Potential importance of Legionella species as etiologies in community acquired pneumonia (CAP)

Large percentages of patients with community acquired pneumonia (CAP) do no t have a defined etiology. Between 1992-1993, 99 acute and convalescent ser a were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against th e following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, w as seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. ly ticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted t o several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism ide ntified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionel la isolates other than L. pneumophila serogroup 1 need to be developed. (C) 2000 Elsevier Science Inc. All lights reserved.