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Table 1 Classification of the tested strains

From: Evaluation of a microcolony growth monitoring method for the rapid determination of ethambutol resistance in Mycobacterium tuberculosis

strain

SMI Strain number

Threshold concentration (mg/L) †

Microcolony growth-based classification (This study)

SMI classification

1

XTB 10-172

1

S

S

2

XTB 09-045

4

I

I

3

XTB 09-023

16

R

R

4

XTB 09-060

16

R

R

22#

XTB 09-060

>8

R

R

24#

XTB 09-060

>8

R

R

5

XTB 10-167

≤1

S

S

6

XTB 10-166

4

I

S

7

XTB 10-158

≤2

S

S

8

XTB 09-109

>8

R

R

9

XTB 09-108

8

I/R*

I

10

BTB 09-554

>8

R

R

11

BTB 11-250

4

I

I

12

BTB 11-214

>4

R

R

13

BTB 11-145

2

S

S

14

BTB 11-421

2

S

S

15

XTB 10-170

>8

R

R

23#

XTB 10-170

>4

R

R

16

BTB 11-416

4

I

S/I

17

BTB 11-417

≤1

S

S

18

BTB 11-418

≤1

S

S

19

BTB 11-419

≤1

S

S

20

BTB 11-420

≤1

S

S

21

BTB09-553

>4

R

R

  1. Strains 1–4: reference strains, strains 5–24: blinded strains. † Threshold concentration, lowest concentration tested at which >40% reduction in growth rate compared to control (no EMB) was recorded. Where 40% reduction in growth rate was reached at the lowest concentration tested a ≤ symbol precedes the concentration, Where the threshold was not reached at the highest concentration tested, this is indicated by a > symbol. *4 mg/L missing due to contamination. When retested, strain 9 was correctly classified as intermediate. # Strains 22 and 24, and strain 23 were (unknown) duplicates of strain 4 and 15, respectively. The 2 results discordant between the microcolony growth-based classification and the SMI classifications are indicated in boldface.
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BMC Infectious Diseases

ISSN: 1471-2334

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