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Table 1 Antitubercular drug-resistance mechanismsa

From: Deciphering drug resistance in Mycobacterium tuberculosis using whole-genome sequencing: progress, promise, and challenges

WHO category

Drug or drug class

Resistance genes

Rv number

Gene function

Mechanism of drug resistance

Reference(s)

First-line agents

Rifamycins (for example, rifampicin)

rpoB

Rv0667

RNA polymerase

Target modification

[6]

ponA1

Rv0050

Probable bifunctional penicillin-binding protein

Unknown

[7]

Isoniazid

katG

Rv1908c

Catalase-peroxidase enzyme

Decreased drug activation

[8]

inhA

Rv1484

NADH-dependent enoyl-acyl carrier protein

Target amplification or modification

[9, 10]

Pyrazinamideb

pncA

Rv2043c

Pyrazinamidase

Decreased drug activation

[11, 12]

panD

Rv3601c

Aspartate decarboxylase

Unknown

[13]

rpsA

RRv1630

Ribosomal protein S1

Target modification

[14]

Ethambutolb

embCAB operon

Rv3793-5

Arabinosyltransferase

Target modification

[15, 16]

ubiA

Rv3806c

Arabinogalactan synthesis

Gain-of-function

[15]

Group A

Levofloxacin

Moxifloxacin

gyrA

Rv0006

DNA gyrase A

Target modification

[17, 18]

gyrB

Rv0005

DNA gyrase B

Target modification

[18]

Bedaquiline

atpE

Rv1305

ATP synthase

Target modification

[19]

pepQ

Rv2535c

Putative Xaa-Pro aminopeptidase

Unknown

[20]

Rv0678

Rv0678

Transcriptional regulator of mmpL5

Drug efflux

[21, 22]

Linezolid

Rrl

NA

23S rRNA

Target modification

[23]

rplC

Rv0701

50S ribosomal protein L3

Target modification

[24]

Group B

Clofazimine

pepQ

Rv2535c

Putative Xaa-Pro aminopeptidase

Drug efflux

[20]

Rv0678

Rv0678

Transcriptional regulator of mmpL5

Drug efflux

[21]

Cycloserine

Terizidone

Ald

Rv2780

L-alanine dehydrogenase

Substrate shunting

[25]

alr

Rv3423c

Alanine racemase

Target modification

[26, 27]

ddl

Rv2981c

D-alanine-D-alanine ligase

Target modification

[27]

cycA

Rv1704c

Bacterial D-serine/L-and D-alanine/glycine/D-cycloserine proton symporter

Mechanism not confirmed

[28]

Group C

Delamanid

Pretomanid

ddn

Rv3547

Oxidative stress

Decreased drug activation

[29]

fgd1

Rv0407

Glucose-6-phosphate oxidation

Decreased drug activation

[29]

Imipenem/cilastatin

crfA

Rv2421c-Rv2422 intergenic

Unknown

Drug inactivation

[30]

Amikacin, Capreomycin, Kanamycinc

Rrs

NA

16S rRNA

Target modification

[31]

Streptomycin

rpsL

Rv0682

12S ribosomal protein

Target modification

[32,33,34,35]

rrs

NA

16S rRNA

Target modification

[36]

gidB

Rv3919c

7-Methylguanosine methyltransferase

Target modification

[37]

Ethionamide Prothionamide

ethA

Rv3854c

Mono-oxygenase

Decreased drug activation

[38, 39]

ethR

Rv3855

Transcriptional regulatory repressor protein (TetR)

Decreased drug activation

[39]

inhA

Rv1484

NADH-dependent enoyl-acyl carrier protein

Target amplification or modification

[10]

Para-aminosalicylic acid (PAS)

folC

Rv2447c

Folate pathway

Decreased drug activation

[40]

dfrA

Rv2763c

Dihydrofolate reductase

Target amplification

[40]

thyA

Rv2764c

Thymidylate synthase

Target modification

[41, 42]

thyX

Rv2754c

Catalyzes dTMP and tetrahydrofolate

Mitigating target inhibition

[43]

ribD

Rv2671

Enzyme in riboflavin biosynthesis

Mitigating target inhibition

[40, 44]

Other medicinesc

Kanamycin

Eis

Rv2416c

Aminoglycoside acetyltransferase

Inactivating mutation

[45]

Capreomycin

tlyA

Rv1694

rRNA methyltransferase

Target modification

[46]

  1. Abbreviations: MDR-TB multidrug-resistant tuberculosis, NA not applicable, RR-TB rifampicin-resistant tuberculosis, WHO World Health Organization
  2. aAntitubercular drugs are listed by the 2018 WHO grouping of medicines recommended for use in longer, individualized MDR-TB regimens [47]. For each drug or drug class, the specific genes in which drug-resistance mutations are commonly identified are listed with their gene name, gene number (Rv number), gene function, and the confirmed or putative mechanisms of resistance. bPyrazinamide and ethambutol are first-line TB drugs that also are categorized as Group C medicines for the treatment of longer MDR-TB regimens. cKanamycin and capreomycin are no longer recommended to be included in longer, individualized MDR/RR-TB regimens