Antibiotics--past, present, and future.

The drug therapy for diseases other than those caused by microbial agents involves treating the host. In infectious diseases therapy, the goal is to rid the host of the pathogen. Hence, drug therapy is aimed at the pathogen. Because a second living agent is involved in the triangle, drug therapy is affected by the pathogen's nature, its tissue specificity, and, most importantly, the changes it undergoes to survive. The history of antimicrobial therapy has clearly demonstrated that the drugs that are used to treat infections are also responsible for making them more difficult to treat in future. The only way to keep antimicrobial agents useful is to use them appropriately and judiciously.