The association of bacteremic Haemophilus influenzae pneumonia in adults with typable strains

Analysis of the data accumulated indicates that bacteremic H. influenzae pneumonia is almost invariably associated with typable strains and with lobular or segmental lung involvement, especially on the right side, and the role of unencapsulated and hence nontypable strains in pneumonia remains uncertain.

Abstract

Seven cases of Haemophilus influenzae pneumonia in adults are presented, and twenty-two cases recorded in the literature are reviewed. Because the relevance of H. influenzae recovered from sputum culture is uncertain, patients qualified for the series by meeting the diagnostic criteria of roentgenographic evidence of pneumonia together with recovery of the organism from the blood, pleural fluid and/or lung tissue. Consequently, this report studies essentially the bacteremic form of H. influenzae pneumonia. Analysis of the data accumulated indicates that bacteremic H. influenzae pneumonia is almost invariably (twenty-five of twenty-six cases) associated with typable strains (mainly type B) and with lobular or segmental lung involvement, especially on the right side. The role of unencapsulated and hence nontypable strains in pneumonia remains uncertain but, if they are a source of pneumonia, it is suggested that they are rarely invasive. The study also suggests that the routine typing of haemophili recovered from blood and sputum in conjunction with the x-ray findings may be of value in determining whether one is dealing with colonization or actual respiratory infection.