[Respiratory tract infections caused by Haemophilus influenzae in adults]

Pneumonia counts as one of the most frequent severe Haemophilus influenzae infections to afflict adults. 60% of patients with pneumonia caused by type b H. influenzae are more than 50 years old, 30% to 40% are alcoholics, and 30% to 40% have chronic pulmonary disease or other concurrent illness. In the majority of cases there is multilobular, maculate, diffuse and usually bilateral involvement of the pulmonary tissue. The mortality rate due to type b H. influenzae pneumonia ranges between 30% and 40%. In patients with non-bacteriaemic pneumonia caused by non-encapsulated strains of H. influenzae it is rare for several lobes to be involved, there is little exudation and the mortality rate is low. H. influenzae is a significant pathogen in acute epiglottitis in adults and it also appears to play an important role in acute exacerbations of chronic obstructive lung disease (COLD) and acute sinusitis. beta-lactamase production mediated by R-factors or plasmids of gram-negative bacteria is responsible for ampicillin resistance. In 1978 the overall rate of resistance of H. influenzae to ampicillin in American hospitals amounted to 18%. H. influenzae are found in the nasopharynx of people exposed to others infected with H. influenzae. The risk of secondary infection in children who come into contact with patients infected with type b H. influenzae amounts to approximately 2.1%. Adults in close contact with children suffering from severe H. influenzae infections must be warned of the possible risks of secondary infection.