Patient description: Patient A is a 30-year-old male who was admitted to the hospital after 10 days of cough, profuse nocturnal sweating and loss of appetite. He had traveled to India 1 months ago and has not any positive history of TB vaccination. He is a previously healthy man, working as an engineer in a high tech company. He doesn't smoke o use any illicit drugs. He was febrile (38 c) with heart rate of 115 b/min, respiratory rate of 22, BP of 125/75 mmHg and O2 sat of 97%. Chest X-ray showed infiltrate in the middle of left lung with diameter of 1.8 cm with signs of cavitation. The sputum smear revealed positive sputum culture for Mycobacterium tuberculosis which are sensitive of the first-line TB drugs (isoniazid, streptomycin, rifampicin and ethambutol). Lab study is reported bellow: Hgb: 13 g/dl WBC: 14000 /mm3 Plt: 300000 /ml AST: 13 U/L ALT: 15 U/L Alk P: 53 U/L Bill total: 0.6 mg/dl Na: 137 mEq/l K: 4 mEq/l Creatinine: 0.5 mg/dl BUN: 10 mg/dl ESR: 120 mm/hr

Clinical trial eligibility criteria: eligible ages (years): 18.0-75.0,  Pulmonary Tuberculosis Subjects are required to meet all of the following in order to be randomized. 1. Provide written, informed consent prior to all trial-related procedures. 2. Male or female, aged between 18 and 75 years inclusive. 3. Body weight (in light clothing and with no shoes) between 35 and 100 kg, inclusive. 4. Drug-sensitive pulmonary Tuberculosis (TB) determined by testing at the trial appointed laboratory: M.tb positive and rifampicin sensitive on molecular test (e.g. GeneXpert or Hain) and sputum smear-positive pulmonary TB on direct microscopy for acid-fast bacilli (at least 1+ on the scale). 1. either newly diagnosed OR 2. untreated for at least 3 years after cure from a previous episode (Subject can give a history of cure and previous treatment); AND 3. Previous TB treatment must be discontinued as per  5. A chest X-Ray which in the opinion of the Investigator is consistent with TB. 6. Ability to produce an adequate volume of sputum as estimated from a screening Coached Spot Sputum Sample assessment (estimated 10 ml or more overnight production). 7. Be of non-childbearing potential or using effective methods of birth control, as defined below: Non-childbearing potential: 1. Subject not heterosexually active or practices sexual abstinence; OR 2. Female Subject/sexual partner bilateral oophorectomy, bilateral tubal ligation and/or hysterectomy or has been postmenopausal with a history of no menses for at least 12 consecutive months; OR 3. Male Subject/sexual partner vasectomised or has had a bilateral orchidectomy minimally three months prior to screening; Effective birth control methods: A double contraceptive method should be used as follows: 1. Double barrier method which can any 2 of the following: a male condom, diaphragm, cervical cap, or female condom (male and female condoms should not be used together); OR 2. Barrier method (one of the above) combined with hormone-based contraceptives or an intra-uterine device for the female Subject/partner; AND 3. Are willing to continue practicing one of the above mentioned birth control methods throughout treatment and for 1 month (both male and female Subjects) after the last dose of study medication or discontinuation from study medication in case of premature discontinuation Subjects will be excluded from participation if they meet any of the following criteria. Medical 1. Evidence of clinically significant (as judged by the Investigator), metabolic, gastrointestinal, cardiovascular, musculoskeletal, ophthalmological, pulmonary, neurological, psychiatric or endocrine diseases, malignancy, or other abnormalities (other than the indication being studied) including malaria. A rapid test for malaria may be carried out if indicated. 2. Poor general condition where any delay in treatment cannot be tolerated per discretion of the Investigator. 3. Clinically significant evidence of extrathoracic TB (e.g. miliary TB, abdominal TB, urogenital TB, osteoarthritic TB, TB meningitis), as judged by the Investigator. 4. History of allergy or hypersensitivity to any of the study Investigational Medicinal Products or related substances. 5. Known or suspected current alcohol and/or drug abuse (positive urine drug screen) or history thereof within the past 2 years that is, in the opinion of the Investigator, sufficient to compromise the safety and/or cooperation of the Subject. 6. A history of seizures or risk factors for seizures. 7. For HIV infected Subjects: 1. having a CD4+ count <250 cells/μL; 2. with an AIDS-defining opportunistic infection or malignancies (except pulmonary TB); 3. OR having received antiretroviral therapy medication within the last 90 days 4. OR having received oral or intravenous antifungal medication within the last 90 days. 8. Having participated in other clinical study/ies with investigational agent/s within 8 weeks prior to trial start. 9. Significant cardiac arrhythmia requiring medication or QT interval on ECG >500msec on screening ECG. 10. Subjects with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis 11. Females who are pregnant or breast-feeding, or planning to conceive a child during the study or within 1 month of cessation of treatment 12. Diabetes Mellitus Specific Treatments 13. Previously received treatment with linezolid. 14. Known allergy or intolerance to linezolid. 15. Concomitant use of monoamine oxidase inhibitors (MAOIs) or prior use within 1 month of screening. 16. Concomitant use of serotonergic agents including SSRI/SNRI antidepressants or prior use within 3 days of screening should be avoided if possible as subjects on these agents and linezolid are at risk for serotonin syndrome. 17. Treatment with any drug active against M.tb within 3 months prior to Day 1 (including but not limited to isoniazid, ethambutol, amikacin, bedaquiline, clofazimine, cycloserine, fluoroquinolones, rifabutin, rifampicin, streptomycin, kanamycin, para-aminosalicylic acid, rifapentine, pyrazinamide, thioacetazone, capreomycin, thioamides, metronidazole). Based on Laboratory Abnormalities: 18. Subjects with the following toxicities at screening as defined by the enhanced Division of Microbiology and Infectious Disease (DMID) adult toxicity table (November 2007): 1. creatinine grade 2 or greater [>1.5 x Upper Limit of Normal (ULN)]; 2. hemoglobin level of <8.0 gm/dL; 3. platelet count <80,000/mm3; 4. absolute neutrophil count <1000/mm3 5. serum potassium, serum magnesium and calcium (corrected for albumin) levels less than the lower limit of normal for the laboratory; 6. aspartate aminotransferase (AST) grade 3 or greater (≥3.0 x ULN) to be excluded; 7. alanine aminotransferase (ALT) grade 3 or greater (≥3.0 x ULN) to be excluded; 8. alkaline phosphatase (ALP) grade 4 (>8.0 x ULN) to be excluded, grade 3 (≥3.0 - 8.0 x ULN) must be discussed with and approved by the Sponsor Medical Monitor; 9. total bilirubin grade 3 or greater (≥2.0 x ULN, or ≥1.50 x ULN when accompanied by any increase in other liver function test) to be excluded, grade 2 (≥1.50 x ULN, or ≥1.25 x ULN when accompanied by any increase in other liver function test) must be discussed with and approved by the Sponsor Medical Monitor; Any laboratory value which excludes the Subject may be repeated to confirm eligibility. All and no must be met. If no single variable/value is outside of the ranges of acceptability, but when multiple values are close to the limits and/or whenever the Investigator has reason to suspect that there might be a health problem (other than TB), enrollment should only be considered after discussing the case with the sponsor medical monitor