Microbiological and epidemiological study of streptococcal sore throat at a children's clinic: a one-year study.

From October 1973 to September 1974, throat cultures were taken from 578 patients who referred to the Children's Clinic with upper respiratory tract infection. One hundred fifty-one (26%) of the sick children yielded beta-hemolytic streptococci and 427 (74%) of the pharyngitis cases were considered as viral. The most susceptible ages for streptococcal and viral pharyngitis were 5-8 and 2-6 years respectively. The peak seasonal incidence for streptococcal sore throat was from late autumn to early spring. There was a positive correlation between the incidence of upper respiratory infection and streptococcal isolation. From 100 strains of beta-hemolytic streptococci isolated and tested, 86 were group "A", 4 group "C", 2 group "G" and 8 non-groupable. From 86 group "A" strains. 71 (82%) were typable by agglutination ("T"-typing), but only 49 (57%) by precipitation ("M"-typing). The most prevalent "M" types were types 1 and 12. There was 95% correlation between serological and bacitracin disk method for grouping of hemolytic streptococci. All strains isolated were sensitive to penicillin, erythromycin and chloramphenicol, but 11 strains were resistant to tetracyclin.