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Table 2 Classification of isolates of Tuberculosis Regional Reference Laboratory in Mashhad (n = 123) based on antibiotic susceptibility testing and distribution of gyrA and gyrB genes mutation patterns

From: Genotypic and phenotypic characterization of Mycobacterium tuberculosis resistance against fluoroquinolones in the northeast of Iran

Gene Nucleotide change Amino acid change Clinical isolates (n = 111) MDR-TB
(n = 12)
Polydrug resistant
(n = 0)
(n = 108)
FQ mono-resistant
(n = 3)a
gyrA C(269) → T Ala(90) → Val
T(271) → C Ser (91) → Pro
A(281) → G Asp(94) → Gly 1 (new case) 2 (XDR)b
Phenotypically FQ resistant, without any gyrase mutations 2 (1 new, 1 relapse) 1
All phenotypically FQ resistant 3 3c
  1. Note: Pansusceptible: susceptible to all first-line anti-TB drugs, FQ mono resistance: being resistant only to FQ, but sensitive to all first-line TB drugs, MDR-TB: resistance to at least both isoniazid and rifampin, Polydrug resistance: resistance to more than one first-line anti-TB drug, other than both isoniazid and rifampin
  2. aThese three isolates were all related to Iranian patients. Two of them were new TB cases and one was a TB relapse
  3. bThese two MDR isolates were resistant to FQs and also they were found to be resistant against kanamycin and amikacin in another study by our colleagues on these isolates [30]. Both were TB treatment failure cases, one from Afghanistan and one from Kazakhstan
  4. cAll were treatment failure cases