Much has been written recently concerning the new and growing occurrence of infections in compromised hosts. During the almost four decades since the end of World War II scientific investigation has produced extraordinary advances in diagnosis and treatment. This has resulted in two changes which have implications for this discussion. First, the classical acute community-acquired infections now are recognized quickly and treated effectively with antibiotics. Indeed, many such infections are managed quite effectively by physicians in the office or clinic and no longer require admission to the hospital. (For example, it has been years since I have seen mastoiditis or streptococcal erysipelas in my hospital consulting practice.) We have abandoned our “pneumonia ward” which once housed patients in various stages of life-threatening pneumococcal infection. Similarly, intensive immunization of our population has virtually eliminated poliomyelitis, diphtheria, tetanus, and measles; once common, these classical infectious diseases now are absent from our hospital.

The second effect of medical progress has been the opportunity to offer patients with certain diseases, previously untreatable, the hope of increased survival and even cure. The list here is long and includes premature infants, children with congenital immune deficiency disorders, individuals with leukemia, lymphoma, aplastic anemia, burns, renal and other organ failure, and many others. Thus, the numbers of such patients in our hospitals have increased. These patients are at an increased risk of acquiring a complicating infection because of their underlying disease or because of our diagnostic and therapeutic interventions.