Multidrug-resistant (MDR) TB: is defined as resistance to both H and R and may be any number of other(1ST LINE) anti-TB drugs. MDR-TB has a more rapid course (some die in 4-16 weeks). Treatment of these cases is difficult, because one or more second line drugs are to be given for 12-24 months. If sensitivity of the TB bacilli is known, the drug/ drugs to which they are resistant is /are excluded and other first line drugs are prescribed along with 1-3 second line drugs. A total of 5-6 drugs are given. One of the FQs is generally included. ln case streptomycin is not being given, one out of kanamycin/ amikacin/ capreomycin should be added, because they are tuberculocidal. TOBRAMYCIN It was obtained from S. tenebrarius in the 1970s. The antibacterial and pharmacokinetic propeies, as well as dosage are almost identical to gentamicin, but it is 2-4 times more active against Pseudomonas and Proteus, including those resistant to gentamicin. However, it is not useful for combining with penicillin in the treatment oi enterococcal endocarditis. It should be used only as a reserve alternative to gentamicin. Serious infections caused by Pseudomonas and Proteus are its major indications. Ototoxicity and nephro toxicity is probably lower than gentamicin. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:724,748