BDQ MIC to MDR
The distribution of MDR isolates at the MIC of BDQ was shown in Figure 1. Among the 205 MDR isolates, the number of bacteria showing MIC>0.25 μg/ml as determined by BDQ resistance was 4.4% (9/205). The MIC50 and MIC90 values were 0.031 μg/ml and 0.125 μg/ml, respectively.
Clinical Data Analysis of MDR Isolates
Demographic and clinical characteristics of MDR isolates patients were summarized in Table 1. For the 205 MDR patients, 55 (26.8%) were from male patients, and there were 50 (24.4%) new cases and 155 (75.6%) re-treated cases. The resistance rate of BDQ (4.4%, 9/205) was lower than that of commonly used first- and second-line drugs with SM (72.2%, 148/205), EMB (37.6%, 77/205), OFX (42.0%, 86/205) and KM (14.6%, 30/205). Of the 9 BDQ resistant isolates, the proportion of ancient Beijing strains (88.9%, 8/9) was significantly higher than that of modern Beijing strains (11.1%, 1/9) (P <0.01), and the number of OFX resistant isolates was significantly higher than that of OFX sensitive isolates (P <0.01).
Table 1 Differences of characteristics between BDQR and BDQS MDR strains
|
Characteristics
|
No. (%) of isolates (n=205)
|
No. (%) of isolates
|
BDQR
(n=9)
|
BDQS
(n=196)
|
OR
|
P
|
(95%CI)
|
Sex
|
|
|
|
|
|
Female
|
55(26.8)
|
3(33.3)
|
52(26.5)
|
Ref.
|
|
Male
|
150(73.2)
|
6(66.7)
|
144(73.5)
|
0.72(0.17-2.99)
|
0.95
|
Age (years)
|
|
|
|
|
|
≤40
|
69(33.7)
|
4(44.4)
|
65(33.2)
|
Ref.
|
|
41-59
|
96(46.8)
|
3(33.3)
|
93(47.4)
|
0.52(0.11-2.42)
|
0.65
|
≥60
|
40(19.5)
|
2(22.2)
|
38(19.4)
|
0.86(0.15-4.89)
|
1.00
|
Lineage
|
|
|
|
|
|
Lineage 4
|
37(18.0)
|
0(0.0)
|
37(18.9)
|
Ref.
|
|
Lineage 2
|
168(82.0)
|
9(100.0)
|
159(8.1)
|
0.95(0.91-0.98)
|
0.32
|
Genotype
|
|
|
|
|
|
Modern Beijing
|
98(47.8)
|
1(11.1)
|
97(49.5)
|
Ref.
|
|
Ancient Beijing
|
72(35.1)
|
8(88.9)
|
64(32.7)
|
12.13(1.48-99.28)
|
<0.01
|
Non-Beijing
|
35(17.1)
|
0(0.0)
|
35(17.8)
|
1.01(0.99-1.03)
|
1.00
|
Treatment History
|
|
|
|
|
|
New case
|
50(24.4)
|
3(33.3)
|
47(24.0)
|
Ref.
|
|
Re-treated
|
155(75.6)
|
6(66.7)
|
149(76.0)
|
0.63(0.15-2.62)
|
0.81
|
Lung Cavitation
|
|
|
|
|
|
No
|
124(60.5)
|
6(66.7)
|
118(60.2)
|
Ref.
|
|
Yes
|
81(39.5)
|
3(33.3)
|
78(39.8)
|
0.76(0.18-3.11)
|
0.97
|
Diabetes Mellitus
|
|
|
|
|
|
No
|
192(93.7)
|
7(77.8)
|
185(94.4)
|
Ref.
|
|
Yes
|
13(6.3)
|
2(22.2)
|
11(5.6)
|
4.81(0.89-25.90)
|
0.10
|
Previous exposure to:
|
|
|
|
|
|
None
|
16(7.8)
|
1(11.1)
|
15(7.7)
|
Ref.
|
|
FL drugs
|
124(60.5)
|
5(55.6)
|
119(60.7)
|
0.63(0.07-5.76)
|
0.52
|
FL and SL drugs
|
65(31.7)
|
3(33.3)
|
62(31.6)
|
0.73(0.07-7.48)
|
1.00
|
Resistance to:
|
|
|
|
|
|
SM
|
148(72.2)
|
7(77.8)
|
141(71.9)
|
4.81(0.89-25.91)
|
0.10
|
EMB
|
77(37.6)
|
5(55.6)
|
72(36.7)
|
2.15(0.56-8.28)
|
0.43
|
OFX
|
86(42.0)
|
8(88.9)
|
78(39.8)
|
12.10(1.48-98.68)
|
<0.01
|
KM
|
30(14.6)
|
1(11.1)
|
29(14.8)
|
0.72(0.09-5.97)
|
1.00
|
MDR against BDQ in different resistance pattern
The MIC of BDQ resistant isolates against SM, EMB, KM and OFX was shown in table 2. The 31 isolates sensitive to SM, EMB, KM and OFX were all susceptibility to BDQ. As the number of drug resistance increases, the drug resistance rate of BDQ increased from 0% to 14.4%. Of the 86 OFX resistant isolates, 8 isolates were XDR with the resistance rate of 9.3% (8/86). And the resistance rate of BDQ in OFX resistant isolates (9.3%) was higher than that in SM resistant isolates (4.7%), EMB resistant isolates (6.5%), and KM resistant isolates (3.3%). The resistance rate of BDQ in isolates resistant to any first and second line drug (8.9%) was higher than that in isolates resistant to first line drugs (7.7%) and second line drugs (1.2%), respectively.
WGS Identification of BDQ Resistance-Related Mutations
The BDQ-resistant mutants were performed by WGS in 205 MDR isolates (table 3). No mutations within the atpE, pepQ, and Rv1979 gene were observed in 9 BDQ resistant isolates. Six BDQ resistant isolates (66.7%, 6/9) and two BDQ susceptible isolates (1.0%, 2/196) carried mutations in Rv0678, which has statistical significance. A total of 4 mutations types were identified in BDQ resistant isolates, including A152G mutation causing Gln51Arg amino acid change (50%, 3/6), T56C mutation causing Phe19Ser amino acid change (16.7%, 1/6), GA492 insertion (16.7%, 1/6), and A274 insertion (16.7%, 1/6). Besides, G307A causing Gly103Ser amino acid change and G184A causing Ala62Thr amino acid change in the Rv0678 gene were identified in BDQ sensitive isolates. The six BDQ resistant isolates with mutations in Rv0678 gene all belonged to ancient Beijing genotype, and were resistant to at least two drugs in table 4. Both of the two BDQ susceptible isolates with mutations in Rv0678 gene, one non-Beijing and one mordern Beijing genotype, were resistant to SM.
Genotypic predictions
As shown in table 5, the sensitivity of WGS prediction for BDQ resistance was 66.7%, the specificity was 99.0%, the positive predictive value was 75.0%, and the negative predictive value was 98.5%.
Table 2 MIC distribution of BDQ resistant isolates against SM, EMB, KM and OFX
Drug resistance profile
|
No. of strains
|
No. of strains with different MIC (μg/ml)
|
No. (%) of BDQ resistant strains
|
≤0.008
|
0.016
|
0.031
|
0.063
|
0.125
|
0.25
|
0.5
|
1
|
2
|
4
|
8
|
All isolates
|
205
|
8
|
28
|
77
|
50
|
26
|
7
|
6
|
3
|
0
|
0
|
0
|
9 (4.4)
|
Fully susceptible isolates
|
31
|
2
|
6
|
13
|
7
|
1
|
2
|
0
|
0
|
0
|
0
|
0
|
0(0)
|
Resistant to one drug
|
56
|
4
|
5
|
22
|
15
|
7
|
2
|
1
|
0
|
0
|
0
|
0
|
1(1.8)
|
Resistant to two drugs
|
76
|
1
|
11
|
30
|
17
|
11
|
3
|
3
|
0
|
0
|
0
|
0
|
3 (3.9)
|
Resistant to three drugs
|
35
|
1
|
4
|
11
|
9
|
5
|
1
|
2
|
2
|
0
|
0
|
0
|
4(11.4)
|
Resistant to four drugs
|
7
|
0
|
2
|
1
|
2
|
1
|
0
|
1
|
0
|
0
|
0
|
0
|
1(14.4)
|
Resistant to SM
|
148
|
3
|
18
|
57
|
35
|
23
|
5
|
6
|
1
|
0
|
0
|
0
|
7(4.7)
|
Resistant to EMB
|
77
|
2
|
9
|
28
|
17
|
12
|
3
|
4
|
1
|
0
|
0
|
0
|
5(6.5)
|
Resistant to OFX(pre-XDR)
|
86
|
2
|
13
|
27
|
23
|
11
|
2
|
6
|
2
|
0
|
0
|
0
|
8(9.3)
|
Resistant to KM
|
30
|
2
|
7
|
7
|
9
|
2
|
1
|
1
|
0
|
0
|
0
|
0
|
1(3.3)
|
Resistant to SM and (or) EMB
|
82
|
4
|
8
|
35
|
18
|
13
|
3
|
1
|
0
|
0
|
0
|
0
|
1(1.2)
|
Resistant to KM and (or) OFX
|
13
|
1
|
3
|
3
|
4
|
1
|
0
|
1
|
0
|
0
|
0
|
0
|
1(7.7)
|
Resistant to any first and second line drugs
|
79
|
1
|
11
|
26
|
21
|
10
|
3
|
5
|
2
|
0
|
0
|
0
|
7(8.9)
|
Table 3 Mutation analysis of BDQ resistant genes among 205 MDR isolates
Resistance pattern
|
Isolate number
|
Gene mutation type
|
No. of isolates (%)
|
MIC of BDQ (μg/ml)
|
atpE
|
Rv0678
|
pepQ
|
Rv1979
|
BDQ resistant isolates (9)
|
22A050, 22A133, 22A148
|
WT
|
CAG152CGG Gln51Arg
|
WT
|
WT
|
3
|
0.500
|
22A118
|
WT
|
TTC56TCC Phe19Ser
|
WT
|
WT
|
1
|
0.500
|
22A177
|
WT
|
492 position ins_GA
|
WT
|
WT
|
1
|
1.000
|
22A180
|
WT
|
274 position ins -A
|
WT
|
WT
|
1
|
1.000
|
Total
|
|
|
|
|
|
6 (66.7)a
|
0.500-1.000
|
BDQ sensitive isolates (196)
|
22A076
|
WT
|
GGC307AGC Gly103Ser
|
WT
|
WT
|
1
|
0.125
|
22A079
|
WT
|
GCC184ACC Ala62Thr
|
WT
|
WT
|
1
|
0.250
|
22A128
|
WT
|
WT
|
GCC411GCT Ala137Ala
|
WT
|
1
|
0.031
|
22A174
|
WT
|
WT
|
GAA1080GAT/Glu360Asp
|
WT
|
1
|
0.016
|
22A012, 22A025, 22A030, 22A032, 22A041
|
WT
|
WT
|
WT
|
GTT1276ATT/Val426lle
|
5
|
0.031-0.063
|
22A222
|
WT
|
WT
|
WT
|
C(-70)G
|
1
|
0.063
|
22A196
|
WT
|
WT
|
WT
|
GCG717GCA/Ala239Ala
|
1
|
0.063
|
22A005
|
WT
|
WT
|
WT
|
TCG785TTG/Ser262Leu
|
1
|
0.016
|
22A227
|
WT
|
WT
|
WT
|
GTC286ATC/Val96lle
|
1
|
0.031
|
22A204
|
WT
|
WT
|
WT
|
GCC449GTC/Ala150Val
|
1
|
0.250
|
22A039
|
WT
|
WT
|
WT
|
GTT155GGT/Val52Gly
|
1
|
0.031
|
22A016, 22A029, 22A201, 22A220, 22A223
|
WT
|
WT
|
WT
|
WT
|
5
|
≤0.008-0.031
|
22A006, 22A009
|
WT
|
WT
|
WT
|
WT
|
2
|
0.031
|
22A044
|
WT
|
WT
|
WT
|
WT
|
1
|
0.016
|
22A206
|
WT
|
WT
|
WT
|
WT
|
1
|
0.031
|
22A028
|
WT
|
WT
|
WT
|
WT
|
1
|
≤0.008
|
22A008
|
WT
|
WT
|
WT
|
WT
|
1
|
0.031
|
Total
|
|
|
|
|
|
26 (13.3)b
|
≤0.008-0.250
|
Compared a to b: X2=14.795, P<0.001.
Table 4 Drug resistance data of isolates with mutations in Rv0678 gene
Isolate number
|
MIC of BDQ (μg/ml)
|
Drug resistance profile
|
Genotype
|
22A050
|
0.5
|
SM+EMB+OFX
|
Ancient Beijing
|
22A118
|
0.5
|
SM+OFX
|
Ancient Beijing
|
22A133
|
0.5
|
SM+EMB+OFX
|
Ancient Beijing
|
22A148
|
0.5
|
SM+EMB+OFX+KM
|
Ancient Beijing
|
22A177
|
1
|
EMB+OFX+KM
|
Ancient Beijing
|
22A180
|
1
|
SM+EMB+OFX
|
Ancient Beijing
|
22A076
|
0.125
|
SM
|
non-Beijing
|
22A079
|
0.25
|
SM
|
Mordern Beijing
|
Table 5 WGS predictions versus DST phenotype for BDQ
WGS
|
DST phenotype (n)
|
Total
|
Sensitivity(%)
|
Specificity(%)
|
PPV(%)
|
NPV(%)
|
Kappa
|
Resistant(9)
|
Sensitive(196)
|
Mutation
|
6
|
2
|
8
|
66.7(30.9-91.0)
|
99.0(96.0-99.8)
|
75.0(35.6-95.5)
|
98.5(95.3-99.6)
|
0.693
|
Non-mutaion
|
3
|
194
|
197
|