Quantitative Drug-Susceptibility in Patients Treated for Multidrug-Resistant Tuberculosis in Bangladesh: Implications for Regimen Choice: e0116795

Background Multidrug-resistant tuberculosis (MDR-TB) treatment in Bangladesh is empiric or based on qualitative drug-susceptibility testing (DST) by comparative growth in culture media with and without a single drug concentration. Methods Adult patients were enrolled throughout Bangladesh during the period of 2011-2013 at MDR-TB treatment initiation. Quantitative DST by minimum inhibitory concentration (MIC) testing for 12 first and second-line anti-TB drugs was compared to pretreatment clinical characteristics and treatment outcomes. MIC values at or one dilution lower than the resistance breakpoint used for qualitative DST were categorized as borderline susceptible, and MIC values one or two dilutions greater as borderline resistant. Results Seventy-four patients were enrolled with a mean age of 35 plus or minus 15 years, and 51 (69%) were men. Of the rifampin isolates with MIC >1.0 mu g/ml, 12 (19%) were fully susceptible or borderline susceptible to rifabutin (MIC less than or equal to 0.5 mu g/ml). Amikacin was fully susceptible in 73 isolates (99%), but kanamycin in only 54 (75%) (p