Pharmacokinetic and Safety Trial to Determine the Appropriate Dose for Pediatric Patients With Multidrug Resistant Tuberculosis

Inclusion Criteria: * Confirmed diagnosis of MDR-TB OR * Presumptive diagnosis of MDR-TB including one of the following: * Clinical specimen suggestive of TB * Persistent cough lasting \> 2 weeks * Fever, weight loss, and failure to thrive * Findings on recent chest radiograph (prior to Visit 1) consistent with TB AND * Household contact of a person with known MDR-TB or a person who died while appropriately taking drugs for sensitive TB OR * On first-line TB treatment but with no clinical improvement * Negative urine pregnancy test for female patients who have reached menarche * Written informed consent/assent Exclusion Criteria: * Laboratory evidence of active hepatitis B or C * Children with body weight \< 5.5 kg * For patients with HIV co-infection, CD4 cell count ≤ 1000/mm3 for children 1-5 years old, and ≤ 1500/mm3 for children less than 1 year old * History of allergy to metronidazole and any disease or condition in which metronidazole is required * Use of amiodarone within 12 months or use of other predefined antiarrhythmic medications within 30 days prior to first dose of delamanid * Serious concomitant conditions * Preexisting cardiac conditions * Abnormalities in Screening ECG (including AV block, BBB or hemi-block, QRS prolongation \> 120 msec, or QTcF \> 450 msec in both males and females) * Concomitant condition such as renal impairment characterized by serum creatinine levels \>1.5 mg/dL, hepatic impairment (ALT or AST \> 3x ULN), or hyperbilirubinemia characterized by total bilirubin \> 2x ULN * Current diagnosis of severe malnutrition or kwashiorkor * Positive urine drug screen (Groups 1 and 2 only) * Rifampicin and/or moxifloxacin within 1 week prior to the first dose of delamanid and/or any prior or concurrent use of bedaquiline * Lansky Play Performance Score \< 50 (not applicable for children \< 1 year old) or Karnofsky Score \< 50 * Administered an IMP within 1 month prior to Visit 1 * Pregnant, breast-feeding, or planning to conceive or father a child within the timeframe described in the information consent form (Groups 1 and 2 only)