Clinical aspects on bacterial infections in the upper respiratory tract.

Acute respiratory tract infections represent the major cause of morbidity in younger age groups. Most of these infections involve the upper respiratory tract. The frequency of respiratory tract infections vary not only with age, but also with season of the year and the epidemiological situation. Surveys of the incidence and aetiology of these infections must therefore cover large populations during relatively long periods of time. In the developed countries, the mortality in respiratory tract infections in patients below the age of 60 years is low, while it increases markedly in elderly patients, mainly due to involvement of the lower respiratory tract. Aetiologically, viral infections dominate but bacterial pathogens often cause pharyngitis/tonsillitis, otitis media and sinusitis. In longstanding cough in children, Branhamella catarrhalis has been found to be a pathogen of probably high significance. Other factors increasing the clinical importance of colonisation of the upper respiratory tract with potentially pathogenic bacterial species, are various immune defects, especially reduced IgA production, and granulocytopenia. In the latter case, Gram-negative bacteria seem to be more pathogenic than Gram-positive ones. The clinical differentiation between viral and bacterial upper respiratory tract infections is difficult and sometimes not possible. However, based on the knowledge that acute tracheitis, laryngitis and common cold are normally caused by viral agents, it seems reasonable not to use antibiotics for those patients.