New uses of older antibiotics

Many of the older antibiotics, such as second generation tetracyclines doxycycline and minocycline, trimethoprim-sulfamethoxatehoxazole, clindamycin, and metronidazole, are active against a number of newly described infectious diseases. Older agents are well absorbed orally, attain excellent tissue penetration, and are available in generic form, which reduces their cost. A number of resistant bacteria, such as MRSA, MRSE, and some VRE, are sensitive to minocycline and doxycycline. TMP-SMX has activity against Isospora belli, Cyclospora, Pneumocystis carinii, and Toxoplasma. Clindamycin, with its anaerobic activity, combined with a quinolone, provides excellent coverage for diabetic foot infections, polymicrobial osteomyelitis, and infected decubitus ulcers.