Bactrim consists of two medications: sulfamethoxazole and trimethoprim. The first inhibits synthesis of dihydrofolic acid (the substance important for human and bacterial metabolism) while the last blocks next stage of its biochemical cycle: formation of tetrahydrofolic acid which occurs only in microorganisms. This medication is effective against streptococci, staphylococci, pneumococci, bacillus dysentery, typhoid fever, E. coli, Proteus, and ineffective against Mycobacterium tuberculosis, spirochetes, Pseudomonas aeruginosa. Bactrim is applied in treatment of pneumonia and other diseases of respiratory, gastrointestinal systems, urogenital systems caused by bacterial infections which develop after surgery and others.