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Table 3 Molecular targets of resistance distributed by Bactec MGIT result or category of minimum inhibitory concentration (MIC) (N = 13 isolates)

From: Application of quantitative second-line drug susceptibility testing at a multidrug-resistant tuberculosis hospital in Tanzania

Drug; gene MGIT MGIT MIC MIC MIC
Susceptible Resistant Susceptible Borderline Resistant
susceptible
Rifampin; rpoB      
wildtype 5 0 4 N/A 1
mutation 0 8 0 N/A 8
Isoniazid; inhA or katG      
wildtype 4 0 2 N/A 1
mutation 0 9 0 N/A 10
Ethambutol; embB      
wildtype 6 1 2 4 1
mutation 6 0 1 3 2
Ofloxacin; gyrA      
wildtype/silent mutation N/A N/A 6 7 N/A
mutation N/A N/A 0 0 N/A
Amikacin; rrs or eis      
wildtype N/A N/A 8 4 1
mutation N/A N/A 0 0 0
Ethionamide; inhA      
wildtype N/A N/A 5 7 1
mutation N/A N/A 0 0 0
  1. embB mutation included: Glu378Ala in 2 isolates; Met306Val, Met306Ile, Gly406Asp, Gly406Cys, Tyr319Cys in single isolates. Pyrazinamide susceptibility was not performed but pncA mutations included: Val128Gly in 2 isolates; Glu111stop, Asp49Gly, Ser179Ile, and Val169Ala in single isolates. Val128Gly and Val169Ala have not previously been reported. Five isolates (63%) resistant to both isoniazid and rifampin had pncA mutation.