With the advent of additional antibiotics, a wider choice of agents is available, and many more species of micro-organisms are now susceptible to chemotherapy. These newer antibiotics do not lessen the need for definitive diagnosis. If anything, it is even more important to establish the precise indications for these agents and diminish their indiscriminate use. Our objective in chemotherapy is to choose the agent or agents that will be most effective, least likely to produce side-reactions, and most economical to the patient. During the years since the first antibiotics became available, the following developments have necessitated a reconsideration of therapy and indicated that these agents are not an unmixed blessing.
For example, resistance has emerged in certain bacteria not only to one antibiotic but simultaneously to several.1 It should be emphasized, and it is indeed fortunate, that to date the pneumococci and group A beta hemolytic streptococci, the organisms