Molecular and Growth-Based Drug Susceptibility Testing of Mycobacterium tuberculosis Complex for Ethambutol Resistance in the United States
Table 1
Comparison of PHL growth-based DST with CDC’s molecular detection and growth-based DST results for EMB.
PHL growth-based DST result for EMB
CDC molecular result for embB (amino acid change)
CDC’s agar proportion result (number of MTBC samples)
Resistant
Susceptible
No growth
Contaminated
Total number of samples
Resistant
Met306Ile
4
0
3
0
7
Met306Ile, Asp328Gly
0
0
1
0
1
Met306Ile, Gly406Ala
1
0
0
0
1
Met306Val
9
0
3
1
13
Phe330Leu
1
0
0
0
1
Tyr334His
2
0
0
0
2
Ser347Thr
1
0
0
0
1
Asp354Ala
2
0
1
0
3
Glu378Ala
0
1
0
0
1
Gly406Ala
2
0
0
0
2
Gly406Asp
1
0
0
0
1
No mutation
4
3
0
1
8
Not performed
2
0
0
0
2
Susceptible
Gly294Gly
0
1
0
0
1
Asn296Tyr
1
0
0
0
1
Met306Ile
2
1
1
0
4
Met306Val
4
0
0
0
4
Val309Ile
0
0
1
0
1
Leu355Leu
0
1
0
0
1
Leu355Leu, Glu378Ala
0
3
0
0
3
Glu378Ala
0
9
4
2
15
Gly406Ala
0
2
0
0
2
Gly406Cys
2
1
0
0
3
Gly406Ser
1
0
0
0
1
No mutation
6
105
2
9
122
Not performed
0
9
0
1
10
Total
45
136
16
14
211
PHL: public health laboratory; DST: drug susceptibility testing; CDC: Centers for Disease Control and Prevention; EMB: ethambutol; MTBC: Mycobacterium tuberculosis complex.
