EPIDEMIOLOGIC EVIDENCE FOR LANCEFIELD GROUP-C BETA-HEMOLYTIC STREPTOCOCCI AS A CAUSE OF EXUDATIVE PHARYNGITIS IN COLLEGE-STUDENTS

The isolation rates of strains of group C beta-hemolytic streptococci from throat swab cultures of patients with exudative pharyngitis, the common cold, and healthy controls were compared, By using a cohort stu dy design in a college health service, patients with exudative pharyng itis were retrospectively identified by description of tonsillar exuda te on chart review. Patients with rhinoviral infection were prospectiv ely identified during a common cold study. Healthy controls were prosp ectively recruited from patients presenting with noninfectious conditi ons. Isolation of Lancefield group A and C beta-hemolytic streptococci from throat cultures was used as an outcome measurement. A total of 2 65 students (62% female; average age, 20.2 years) with exudative phary ngitis were identified, A total of 75 students (60% female; average ag e, 21.7 years) from a common cold study with rhinoviral infection were identified. A total of 162 students (53% female; average age, 22.6 ye ars) were recruited as healthy controls. Group A beta-hemolytic strept ococci were isolated from 5% of patients with pharyngitis but none of those with rhinovirus (P = 0.045) and none of the controls (P = 0.007) . Group C Streptococcus dysglactiae subsp. equisimilis was isolated fr om 11% of patients with pharyngitis but none of those with rhinovirus (P = 0.006) and 2% of controls (P = 0.001). Lancefield group C Strepto coccus anginosus was isolated from 8% of patients,vith pharyngitis but 3% of those with rhinovirus (P = 0.18) and 1% of controls (P = 0.006) . Heavier growth of colonies on the primary culture plate was observed for patients from whom S. equisimilis and group A beta-hemolytic stre ptococci were isolated. Lancefield group C beta-hemolytic streptococci appear to be associated with exudative pharyngitis in college student s.