Serological evidence for a causative role of non-group A hemolytic streptococci in pharyngitis.

Non-group A beta-hemolytic streptococci were isolated from the throats of 30 adult patients with symptoms of pharyngitis. Grouping by counterimmunoelectrophoresis identified 7 strains belonging to group B, 5 to group C, 8 to group G, 1 to group K; 9 were no groupable. Convalescent sera were available from 17 patients and were assayed for antibody to streptolysin O (AO), deoxyribonuclease B (AB), hyaluronidase (AH), and to the patients' own group of steptococci as well as to group A streptococci by indirect immunofluorescence (IF). Control sera were employed as well. Elevated titres of antibody to the enzymes occurred in 3 (OA), 5 (AB), and none (AH) of the patients' sera. The titre of the patients' antibody (by IF) to their own isolates was significantly higher (p less than 0.001) than that to streptococci of group A and that of normal controls to streptococci of similar groups. These data support a causative role for non-group A hemolytic streptococci in human pharyngitis.