Question
A 30-year-old male patient with history of productive cough, evening rise of temperature and weight loss since 1 month visits a physician in a tertiary care hospital. On investigation, patient was positive for acid fast bacilli in the sputum and a diagnosis of pulmonary tuberculosis was made. (
- (a) Enumerate the drugs used for the above condition. Discuss the regimen for this patient ( 4 mark(s)
- (b) Add a note on the management of Multi Drug Resistant Tuberculosis. ( 3 mark(s)
- (c) Mention the benefits of combination of Antitubercular drugs 4 mark(s)
Answer
a) Drugs used and regimen for this patient First-line drugs: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol, Streptomycin. This patient, newly diagnosed with sputum-positive pulmonary tuberculosis, is started on the standard two-phase regimen: intensive phase (2 months) with four drugs — Isoniazid, Rifampicin, Pyrazinamide, Ethambutol — targeting the large, actively multiplying bacterial population; followed by the continuation phase (4 months) with Isoniazid and Rifampicin alone, to sterilize slower-growing/persister organisms and prevent relapse.
b) Management of MDR-TB MDR-TB (resistant to at least isoniazid and rifampicin) requires a longer, more toxic second-line regimen: a combination of fluoroquinolones (levofloxacin, moxifloxacin), second-line injectables (kanamycin, amikacin — increasingly replaced by newer oral agents), and other second-line drugs (ethionamide, cycloserine, PAS), often supplemented by newer agents (bedaquiline, linezolid). Treatment duration is substantially longer (18-24 months historically, shorter regimens now available), with poorer outcomes and greater toxicity than standard first-line therapy — directly reflecting the resistance-prevention logic of standard therapy failing.
c) Benefits of combining antitubercular drugs
- Prevents emergence of drug resistance — the probability of a bacterium being spontaneously resistant to two or more unrelated drugs simultaneously is vanishingly small, so combination therapy prevents selection of resistant mutants that monotherapy would allow to emerge.
- Increases bactericidal efficacy — different drugs act on different bacterial subpopulations (actively dividing, semi-dormant, intracellular acidic environment), so combining them achieves more complete kill than any single agent.
- Allows shorter, more effective overall treatment — by attacking multiple targets/subpopulations simultaneously rather than sequentially.
- Reduces relapse risk — more complete eradication of persister organisms reduces the chance of disease recurrence after treatment completion.