<prompt> Optimal effective duration of short course therapy for pulmonary TB is:6 months9 months12 months18 months  <response>: Ans: a 6 months Ref: Park, 19th ed, p. 157Short course regimes of 6 months duration are highly effective, of low toxicity and well tolerated.These potent regimes are based on a initial intensive phase with four drugs--INH, rifampicin,Pyrizinamide, supplemented by either streptomycin or ethambutol for a period of 2 months, followed by 2 drugs in continuation phase.The treatment must be fully supervised and monitored mainly by bacteriological examination. 