Resistance in regimen

If resistance to INH is higher than 4%, the initial drug regimen should include ethambutol or streptomycin. Tuberculosis resistant only to INH (the most common form of resistance) can be treated for 6 month with a regimen of rifampin + pyrazinamide + ethambutol or streptomycin. Multidrug-resistant organisms (resistant to both INH and rifampin) should be treated with 3 or more drugs to which the organism is susceptible for a period of more than 18 month, including 12 mo after sputum cultures become negative.