For subjects ultimately initiating TB treatment, the pharmacokinetic parameters to be tested against the MIC for each TB drug in the patient's regimen include peak (Cmax) and area under the concentration-time curve (AUC). Parameters will be compared to the expected ranges for each drug and expressed as both a population value and at the individual level (proportion of patients below the expected range for each drug). The clinical outcome of TB treatment failure will be compared to the proportion of subjects with a baseline (2 week) Cmax/MIC below the minimal target (lowest µg/ml concentration/ highest MIC of an isolate still considered susceptible) for 2 key drugs in the regimen. It is anticipated that TB treatment failure to be more frequent in subjects treated for drug-susceptible TB when Cmax/MIC values are lower than target for both rifampin and isoniazid, and in subjects treated for MDR-TB when values are below the minimal target for both ofloxacin and kanamycin. A binary logistic regression model will be used to determine the possible risk factors to TB treatment failure in addition to the pharmacokinetic parameters.