The upper respiratory tract extends from the larynx to the nostrils and comprises the oropharynx and the nasopharynx together with the communicating cavities, the sinuses and the middle ear. The upper respiratory tract can be the site or several types of infection:
• pharyngitis, sometimes involving tonsillitis, and giving rise to a “sore throat”,
• otitis media,
Of all those infections, pharyngitis is by far the most frequent; in addition, the untreated infection may have serious sequelae. Only pharyngitis will be considered here.
Most cases of pharyngitis have a viral etiology and follow a self-limiting course. However, approximately 20% are caused by bacteria and usually require treatment with appropriate antibiotics. As the physician is rarely able to make a distinction between viral and bacterial pharyngitis on clinical grounds alone, treatment should ideally be based on the result of bacteriological examination.
Bacteriological diagnosis of pharyngitis is complicated by the fact that the oropharynx contains a heavy mixed normal flora of aerobic and anaerobic bacteria. The normal flora generally outnumbers the pathogens and the role of the bacteriologist is to distinguish between the commensals and the pathogens. Where possible only the latter should be reported to the physician.