Correction to: Eur J Med Res (2019) 24:38 https://doi.org/10.1186/s40001-019-0397-2

The original publication of this article [1] contained few erroneous paragraphs and errors in Table 1 and Table 2. The first four paragraphs are in the ‘Results’ section while the last four paragraphs are in the ‘Discussion’ section. The errors in Table 1 involve the number of isolates tested for pyrazinamide and pyrazinamide susceptible isolates, ethambutol-susceptible isolates with a mutation and number of resistant isolates with a mutation for streptomycin. The error in Table 2 involves wrong codon number for a mutation in isolate KM17-01 in Cluster XII for gidB gene. The updated informations have been indicated in bold and also refer corrected Tables 1 and 2.

Table 1 Phenotypic resistance by MGIT 960 system to anti-TB drugs among 93 multidrug-resistant M. tuberculosis isolates and number of susceptible and resistant isolates with mutations in target genes for each drug
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Table 2 Detailed clinical, demographic and molecular characteristics of 42 M. tuberculosis isolates in 16 (Cluster I to Cluster XVI) clusters
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Incorrect: Although all 93 MDR-TB isolates were tested for susceptibility to pyrazinamide, only 47 isolates yielded interpretable results; 11 isolates were susceptible and 36 were resistant to this drug including 15 isolates that were resistant to all five drugs. The remaining 46 MDR-TB strains failed to grow at the reduced pH in the absence of the drug.

Correct: Although all 93 MDR-TB isolates were tested for susceptibility to pyrazinamide, only 46 isolates yielded interpretable results; 10 isolates were susceptible and 36 were resistant to this drug including 15 isolates that were resistant to all five drugs. The remaining 47 MDR-TB strains failed to grow at the reduced pH in the absence of the drug.

Incorrect: The proportion of MDR-TB isolates exhibiting resistance conferring mutations in target genes varied for different anti-TB drugs, being highest for rifampicin and lowest for streptomycin (Table 1).

Correct: The proportion of MDR-TB isolates exhibiting resistance conferring mutations in target genes varied for different anti-TB drugs, being highest for rifampicin and lowest for streptomycin among SIRE drugs (Table 1).

Incorrect: PCR-sequencing of pncA identified mutations in 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 46 isolates for which phenotypic DST data for pyrazinamide was not available while all 11 isolates phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Correct: PCR-sequencing of pncA identified mutations in 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 47 isolates for which phenotypic DST data for pyrazinamide was not available while all 10 isolates phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Incorrect: Fifty isolates contained mutations at embB306 (M306V, n = 28; M306I, n = 19 and M306L, n = 3), 15 isolates contained a mutated embB406 (G406D, n = 8; G406A, n = 4; G406C, n = 2 and G406S, n = 1), 10 isolates contained a mutated embB497 (Q497R, n = 6; Q497K, n = 3 and Q497H, n = 1) and one isolate contained a mutation (Y319S) at embB319.

Correct: Fifty isolates contained mutations at embB306 (M306V, n = 28; M306I, n = 19 and M306L, n = 3), 16 isolates contained a mutated embB406 (G406D, n = 8; G406A, n = 5; G406C, n = 2 and G406S, n = 1), 10 isolates contained a mutated embB497 (Q497R, n = 6; Q497K, n = 3 and Q497H, n = 1) and one isolate contained a mutation (Y319S) at embB319.

Incorrect: Forty-nine of 59 MDR-TB strains additionally resistant to streptomycin contained a mutation in the target genes analysed (Table 1), many of which have been described previously [23, 28]. These included 44 isolates with a mutation in rpsL (K43R, n = 33; K43T, n = 1; K88R, n = 5; K88T, n = 4; K88M, n = 1), four isolates with a mutation in rrs 500 or 900 region (A514C, n = 1; C517T, n = 1; G878A, n = 1 and A906G, n = 1) and one isolate with rpsL K88R + rrs C602A double mutation.

Correct: Fifty-one of 59 MDR-TB strains additionally resistant to streptomycin contained a mutation in the target genes analysed (Table 1), many of which have been described previously [23, 28]. These included 44 isolates with a mutation in rpsL (K43R, n = 33; K43T, n = 1; K88R, n = 5; K88T, n = 4; K88M, n = 1), four isolates with a mutation in rrs 500 or 900 region (A514C, n = 1; C517T, n = 1; G878A, n = 1 and A906G, n = 1) and three isolates with double mutation inrpsLandrrsgenes (rpsLK43R + rrsC527T, n = 1;rpsLK88T + rrsC517T, n = 1;rpsLK88R + rrsC602A, n = 1).

Incorrect: Resistance conferring mutations in rpsL and/or rrs gene were detected in majority (49 of 59, 83%) of streptomycin-resistant but not in any streptomycin-susceptible MDR-TB strain while mutations in embB gene were detected in both ethambutol-resistant and -susceptible MDR-TB strains, as described in our previous studies [23, 28].

Correct: Resistance conferring mutations in rpsL and/or rrs gene were detected in majority (51 of 59, 86.4%) of streptomycin-resistant but not in any streptomycin-susceptible MDR-TB strain while mutations in embB gene were detected in both ethambutol-resistant and -susceptible MDR-TB strains, as described in our previous studies [23, 28].

Incorrect: Phenotypic DST results for pyrazinamide were available for only 47 of 93 MDR-TB strains while the remaining 46 isolates failed to grow at lower pH. No pncA mutation was detected in 50 pansusceptible strains. Analysis of 93 MDR-TB strains showed that 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 46 isolates for which DST data for pyrazinamide was not available contained a mutation in pncA while all 11 MDR-TB strains phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Correct: Phenotypic DST results for pyrazinamide were available for only 46 of 93 MDR-TB strains while the remaining 47 isolates failed to grow at lower pH. No pncA mutation was detected in 50 pansusceptible strains. Analysis of 93 MDR-TB strains showed that 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 47 isolates for which DST data for pyrazinamide was not available contained a mutation in pncA while all 10 MDR-TB strains phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Incorrect: The two isolates in Cluster XII were also very closely related, with the second isolate (KM17-01) displaying an additional mutation (L95F) in gidB which is considered as a hot-spot for mutations in the M. tuberculosis genome [21, 57].

Correct: The two isolates in Cluster XII were also very closely related, with the second isolate (KM17-01) (Table 2) displaying an additional mutation (L59F) in gidB which is considered as a hot-spot for mutations in the M. tuberculosis genome [21, 57].