COMMON ETIOLOGIC AGENTS
Table 63 – 1 lists the more common causes of upper respiratory infections and stomatitis. Viral infections predominate. The most frequent bacterial cause to be considered is S. pyogenes. Corynebacterium diphtheriae, although rare in the United States, is a majorpathogen that continues to cause infection in many other countries and must not be over-looked, particularly if clinical and epidemiologic findings suggest this possibility. Neisseria gonorrhoeae, isolated from adults with symptomatic pharyngitis in whom noother etiologic agent can be demonstrated, is now considered a pharyngeal pathogen that is usually transmitted by oral – genital contact. Occasionally, other bacteria have been im-plicated as causes of acute pharyngitis (eg, Corynebacterium ulcerans, Arcanobacteriumhaemolyticum, Francisella tularensis, and streptococci of groups B, C, and G). These arelisted here for the sake of completeness but are not routinely sought except in unusual circumstances.
In patients with purulent rhinitis, sinusitis should also be considered in the differential diagnosis . Unilateral and foul-smelling purulent discharge suggests the presence of a foreign body in the nose.