Table 1.

Sequence analysis of the rpoB gene of M. tuberculosis isolates from a region in Northern Italy

RMP phenotypeAffected codon(s) (mutation)aAmino acid change(s)No. of isolatesNo. of individual strains (frequency [%])
Resistantb533 (CCG)Leu→Pro11 
Resistant531 (TTG)Ser→Leu4335 (57.4)
Resistant531 (TGG)Ser→Trp11 
Resistant526 (GAC)His→Asp144 (6.6)
Resistant526 (TAC)His→Tyr76 (9.8)
Resistant526 (CTC)His→Leu11 
Resistant526 (AAC)His→Asn11 
Resistantc522 (CAG)Ser→Gln11 
Resistant516 (TAC)Asp→Tyr65 (8.2)
Resistant516 (GGC)Asp→Gly11 
Resistant516 (GTC)Asp→Val22 
Resistantd512 (ACC), 526 (AAC)Ser→Thr, His→Asn11 
Resistante513 (GAA), 562 (GCA)Gln→Glu, Glu→Ala11 
Resistant510–513 deletion (GCTGAGCCA)Leu-Ser-Gln deletion11 
SusceptibleNoneNone3632 
Total11793 
  • a Numbers correspond to E. coli numbering system for the RNA polymerase β-subunit. Nucleotide substitutions are underlined.

  • b Resistant to RMP at 2 μg/ml by the BACTEC method.

  • c Two mutations in the same codon.

  • d Two mutations in separate codons.

  • e Two mutations in separate codons, one of which is located outside the rpoB core region.