The upper respiratory infection is the most common illness seen by the practicing pediatrician. In dealing with these illnesses physicians often find it difficult to distinguish between bacterial and viral infections. The history, clinical findings, and an awareness of the illnesses in the community are sometimes sufficient to make this distinction possible. There nevertheless remains a significant number in whom the diagnosis is based on little more than a reasonable guess. Furthermore, if a bacterial etiology is suspected, it is only occasionally possible to recognize the pathogen from the clinical picture, and one resorts to chance in the selection of appropriate treatment.
During the past few years in an effort to treat infections less empirically, physicians have begun to incorporate bacteriologic methods as a part of their office laboratory. Initially our interest was concentrated on the identification of the β-hemolytic streptococcal infections. When cultures for this purpose proved useful, it