New uses for older antibiotics - The 'rediscovery' of four beneficial and cost-effective antimicrobials

Because of its intracellular mechanism of activity, excellent safety profile, and low cost, doxycycline is one of the most extensively used antibiotics in the. world, and its use will increase as new applications are found. One of its most important uses is in treatment of bacterial community-acquired pneumonias, but it is also useful against atypical pneumonias and sexually transmitted disease. As zoonotic infections continue to increase around the world, doxycycline will occupy an increasingly prominent place. Minocycline shares doxycycline's favorable attributes and also has tissue-penetration characteristics that are important when therapeutic alternatives are few, as in MRSA. TMP-SMX is widely used to treat urinary and respiratory tract infections and for prophylaxis and treatment of P carinii infection. As the AIDS epidemic continues, its use will continue to grow, because it is also effective against other pathogens associated with AIDS. TMP-SMX is relatively underused for treating gram-negative bacteremias, especially nosocomial infections caused by nonaeruginosa pseudomonads. Metronidazole is a cost-effective antianaerobic component in treatment of intra-abdominal and pelvic infections, especially when it is combined with a once-a-day antibiotic.