table 1. Molecular results obtained by whole genome sequencing are listed in Table 2.
Table 1. Expected Growth-based Results for March 2024 Panel
Isolate
RIF
INH
EMB
PZA
FQ
Second-line Drug Resistances:
2024A
S
R (low-level*)
S
S
S
ETA‡
2024B
S
S
S
S
R‡
2024C
S
R (high-level†)
S
S
S
2024D
R
S
S
S
S
2024E
S
S
S
R
S
RBT
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, ETA=ethionamide, RBT=rifabutin,
S=susceptible, R=resistant.
Resistant at 0.2 µg/ml by agar proportion. See Equivalent Critical Concentration table on page 8 for more information.
*
†
Resistant at 0.2 and 1.0 µg/ml by agar proportion. See Equivalent Critical Concentration table on page 8 for more information.
80% consensus for a single categorical result across all methods reported for this drug of susceptible or resistant was not achieved for these
‡
isolates among participating laboratories.
Table 2. Expected Molecular Results (Mutations Detected in Loci Associated with Resistance) for March 2024 Panel
Isolate
rpoB*
2024A
inhA
katG
pncA
C-15T
2024B
Ala90Val
2024C
2024D
gyrA
Ser315Thr
Ser450Leu
2024E
His57Asp
Note: Empty cell=No mutation detected. High confidence mutations were not detected in these loci: fabG1, embB, ethA, eis, rrs, and tlyA.
M. tuberculosis numbering system used [5, 6]
*
7
Equivalent Critical Concentrations
(Concentrations listed as µg/ml)
Agar Proportion
First-line Drugs
7H10 agar
7H11 agar
Isoniazid
0.2 and 1.0
0.2 and 1.0*
Rifampin
0.5†
1.0
Ethambutol
5.0
7.5
Pyrazinamide
Not recommended
Not recommended
*
NOTE—Critical concentrations as indicated in CLSI M24 document, unless otherwise stated [1].
The higher concentration of INH should be tested as second-line drug after resistance at the critical concentration is detected [1].
*
†
WHO recommended critical concentration of 0.5 µg/ml differs from CLSI critical concentration of 1.0 µg/ml for RIF [1, 4].
Second-line Drugs
7H10 agar
7H11 agar
Streptomycin
2.0
2.0
Levofloxacin
1.0
Not determined
Moxifloxacin
0.5
0.5
Amikacin
4.0
Not determined
Capreomycin
10.0†
10.0¥
Kanamycin
5.0†
6.0¥
Ethionamide
5.0
10.0
Rifabutin
0.5
0.5
p-Aminosalicylic acid
2.0¥
8.0¥
Rifapentine
Not determined*
Not determined*
Bedaquiline
Not determined*
0.25‡
Linezolid
1.0‡
1.0‡
Clofazimine
Not determined*
Not determined*
Delamanid
Not determined*
0.016‡
Pretomanid
Not determined*
Not determined*
†
NOTE—Critical concentrations as indicated in CLSI M24 document [1].
Breakpoints for establishing susceptibility have not been determined.
*
†
CLSI critical concentrations differ from revised WHO recommendations published in 2018 [1, 3].
• For AMK, the WHO recommended critical concentration for 7H10 agar is 2.0 µg/ml.
• For CAP, the WHO recommended critical concentration for 7H10 agar is 4.0 µg/ml and ‘Not determined’ for 7H11 agar.
• For KAN, the WHO recommended critical concentration for 7H10 agar is 4.0 µg/ml.
WHO has withdrawn the recommended critical concentrations for CAP and KAN for 7H11 agar and PAS for 7H10 and 7H11 [3].
¥
‡
Critical concentrations as indicated in WHO 2018 Technical Report on critical concentrations [3].
8
Broth Based Media
First-line Drugs
MGIT™
VersaTREK™
Isoniazid
0.1 (and 0.4*)
0.1 (and 0.4*)
Rifampin
0.5†
1.0
Ethambutol
5.0
5.0 (and 8.0*)
Pyrazinamide
100.0
300.0
NOTE—Critical concentrations as indicated in applicable manufacturer package inserts, unless otherwise stated.
The higher concentration of INH and EMB should be tested after resistance at the critical concentration is detected [1].
*
†
WHO recommended critical concentration of 0.5 µg/ml differs from CLSI critical concentration of 1.0 µg/ml for RIF [4].
Second-line Drugs
MGIT™
Streptomycin
1.0 (and 4.0*)
Levofloxacin
1.0†
Moxifloxacin
0.25
Amikacin
1.0
Capreomycin
2.5
Kanamycin
2.5
Ethionamide
5.0
Cycloserine
16.0¥
p-Aminosalicylic acid
Not recommended†
Rifapentine
Not determined
Bedaquiline
1.0
Linezolid
1.0
Clofazimine
1.0
Delamanid
0.06
Pretomanid
0.5 and 2.0‡
NOTE—Critical concentrations as indicated in WHO 2018 Technical Report on critical concentrations unless noted otherwise [3]. Data for
second-line critical concentrations not available for VersaTREK™.
*
Critical concentration as indicated in applicable manufacturer package insert. The higher concentration of STR should be tested after resistance
at the critical concentration is detected.
†
WHO critical concentrations differ from CLSI M24S recommendations published in 2023 [2, 3].
• For LVX, the CLSI recommended critical concentration for MGIT™ is 1.5 µg/ml.
• For PAS, the CLSI recommended critical concentration for MGIT™ is 4.0 µg/ml.
Critical concentration as indicated in WHO 2024 Module 3: Diagnosis—Rapid diagnostics for tuberculosis detection (Third Edition) [7].
¥
Per WHO 2024 Module 3: Diagnosis—Rapid diagnostics for tuberculosis detection (Third Edition), no growth at 0.5 µg/ml is susceptible; growth
at 0.5 µg/ml and no growth at 2.0 µg/ml is susceptible, but with a comment on uncertainty; growth at 2.0 µg/ml is resistant [7].
‡
9
Descriptive Information about Participant
Laboratories
Primary Classification
This report contains DST results submitted to CDC by panel participants at 55 laboratories in 31 states, all of whom
have participated in previous MPEP panels.
Participants were asked to indicate the primary classification of their laboratory (Figure 1).
Figure 1. Primary Classification of Participating Laboratories, March 2024
Public health laboratory,
43, 78%
Hospital laboratory,
5, 9%
Independent/Reference
laboratory, 4, 7%
Federal government
laboratory, 3, 6%
Annual Number of MTBC Drug Susceptibility Tests Performed
The number of MTBC isolates tested for drug susceptibility by the 55 participants in 2023 (excluding isolates used
for quality control) is shown in Figure 2. In 2023, the counts ranged from 6 to 1,055 tests. Participants at 15 (27%)
laboratories reported testing 50 or fewer DST isolates per year. Laboratories with low MTBC DST volumes are
encouraged to consider referral of testing because of concerns about maintaining proficiency [8].
Number of Laboratories
Responding
Figure 2. Distribution of the Annual Volume of MTBC Isolates Tested for Drug Susceptibility by Participants in
Previous Calendar Year (n=55)
16
14
12
10
8
6
4
2
0
15
14
9
6
5
4
1
≤ 50
51-100
101-150
151-200
201-300
301-500
1
501-1000
≥1, 001
Number of Isolates Tested
10
MTBC Drug Susceptibility Test Methods Performed by Participants
The DST methods that were performed by participating laboratories for this panel of MTBC isolates are displayed in
Figure 3. Of participating laboratories, 31 (56%) reported results for only one method, 18 (33%) reported two methods,
and 6 (11%) reported three susceptibility methods. Fifty-three (96%) participating laboratories indicated use of MGIT™.
Number of Laboratories Responding
Figure 3. MTBC Drug Susceptibility Test Methods Performed (n=86 responses)
60
53
50
40
30
20
16
13
10
3
1
0
MGITTM
Agar Proportion
Sensititre®
VersaTREKTM
Molecular Methods
Drug Susceptibility Test Method
Molecular methods reported by participants are shown in Figure 4. The method performed most frequently (44%) was
targeted DNA sequencing.
Figure 4. Molecular Method Reported (n=16 responses)
Targeted DNA Sequencing, 7, 44%
Burker Line Probe, 1, 6%
Whole Genome
Sequencing, 4, 25%
Cepheid Xpert®, 4, 25%
11
Antituberculosis Drugs Tested by Participants
The number of participating laboratories that reported testing each antituberculosis drug in the March 2024 panel
is presented in Figure 5. CLSI recommends testing a full panel of first-line drugs (rifampin [RIF], isoniazid [INH],
ethambutol [EMB], and pyrazinamide [PZA])[1] because it represents a combination of tests that provides the
clinician with comprehensive information related to the 6- or 9-month four-drug RIPE TB treatment regimen used
for many patients. Laboratories should consider the addition of fluoroquinolones (FQ) to their testing panel as
CDC recommends susceptibility testing for FQ (e.g., moxifloxacin) with use of the alternate 4-month rifapentinemoxifloxacin treatment regimen; RIF may be used as a proxy for rifapentine [9].
Figure 5. Antituberculosis Drugs Tested by Growth-based Method by Participants
Rifampin
Isoniazid
Ethambutol
Pyrazinamide
54
54
54
47
28
Streptomycin
Ofloxacin
Moxifloxacin
Ciprofloxacin
Levofloxacin
8
12
3
8
Capreomycin
Kanamycin
Amikacin
10
9
13
Ethionamide
13
p-aminosalicylic Acid
Rifabutin
Cycloserine
8
12
6
Rifapentine
Bedaquiline
Linezolid
Clofazimine
Delamanid
Pretomanid
0
1
2
2
0
0
0
10
20
30
40
50
60
Number of Laboratories Responding
12
Isolate 2024A
Expected Results:
Drug
Growth-based*
Molecular*
RIF
S
rpoB wild-type
INH
R (low-level†)
inhA C-15T; katG & fabG1 wild-type
EMB
S
embB wild-type
PZA
S
pncA wild-type
FQ
S
gyrA & gyrB wild-type
ETA
R‡
inhA C-15T; ethA wild-type
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, ETA=ethionamide, S=susceptible, R=resistant
Growth-based expected results performed by agar proportion, except for PZA which was performed by MGIT™. Molecular expected results
performed by whole genome sequencing.
*
†
Resistant at 0.2 µg/ml by agar proportion. See Equivalent Critical Concentration table on page 8 for more information.
80% consensus for a single categorical result across all methods reported for this drug of susceptible or resistant was not achieved for these
‡
isolates among participating laboratories.
Isoniazid
DNA sequence analysis of inhA, katG, and fabG1 of Isolate 2024A revealed a C>T point mutation at nucleotide position
-15 of the inhA promoter region; katG and fabG1 were wild-type (i.e., no mutations were detected). The inhA C-15T
mutation is known to cause low-level INH resistance.
Percent Reporting
Resistance
Figure 6. Isolate 2024A: Percent of laboratories reporting INH-Low and INH-High resistance, by growth-based method
100%
80%
60%
1/1
47/49
1/1
7/9
40%
20%
1/28
0/9
0%
INH-Low
INH-High
AP
INH-Low
INH-High
0/1
0/1
INH-Low
MGITTM
INH-High
Sensititre®
INH-Low
INH-High
VersaTREKTM
Method and Drug
Note—Two laboratories performing Sensititre® reported INH MIC value as 0.25 µg/ml (n=2).
13
Ethionamide
Resistance to ETA is commonly due to mutations in the ethA gene or mutations in fabG1 or inhA resulting in crossresistance with INH. DNA sequencing analysis revealed the inhA C-15T mutation; ethA was wild-type (i.e., no mutations
were detected).
Percent Reporting
Resistance
Figure 7. Isolate 2024A: Percent of laboratories reporting ETA resistance, by growth-based method
100%
3/3
80%
60%
40%
4/8
20%
0/1
0%
AP
MGITTM
Sensititre®
Note—Two of the laboratories performing Sensititre® reported an ETA MIC value as 5 µg/ml (n=2), although one laboratory reported ‘No
Interpretation’.
Complete first-line DST, second-line DST, and molecular results submitted by all participants for Isolate 2023F are listed in
Tables 3–10.
Table 3. Isolate 2024A: Participant Results for First-Line DST by AP
Drug
Susceptible
Resistant
Total
Rifampin
10
0
10
Isoniazid—Low
2
7
9
Isoniazid—High
9
0
9
Ethambutol
9
0
9
Table 4. Isolate 2024A: Participant Results for First-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Rifampin
49
0
49*
Isoniazid—Low
2
47
49*
Isoniazid—High
27
1
28
Ethambutol
49
0
49*
Pyrazinamide
43
1
44*†
One additional laboratory reported ‘Contaminated/No Growth’ for RIF, INH-Low, EMB, and PZA by MGIT™.
*
†
One additional laboratory reported ‘No Interpretation’ for PZA by MGIT™.
14
Table 5. Isolate 2024A: Participant Results for First-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Rifampin
2
0
2
Isoniazid—Low
0
1
1
Isoniazid—High
1
0
1*
Ethambutol
2
0
2
*One additional laboratory reported ‘Intermediate’ for INH-High by Sensititre®.
Table 6. Isolate 2024A: Participant Results for First-Line DST by VersaTREKTM
Drug
Susceptible
Resistant
Total
Rifampin
1
0
1
Isoniazid—Low
0
1
1
Isoniazid—High
1
0
1
Ethambutol
1
0
1
Pyrazinamide
1
0
1
Table 7. Isolate 2024A: Participant Results for Second-Line DST by AP
Drug
Susceptible
Resistant
Total
Streptomycin
9
0
9
Ofloxacin
5
0
5
Ciprofloxacin
3
0
3
Moxifloxacin
3
0
3
Levofloxacin
3
0
3
Amikacin
7
0
7
Kanamycin
5
0
5
Capreomycin
6
0
6
Ethionamide
4
4
8
Rifabutin
5
0
5
Cycloserine
4
0
4
p-Aminosalicylic acid
5
0
5
Bedaquiline
0
0
0
Linezolid
0
0
0
Clofazimine
0
0
0
15
Table 8. Isolate 2024A: Participant Results for Second-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Streptomycin
17
0
17
Ofloxacin
1
0
1
Ciprofloxacin
0
0
0
Moxifloxacin
7
0
7
Levofloxacin
4
0
4
Amikacin
2
0
2
Kanamycin
1
0
1
Capreomycin
2
0
2
Ethionamide
0
3
3
Rifabutin
3
0
3
Cycloserine
0
0
0
p-Aminosalicylic acid
0
0
0
Bedaquiline
1
0
1
Linezolid
1
0
1
Clofazimine
2
0
2
Table 9. Isolate 2024A: Participant Results for Second-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Streptomycin
2
0
2*
Ofloxacin
1
0
1*
Ciprofloxacin
0
0
0
Moxifloxacin
1
0
1*†
Levofloxacin
0
0
0*
Amikacin
2
0
2*
Kanamycin
1
0
1*
Capreomycin
1
0
1
Ethionamide
1
0
1*
Rifabutin
2
0
2*
Cycloserine
1
0
1*
p-Aminosalicylic acid
2
0
2*
Bedaquiline
0
0
0
Linezolid
1
0
1
Clofazimine
0
0
0
One additional laboratory reported ‘No Interpretation’ for STR, OFL, MOX, LVX, AMK, KAN, ETA, RBT, CYC, and PAS by Sensititre®.
*
One additional laboratory reported ‘No Interpretation’ for MOX by Sensititre®.
†
16
Table 10. Isolate 2024A: Participant Results for Molecular Testing
Drug
Mutation Not Detected
Mutation Detected
Total
Rifamycins (Rifampin,
Rifabutin, Rifapentine)
13
0
13
Isoniazid
0
10*
10
Ethambutol
6
1
7
Pyrazinamide
6
0
6
Streptomycin
5
0
5
Fluoroquinolones
(Ofloxacin, Ciprofloxacin,
Moxifloxacin,
Levofloxacin)
8
1¥
9
Amikacin
9
0
9
Kanamycin
9
0
9
Capreomycin
8
0
8
Ethionamide
2
4§
6
Cycloserine
1
0
1
p-Aminosalicylic acid
1
0
1
Bedaquiline
5
0
5
Linezolid
5
1€
6
Clofazimine
5
0
5
Delamanid
1
0
1
Pretomanid
0
0
0
†
Nine laboratories specifically noted the detection of inhA C-15T mutation.
*
†
One laboratory noted the detection of embB mutation not associated with resistance.
One laboratory noted the detection of gyrA mutation not associated with resistance.
¥
§
Four laboratories noted the detection of inhA C-15T mutation also associated with ETA resistance.
One laboratory noted the detection of rrl mutation with uncertain significance.
€
17
Isolate 2024B
Expected Results:
Drug
Growth-based*
Molecular*
RIF
S
rpoB wild-type
INH
S
katG, inhA, & fabG1 wild-type
EMB
S
embB wild-type
PZA
S
pncA wild-type
FQ
R‡
gyrA Ala90Val; gyrB wild-type
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, S=susceptible, R=resistant
Growth-based expected results performed by agar proportion, except for PZA which was performed by MGIT™. Molecular expected results
performed by whole genome sequencing.
*
‡
80% consensus for a single categorical result across all methods reported for this drug of susceptible or resistant was not achieved for these
isolates among participating laboratories.
Ofloxacin and Ciprofloxacin
DNA sequencing of gyrA in Isolate 2024B detected a C>T point mutation in gyrA resulting in wild-type alanine being
replaced with valine at codon 90 (Ala90Val). The Ala90Val mutation has been associated with low-level FQ resistance,
and the MIC for isolates with this mutation could be close to the critical concentration tested thereby impacting
reproducibility [3, 10, 11]. Sequencing of the gyrB locus for this isolate revealed no mutations (i.e., wild-type
sequence).
Percent Reporting
Resistance
Figure 8. Isolate 2024B: Percent of laboratories reporting OFL, CIP, MOX, and LVX resistance, by growth-based method
100%
80%
60%
40%
20%
0%
1/1
4/5
2/3
2/3
5/6
2/3
1/1
3/4
0/0
OFL
CIP
MOX
AP
LVX
OFL
CIP
MOX
MGIT
TM
LVX
OFL
0/0
0/1
0/0
CIP
MOX
LVX
Sensititre®
Method and Drug
Note—Three of the laboratories performing Sensititre® reported FQ MIC values for OFL as 8 µg/ml (n=2), MOX as 2 µg/ml (n=3), and LVX as 4 µg/
ml (n=1).
Complete first-line DST, second-line DST, and molecular results submitted by all participants for Isolate 2024B are listed in
Tables 11–18.
18
Table 11. Isolate 2024B: Participant Results for First-Line DST by AP
Drug
Susceptible
Resistant
Total
Rifampin
10
0
10
Isoniazid—Low
9
0
9
Isoniazid—High
9
0
9
Ethambutol
9
0
9
Table 12. Isolate 2024B: Participant Results for First-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Rifampin
49
0
49*
Isoniazid—Low
49
0
49*
Isoniazid—High
19
0
19
Ethambutol
49
0
49*
Pyrazinamide
45
0
45*
*One additional laboratory reported ‘Contaminated/No Growth’ for RIF, INH-Low, EMB, and PZA by MGIT™.
Table 13. Isolate 2024B: Participant Results for First-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Rifampin
2
0
2
Isoniazid—Low
1
0
1
Isoniazid—High
2
0
2
Ethambutol
2
0
2
Table 14. Isolate 2024B: Participant Results for First-Line DST by VersaTREKTM
Drug
Susceptible
Resistant
Total
Rifampin
1
0
1
Isoniazid—Low
1
0
1
Isoniazid—High
1
0
1
Ethambutol
1
0
1
Pyrazinamide
1
0
1
19
Table 15. Isolate 2024B: Participant Results for Second-Line DST by AP
Drug
Susceptible
Resistant
Total
Streptomycin
9
0
9
Ofloxacin
1
4
5
Ciprofloxacin
1
2
3
Moxifloxacin
1
2
3
Levofloxacin
1
2
3
Amikacin
7
0
7
Kanamycin
6
0
6
Capreomycin
6
0
6
Ethionamide
8
0
8
Rifabutin
5
0
5
Cycloserine
4
0
4
p-Aminosalicylic acid
5
0
5
Bedaquiline
0
0
0
Linezolid
0
0
0
Clofazimine
0
0
0
Table 16. Isolate 2024B: Participant Results for Second-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Streptomycin
16
0
16
Ofloxacin
0
1
1
Ciprofloxacin
0
0
0
Moxifloxacin
1
5
6
Levofloxacin
1
3
4
Amikacin
2
0
2
Kanamycin
1
0
1
Capreomycin
2
0
2
Ethionamide
3
0
3
Rifabutin
3
0
3
Cycloserine
0
0
0
p-Aminosalicylic acid
0
0
0
Bedaquiline
1
0
1
Linezolid
1
0
1
Clofazimine
0
* One
additional laboratory reported2
‘No Interpretation’ for MOX by MGIT™.
2
20
Table 17. Isolate 2024B: Participant Results for Second-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Streptomycin
2
0
2*
Ofloxacin
0
1
1*
Ciprofloxacin
0
0
0
Moxifloxacin
1
0
1*
Levofloxacin
0
0
0*
Amikacin
2
0
2*
Kanamycin
1
0
1*
Capreomycin
1
0
1
Ethionamide
1
0
1*
Rifabutin
2
0
2*
Cycloserine
0
0
0*
p-Aminosalicylic acid
2
0
2*
Bedaquiline
0
0
0
Linezolid
1
0
1
Clofazimine
0
0
0
One additional laboratory reported ‘No Interpretation’ for STR, OFL, MOX, LVX, AMK, KAN, ETA, RBT, CYS, and PAS by Sensititre®.
*
21
Table 18. Isolate 2024B: Participant Results for Molecular Testing
Drug
Mutation Not Detected
Mutation Detected
Total
Rifamycins (Rifampin,
Rifabutin, Rifapentine)
13
0
13
Isoniazid
9
1*
10
Ethambutol
7
0
7
Pyrazinamide
6
0
6
Streptomycin
5
0
5
Fluoroquinolones
(Ofloxacin, Ciprofloxacin,
Moxifloxacin,
Levofloxacin)
0
9†
9
Amikacin
9
0
9
Kanamycin
9
0
9
Capreomycin
8
0
8
Ethionamide
6
0
6
Cycloserine
1
0
1
p-Aminosalicylic acid
1
0
1
Bedaquiline
5
0
5
Linezolid
6
0
6
Clofazimine
5
0
5
Delamanid
1
0
1
Pretomanid
0
0
0
This laboratory noted the detection of a silent katG mutation.
*
†
Seven laboratories noted the detection of gyrA Ala90Val mutation.
22
Isolate 2024C
Expected Results:
Drug
Growth-based*
Molecular*
RIF
S
rpoB wild-type
INH
R (high-level )
katG Ser315Leu; inhA & fabG1 wild-type
EMB
S
embB wild-type
PZA
S
pncA wild-type
FQ
S
gyrA & gyrB wild-type
†
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, S=susceptible, R=resistant
Growth-based expected results performed by agar proportion, except for PZA which was performed by MGIT™. Molecular expected results
performed by whole genome sequencing.
*
†
Resistant at 0.2 and 1.0 µg/ml by agar proportion. See Equivalent Critical Concentration table on page 8 for more information.
Isoniazid
DNA sequence analysis of inhA, katG, and fabG1 of Isolate 2024C revealed a G>C point mutation in the katG locus
resulting in wild-type serine being replaced by leucine at codon 315 (Ser315Leu); inhA and fabG1 were wild-type
(i.e., no mutations were detected). The katG Ser315Leu mutation is known to cause high-level INH resistance.
Percent Reporting
Resistance
Figure 9. Isolate 2024C: Percent of laboratories reporting INH-Low and INH-High resistance, by growth-based method
100%
80%
10/10
10/10
49/50
28/29
1/1
2/2
1/1
1/1
INH-Low
INH-High
INH-Low
INH-High
INH-Low
INH-High
INH-Low
INH-High
60%
40%
20%
0%
AP
MGITTM
Sensititre®
VersaTREKTM
Method
Note—Two of the laboratories performing Sensititre® reported INH MIC values as 2 µg/ml (n=2).
Complete first-line DST, second-line DST, and molecular results submitted by all participant for Isolate 2024C are listed in
Tables 19–26.
23
Table 19. Isolate 2024C: Participant Results for First-Line DST by AP
Drug
Susceptible
Resistant
Total
Rifampin
11
0
11
Isoniazid—Low
0
10
10
Isoniazid—High
0
10
10
Ethambutol
10
0
10
Table 20. Isolate 2024C: Participant Results for First-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Rifampin
50
0
50
Isoniazid—Low
1
49
50
Isoniazid—High
1
28
29
Ethambutol
50
0
50
Pyrazinamide
39
4
43*
*One additional laboratory reported ‘Contaminated/No Growth’ and two additional laboratories reported ‘No Interpretation’ for PZA by MGIT™.
Table 21. Isolate 2024C: Participant Results for First-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Rifampin
2
0
2
Isoniazid—Low
0
1
1
Isoniazid—High
0
2
2
Ethambutol
2
0
2
Table 22. Isolate 2024C: Participant Results for First-Line DST by VersaTREKTM
Drug
Susceptible
Resistant
Total
Rifampin
1
0
1
Isoniazid—Low
0
1
1
Isoniazid—High
0
1
1
Ethambutol
1
0
1
Pyrazinamide
1
0
1
24
Table 23. Isolate 2024C: Participant Results for Second-Line DST by AP
Drug
Susceptible
Resistant
Total
Streptomycin
10
0
10
Ofloxacin
5
0
5
Ciprofloxacin
3
0
3
Moxifloxacin
3
0
3
Levofloxacin
3
0
3
Amikacin
7
0
7
Kanamycin
6
0
6
Capreomycin
6
0
6
Ethionamide
8
0
8
Rifabutin
5
0
5
Cycloserine
4
0
4
p-Aminosalicylic acid
5
0
5
Bedaquiline
0
0
0
Linezolid
0
0
0
Clofazimine
0
0
0
Table 24. Isolate 2024C: Participant Results for Second-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Streptomycin
18
0
18
Ofloxacin
1
0
1
Ciprofloxacin
0
0
0
Moxifloxacin
7
0
7
Levofloxacin
4
0
4
Amikacin
3
0
3
Kanamycin
1
0
1
Capreomycin
3
0
3
Ethionamide
4
0
4
Rifabutin
3
0
3
Cycloserine
0
0
0
p-Aminosalicylic acid
0
0
0
Bedaquiline
1
0
1
Linezolid
1
0
1
Clofazimine
2
0
2
25
Table 25. Isolate 2024C: Participant Results for Second-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Streptomycin
2
0
2*
Ofloxacin
1
0
1*
Ciprofloxacin
0
0
0
Moxifloxacin
1
0
1*†
Levofloxacin
1
0
1
Amikacin
2
0
2*
Kanamycin
1
0
1*
Capreomycin
1
0
1*
Ethionamide
1
0
1*
Rifabutin
2
0
2*
Cycloserine
0
0
0*†
p-Aminosalicylic acid
1
0
1*†
Bedaquiline
0
0
0
Linezolid
1
0
1
Clofazimine
0
0
0
One additional laboratory reported ‘No Interpretation’ for STR, OFL, MOX, LVX, AMK, KAN, ETA, RBT, CYC, and PAS by Sensititre®.
*
One additional laboratory reported ‘No Interpretation’ for MOX, CYC, and PAS by Sensititre®.
†
26
Table 26. Isolate 2024C: Participant Results for Molecular Testing
Drug
Mutation Not Detected
Mutation Detected
Total
Rifamycins (Rifampin,
Rifabutin, Rifapentine)
13
0
13
Isoniazid
0
10*
10
Ethambutol
7
0
7
Pyrazinamide
6
0
6
Streptomycin
5
0
5
Fluoroquinolones
(Ofloxacin, Ciprofloxacin,
Moxifloxacin,
Levofloxacin)
8
1†
9
Amikacin
9
0
9
Kanamycin
9
0
9
Capreomycin
8
0
8
Ethionamide
6
0
6
Cycloserine
1
0
1
p-Aminosalicylic acid
1
0
1
Bedaquiline
5
0
5
Linezolid
6
0
6
Clofazimine
5
0
5
Delamanid
1
0
1
Pretomanid
0
0
0
Eight laboratories noted the detection of katG Ser315Leu mutation.
*
This laboratory noted the detection of a gyrA mutation not associated with FQ resistance.
†
27
Isolate 2024D
Expected Results:
Drug
Growth-based*
Molecular*
RIF
R
rpoB Ser450Leu
INH
S
katG, inhA, & fabG1 wild-type
EMB
S
embB wild-type
PZA
S
pncA wild-type
FQ
S
gyrA & gyrB wild-type
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, S=susceptible, R=resistant
*Growth-based expected results performed by agar proportion, except for PZA which was performed by MGIT™. Molecular expected results
performed by whole genome sequencing.
Rifampin
DNA sequence analysis of rpoB in Isolate 2024D revealed a C>T point mutation in codon 450 resulting in wild-type
serine being replaced by leucine (Ser450Leu). Isolates with Ser450Leu mutations are associated with RIF resistance
and should reliably test as resistant in growth-based assays [12-14].
Percent Reporting
Resistance
Figure 10. Isolate 2024D: Percent of laboratories reporting RIF resistance, by growth-based method
100%
80%
11/11
50/50
2/2
1/1
AP
MGITTM
Sensititre®
VersaTREKTM
60%
40%
20%
0%
Method
Note—Two of the laboratories performing Sensititre® reported RIF MIC values as 16.0 µg/ml (n=1) and >16 µg/ml (n=1).
Complete first-line DST, second-line DST, and molecular results submitted by all participants for Isolate 2024D are listed in
Tables 27–34.
28
Table 27. Isolate 2024D: Participant Results for First-Line DST by AP
Drug
Susceptible
Resistant
Total
Rifampin
0
11
11
Isoniazid—Low
9
1
10
Isoniazid—High
10
0
10
Ethambutol
10
0
10
Table 28. Isolate 2024D: Participant Results for First-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Rifampin
0
50
50
Isoniazid—Low
50
0
50
Isoniazid—High
20
0
20
Ethambutol
50
0
50
Pyrazinamide
44
2
46
Table 29. Isolate 2024D: Participant Results for First-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Rifampin
0
2
2
Isoniazid—Low
1
0
1
Isoniazid—High
2
0
2
Ethambutol
2
0
2
Table 30. Isolate 2024D: Participant Results for First-Line DST by VersaTREKTM
Drug
Susceptible
Resistant
Total
Rifampin
0
1
1
Isoniazid—Low
1
0
1
Isoniazid—High
1
0
1
Ethambutol
1
0
1
Pyrazinamide
1
0
1
29
Table 31. Isolate 2024D: Participant Results for Second-Line DST by AP
Drug
Susceptible
Resistant
Total
Streptomycin
10
0
10
Ofloxacin
5
0
5
Ciprofloxacin
3
0
3
Moxifloxacin
3
0
3
Levofloxacin
3
0
3
Amikacin
7
0
7
Kanamycin
6
0
6
Capreomycin
6
0
6
Ethionamide
8
0
8
Rifabutin
0
5
5
Cycloserine
4
0
4
p-Aminosalicylic acid
5
0
5
Bedaquiline
0
0
0
Linezolid
0
0
0
Clofazimine
0
0
0
Table 32. Isolate 2024D: Participant Results for Second-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Streptomycin
17
0
17
Ofloxacin
1
0
1
Ciprofloxacin
0
0
0
Moxifloxacin
7
0
7
Levofloxacin
4
0
4
Amikacin
3
0
3
Kanamycin
1
0
1
Capreomycin
3
0
3
Ethionamide
4
0
4
Rifabutin
4
0
4
Cycloserine
0
0
0
p-Aminosalicylic acid
0
0
0
Bedaquiline
1
0
1
Linezolid
1
0
1
Clofazimine
2
0
2
30
Table 33. Isolate 2024D: Participant Results for Second-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Streptomycin
2
0
2*
Ofloxacin
1
0
1*
Ciprofloxacin
0
0
0
Moxifloxacin
1
0
1*†
Levofloxacin
1
0
1
Amikacin
2
0
2*
Kanamycin
1
0
1*
Capreomycin
1
0
1
Ethionamide
1
0
1*
Rifabutin
0
2
2*
Cycloserine
0
0
0*†
p-Aminosalicylic acid
2
0
2*
Bedaquiline
0
0
0
Linezolid
1
0
1
Clofazimine
0
0
0
One additional laboratory reported ‘No Interpretation’ for STR, OFL, MOX, LVX, AMK, KAN, ETA, RBT, CYC, and PAS by Sensititre®.
*
One additional laboratory reported ‘No Interpretation’ for MOX and CYC by Sensititre®.
†
31
Table 34. Isolate 2024D: Participant Results for Molecular Testing
Drug
Mutation Not Detected
Mutation Detected
Total
Rifamycins (Rifampin,
Rifabutin, Rifapentine)
0
14*
14
Isoniazid
9
1†
10
Ethambutol
7
0
7
Pyrazinamide
6
0
6
Streptomycin
5
0
5
Fluoroquinolones
(Ofloxacin, Ciprofloxacin,
Moxifloxacin,
Levofloxacin)
8
1¥
9
Amikacin
9
0
9
Kanamycin
9
0
9
Capreomycin
8
0
8
Ethionamide
6
0
6
Cycloserine
1
0
1
p-Aminosalicylic acid
1
0
1
Bedaquiline
5
0
5
Linezolid
6
0
6
Clofazimine
5
0
5
Delamanid
1
0
1
Pretomanid
0
0
0
Eight laboratories noted the detection of rpoB Ser450Thr mutation. Additionally, three laboratories performing Xpert® MTB/RIF assay noted
Probe E.
*
This laboratory noted the detection of a silent katG mutation.
†
This laboratory noted the detection of gyrA mutation not associated with FQ resistance.
¥
32
Isolate 2024E
Expected Results:
Drug
Growth-based*
Molecular*
RIF
S
rpoB wild-type
INH
S
katG, inhA & fabG1 wild-type
EMB
S
embB wild-type
PZA
R
pncA His57Asp
FQ
S
gyrA & gyrB wild-type
Note: RIF=rifampin, INH=isoniazid, EMB=ethambutol, PZA=pyrazinamide, FQ=fluoroquinolones, S=susceptible, R=resistant
*Growth-based expected results performed by agar proportion, except for PZA which was performed by MGIT™. Molecular expected results
performed by whole genome sequencing.
Pyrazinamide
DNA sequence analysis of pncA in Isolate 2024E revealed a single point mutation of C>G at nucleotide position 169
of the pncA gene resulting in aspartic acid replacing histidine at codon 57 (His57Asp). M. bovis has inherent
resistance to PZA caused by this characteristic His57Asp mutation. This substitution causes defective pyrazinamidase
activity and confers natural PZA resistance in M. bovis strains, including BCG substrains [15, 16].
Percent Reporting
Resistance
Figure 11. Isolate 2024E: Percent of laboratories reporting PZA resistance, by growth-based method
100%
80%
43/45
1/1
MGITTM
VersaTREKTM
60%
40%
20%
0%
Method
Complete first-line DST, second-line DST, and molecular results submitted by all participants for Isolate 2024E are listed in
Tables 35–42.
33
Table 35. Isolate 2024E: Participant Results for First-Line DST by AP
Drug
Susceptible
Resistant
Total
Rifampin
10
0
10
Isoniazid—Low
9
0
9
Isoniazid—High
9
0
9
Ethambutol
9
0
9
Table 36. Isolate 2024E: Participant Results for First-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Rifampin
50
0
50
Isoniazid—Low
48
2
50
Isoniazid—High
19
0
19
Ethambutol
50
0
50
Pyrazinamide
2
43
45
Table 37. Isolate 2024E: Participant Results for First-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Rifampin
2
0
2
Isoniazid—Low
1
0
1
Isoniazid—High
2
0
2
Ethambutol
2
0
2
Table 38. Isolate 2024E: Participant Results for First-Line DST by VersaTREKTM
Drug
Susceptible
Resistant
Total
Rifampin
1
0
1
Isoniazid—Low
1
0
1
Isoniazid—High
1
0
1
Ethambutol
1
0
1
Pyrazinamide
0
1
1
34
Table 39. Isolate 2024E: Participant Results for Second-Line DST by AP
Drug
Susceptible
Resistant
Total
Streptomycin
9
0
9
Ofloxacin
5
0
5
Ciprofloxacin
3
0
3
Moxifloxacin
3
0
3
Levofloxacin
3
0
3
Amikacin
7
0
7
Kanamycin
6
0
6
Capreomycin
6
0
6
Ethionamide
8
0
8
Rifabutin
5
0
5
Cycloserine
4
0
4
p-Aminosalicylic acid
5
0
5
Bedaquiline
0
0
0
Linezolid
0
0
0
Clofazimine
0
0
0
Table 40. Isolate 2024E: Participant Results for Second-Line DST by MGITTM
Drug
Susceptible
Resistant
Total
Streptomycin
16
0
16
Ofloxacin
1
0
1
Ciprofloxacin
0
0
0
Moxifloxacin
7
0
7
Levofloxacin
4
0
4
Amikacin
2
0
2
Kanamycin
1
0
1
Capreomycin
2
0
2
Ethionamide
2
1
3
Rifabutin
3
0
3
Cycloserine
0
0
0
p-Aminosalicylic acid
0
0
0
Bedaquiline
1
0
1
Linezolid
1
0
1
Clofazimine
2
0
2
35
Table 41. Isolate 2024E: Participant Results for Second-Line DST by Sensititre®
Drug
Susceptible
Resistant
Total
Streptomycin
2
0
2*
Ofloxacin
1
0
1*
Ciprofloxacin
0
0
0
Moxifloxacin
1
0
1*†
Levofloxacin
1
0
1
Amikacin
2
0
2*
Kanamycin
1
0
1*
Capreomycin
1
0
1
Ethionamide
1
0
1*
Rifabutin
2
0
2*
Cycloserine
0
0
0*†
p-Aminosalicylic acid
1
0
1*†
Bedaquiline
0
0
0
Linezolid
1
0
1
Clofazimine
0
0
0
One additional laboratory reported ‘No Interpretation’ for OFL, MOX, AMK, KAN, ETA, RBT, CYC, and PAS by Sensititre®.
*
†
One additional laboratory reported ‘No Interpretation’ for MOX, CYC, and PAS by Sensititre®.
36
Table 42. Isolate 2024E: Participant Results for Molecular Testing
Drug
Mutation Not Detected
Mutation Detected
Total
Rifamycins (Rifampin,
Rifabutin, Rifapentine)
13
0
13
Isoniazid
9
1*
10
Ethambutol
6
†
1
7
Pyrazinamide
0
8¥
8
Streptomycin
5
0
5
Fluoroquinolones
(Ofloxacin, Ciprofloxacin,
Moxifloxacin,
Levofloxacin)
7
2§€
9
Amikacin
9
0
9
Kanamycin
9
0
9
Capreomycin
8
0
8
Ethionamide
6
0
6
Cycloserine
1
0
1
p-Aminosalicylic acid
1
0
1
Bedaquiline
5
0
5
Linezolid
6
0
6
Clofazimine
5
0
5
Delamanid
1
0
1
Pretomanid
0
0
0
This laboratory noted the detection of silent katG mutation.
*
This laboratory noted the detection of silent embB mutation not associated with resistance.
†
Five laboratories noted the detection of pncA His57Asp mutation.
¥
§
One laboratory noted the detection of gyrA mutation not associated with resistance.
One laboratory noted the detection of gyrB mutation with uncertain significance.
€
37
References
1. CLSI, Susceptibility Testing of Mycobacteria, Nocardiae spp., and Other Aerobic Actinomycetes, in 3rd Ed. CLSI Standard M24. 2018,
Clinical and Laboratory Standards Institute: Wayne, PA.
2. CLSI, Performance Standards for Susceptibility Testing of Mycobacteria, Nocardia spp., and Other Aerobic Actinomycetes, in 2nd
edition. CLSI supplement M24S. 2023, Clinical and Laboratory Standards Institute: Wayne, PA.
3. World Health Organization, Technical Report on critical concentrations for drug susceptibility testing of medicines used in the
treatment of drug-resistant tuberculosis. 2018: Geneva.
4. World Health Organization, Technical Report on critical concentrations for drug susceptibility testing of isoniazid and the rifamycins
(rifampicin, rifabutin and rifapentine). 2021: Geneva.
5. Andre, E., et al., Consensus numbering system for the rifampicin resistance-associated rpoB gene mutations in pathogenic mycobacteria. Clin Microbiol Infect, 2017. 23(3): p. 167-172.
6. Association of Public Health Laboratories, Issues in Mycobacterium tuberculosis complex (MTBC) Drug Susceptibility Testing:
Rifampin (RIF), in APHL Issues in Brief: Infectious Diseases. 2019, Association of Public Health Laboratories: Washington, D.C.
7. World Health Organization, Operational Handbook on Tuberculosis. Module 3: Diagnosis—Rapid Diagnostics for Tuberculosis
Detection, Third Edition. 2024, World Health Organization: Geneva.
8. Association of Public Health Laboratories, TB Drug Susceptibility Testing Expert Panel Meeting Summary Report. 2007, Association
of Public Health Laboratories: Washington, D.C.
9. Carr W, K.E., Starks A, Goswami N, Allen L, Winston C., Interim Guidance: 4-Month Rifapentine-Moxifloxacin Regimen for the
Treatment of Drug-Susceptible Pulmonary Tuberculosis — United States, 2022. MMWR Morb Mortal Wkly Rep, 2022(71): p.
285–289.
10. Campbell, P.J., et al., Molecular detection of mutations associated with first- and second-line drug resistance compared with conventional drug susceptibility testing of Mycobacterium tuberculosis. Antimicrob Agents Chemother, 2011. 55(5): p. 2032-41.
11. Maruri, F., et al., A systematic review of gyrase mutations associated with fluoroquinolone-resistant Mycobacterium tuberculosis and
a proposed gyrase numbering system. Journal of Antimicrobial Chemotherapy, 2012. 67(4): p. 819-831.
12. Van Deun, A., et al., Mycobacterium tuberculosis strains with highly discordant rifampin susceptibility test results. J Clin Microbiol,
2009. 47(11): p. 3501-6.
13. Rigouts, L., et al., Rifampin resistance missed in automated liquid culture system for Mycobacterium tuberculosis isolates with
specific rpoB mutations. J Clin Microbiol, 2013. 51(8): p. 2641-5.
14. World Health Organization, Catalogue of mutations in Mycobacterium tuberculosis complex and their association with drug resistance. 2021, World Health Organization: Geneva.
15. Scorpio, A., et al., Rapid differentiation of bovine and human tubercle bacilli based on a characteristic mutation in the bovine
pyrazinamidase gene. J Clin Microbiol, 1997. 35(1): p. 106-10.
16. Somoskovi, A., et al., Sequencing of the pncA gene in members of the Mycobacterium tuberculosis complex has important
diagnostic applications: Identification of a species-specific pncA mutation in "Mycobacterium canettii" and the reliable and rapid
predictor of pyrazinamide resistance. J Clin Microbiol, 2007. 45(2): p. 595-9.
38
Appendix 1: Accessible Explanations of Figures
Figure 1. The primary classification of the 55 laboratories participating in the March 2024 MPEP panel is
shown in this pie chart. The largest slice represents 44 laboratories, or 78% of 55 that have self-classified as a
health department laboratory. The next major slice signifies 5 laboratories, or 9% of 55 that self-classified as hospital
laboratories. The remaining two slices of the pie chart represent 4, or 7% of 55 that self-classified as independent
laboratories; and 3, or 6% of 55 that self-classified as federal government laboratories.
Figure 2. The annual volume of MTBC isolates tested for drug susceptibility by participating laboratories
(N=55) in 2023 is displayed in this vertical bar graph. The vertical y–axis is the number of laboratories responding
and ranges from 0 to 16 using increments of 2. Along the horizontal x-axis are eight vertical bars representing the
number of isolates tested per year. From left to right, 15 laboratories tested less than or equal to 50 isolates per year;
14 laboratories tested between 51 to 100 isolates per year; 6 laboratories tested between 101 to 150 isolates per year;
5 laboratories tested between 151 to 200 isolates per year; 4 laboratories tested between 201 to 300 isolates per year;
1 laboratory tested between 301 to 500 isolates per year; 9 laboratories tested between 501 to 1000 isolates per year;
and 1 laboratory tested greater than or equal to 1,001 isolates per year.
Figure 3. The drug susceptibility testing methods performed by MPEP participants (N=86) are displayed in this
vertical bar graph. The vertical y-axis is the number of laboratories reporting with ranges from 0 to 60, by increments
of 10, and the horizontal x- axis lists the susceptibility testing methods. Each bar represents the number of reporting
laboratories performing a particular drug susceptibility test method. From left to right: 53 performed MGIT™, 13
performed agar proportion, 3 performed Sensititre®, 1 performed VersaTREK™, and 16 performed molecular methods.
Figure 4. The molecular methods performed by MPEP participants (N=16) are displayed in this pie chart. The
largest slice represents the 7 laboratories that performed targeted DNA sequencing. The next three slices represent
4 laboratories that performed the Cepheid Xpert® MTB/RIF assay, 4 laboratories that performed whole genome
sequencing, and 1 laboratory that performed the Bruker line probe assay.
Figure 5. The antituberculosis drugs tested by growth-based method by MPEP participants are displayed in
a horizontal bar graph. The vertical y -axis contains a list of each drug tested and the horizontal x-axis contains
the number of laboratories with ranges from 0 to 60, by increments of 10. There are 22 horizontal bars with each
bar representing the number of laboratories reporting a result for a particular drug for susceptibility testing. 54
laboratories tested rifampin; 54 laboratories tested isoniazid; 54 laboratories tested ethambutol; 47 laboratories tested
pyrazinamide; 28 laboratories tested streptomycin; 8 laboratories tested ofloxacin; 12 laboratories tested moxifloxacin;
3 laboratories tested ciprofloxacin; 8 laboratories tested levofloxacin; 10 laboratories tested capreomycin; 9
laboratories tested kanamycin; 13 laboratories tested amikacin; 13 laboratories tested ethionamide; 8 laboratories
tested PAS; 12 laboratories tested rifabutin; 6 laboratories tested cycloserine; 0 laboratories tested rifapentine; 1
laboratory tested bedaquiline; 2 laboratories tested linezolid; 2 laboratories tested clofazimine; 0 laboratories tested
delamanid; and 0 laboratories tested pretomanid.
Figure 6. The percent of laboratories reporting resistance to isoniazid (low and high concentrations), by
growth-based method, for isolate 2024A is displayed in this vertical bar graph. The vertical y-axis is the percent
of laboratories reporting resistance with ranges from 0% to 100%, by increments of 20, and the horizontal x-axis
lists the method and drugs. Each bar represents the percent of laboratories reporting resistance. From left to right:
laboratories performing agar proportion for INH-Low is 7 of 9 (78%) reporting resistance and INH-High is 0 of 9 (0%)
reporting resistance; laboratories performing MGIT™ for INH-Low is 47 of 49 (96%) reporting resistance and INH-High
is 1 of 28 (4%) reporting resistance; laboratories performing Sensititre® for INH-Low is 1 of 1 (100%) reporting
resistance and INH-High is 0 of 1 (0%) reporting resistance; and laboratories performing VersaTREK™ for INH-Low is 1 of
1 (100%) reporting resistance and INH-High is 0 of 1 (0%) reporting resistance.
39
Figure 7. The percent of laboratories reporting resistance to ethionamide, by growth-based method, for
isolate 2024A is displayed in this vertical bar graph. The vertical y-axis is the percent of laboratories reporting
resistance with ranges from 0% to 100%, by increments of 20, and the horizontal x-axis lists the method. Each bar
represents the percent of laboratories reporting resistance. From left to right: laboratories performing agar proportion
for ethionamide is 4 of 8 (50%) reporting resistance; laboratories performing MGIT™ for ethionamide is 3 of 3 (100%)
reporting resistance; and laboratories performing Sensititre® for ethionamide is 0 of 1 (0%) reporting resistance.
Figure 8. The percent of laboratories reporting resistance to ofloxacin, ciprofloxacin, moxifloxacin, and
levofloxacin, by growth-based method, for isolate 2024B is displayed in this vertical bar graph. The vertical
y-axis is the percent of laboratories reporting resistance with ranges from 0% to 100%, by increments of 20, and the
horizontal x-axis lists the method and drugs. Each bar represents the percent of laboratories reporting resistance. From
left to right: laboratories performing agar proportion for OFL is 4 of 5 (80%) reporting resistance, CIP is 2 of 3 (67%)
reporting resistance, MOX is 2 of 3 (67%) reporting resistance, LVX is 2 of 3 (67%) reporting resistance; laboratories
performing MGIT™ for OFL is 1 of 1 (100%) reporting resistance, CIP is 0 of 0 (0%) reporting resistance, MOX is 5 of 6
(83%) reporting resistance, LVX is 3 of 4 (75%) reporting resistance; and laboratories performing Sensititre® for OFL is
1 of 1 (100%) reporting resistance, CIP is 0 of 0 (0%) reporting resistance, MOX is 0 of 1 (0%) reporting resistance, LVX is
0 of 0 (0%) reporting resistance.
Figure 9. The percent of laboratories reporting resistance to isoniazid (low and high concentrations), by
growth-based method, for isolate 2024C is displayed in this vertical bar graph. The vertical y-axis is the percent
of laboratories reporting resistance with ranges from 0% to 100%, by increments of 20, and the horizontal x-axis
lists the method and drugs. Each bar represents the percent of laboratories reporting resistance. From left to right:
laboratories performing agar proportion for INH-Low is 10 of 10 (100%) reporting resistance and INH-High is 10 of
10 (100%) reporting resistance; laboratories performing MGIT™ for INH-Low is 49 of 50 (98%) reporting resistance
and INH-High is 28 of 29 (97%) reporting resistance; laboratories performing Sensititre® for INH-Low is 1 of 1 (100%)
reporting resistance and INH-High is 2 of 2 (100%) reporting resistance; and laboratories performing VersaTREK™ for
INH-Low is 1 of 1 (100%) reporting resistance and INH-High is 1 of 1 (100%) reporting resistance.
Figure 10. The percent of laboratories reporting resistance to rifampin, by growth-based method, for 2024D is
displayed in this vertical bar graph. The vertical y-axis is the percent of laboratories reporting resistance with ranges
from 0% to 100%, by increments of 20, and the horizontal x-axis lists the method. Each bar represents the percent
of laboratories reporting resistance. From left to right: laboratories performing agar proportion for rifampin is 11 of
11 (100%) reporting resistance; laboratories performing MGIT™ for rifampin is 50 of 50 (100%) reporting resistance;
laboratories performing Sensititre® for rifampin is 2 of 2 (100%) reporting resistance; and laboratories performing
VersaTREK™ for rifampin is 1 of 1 (100%) reporting resistance.
Figure 11. The percent of laboratories reporting resistance to pyrazinamide, by growth-based method, for
isolate 2024E is displayed in this vertical bar graph. The vertical y-axis is the percent of laboratories reporting
resistance with ranges from 0% to 100%, by increments of 20, and the horizontal x-axis lists the method. Each bar
represents the percent of laboratories reporting resistance. From left to right: laboratories performing MGIT™ for
pyrazinamide is 43 of 45 (96%) reporting resistance; and laboratories performing VersaTREK™ for pyrazinamide is 1 of 1
(100%) reporting resistance.
40
| File Type | application/pdf |
| Author | Stafford, Cortney (CDC/NCHHSTP/DTE) |
| File Modified | 2025-07-21 |
| File Created | 2025-02-20 |