title: Pneumococcal pneumonia diagnosis by demonstration of pneumolysin antibodies in precipitated immune complexes: a study in 350 Philippine children with acute lower respiratory infection.
abstract: In searching for suitable methods for aetiological diagnosis of pneumococcal disease we determined capsular polysaccharide, C-polysaccharide and pneumolysin antibodies bound in immune complexes (IC) in Filipino children. Sera were obtained from 150 healthy infants (all under 12 months old) and from 350 paediatric patients (mean age 18 months) hospitalized with severe pneumonia. The findings in healthy children were not associated with age, sex or pneumococcal carrier status; 3-7% exceeded the cut-off limits for positivity in different antibody assays. By contrast, 97 (51%) of the 190 patients with a complete 3-sample series exceeded the cut-off limit for IC-bound pneumolysin-IgG in at least 1 of the serum samples studied. Positivity rates for IC-bound pneumolysin-IgG in the admission day, in-patient and convalescent sample of the 350 patients were 25%, 25% and 34%. Pneumolysin-IgM, capsular polysaccharide and C-polysaccharide antibodies in the IC were positive in only 4-6% of the patients' samples. IC-bound pneumolysin-IgG antibody assay seem to be a useful method for species-specific diagnosis of pneumococcal infections.
authors.affiliation: Department in Oulu, National Public Health Institute, Helsinki, Finland.
authors.forename: K S
authors.initials: KS
authors.lastname: Lankinen
authors.forename: P
authors.initials: P
authors.lastname: Ruutu
authors.forename: H
authors.initials: H
authors.lastname: Nohynek
authors.forename: M
authors.initials: M
authors.lastname: Lucero
authors.forename: J C
authors.initials: JC
authors.lastname: Paton
authors.forename: M
authors.initials: M
authors.lastname: Leinonen
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology*; D001426:Bacterial Proteins; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D010679:Philippines; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis* / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000276:immunology; D011446:Prospective Studies; D015203:Reproducibility of Results; D013296:Streptococcus pneumoniae / Q000276:immunology*; D013301:Streptolysins / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000936:Antigen-Antibody Complex; D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; C027158:polysaccharide C-substance (Streptococcus)