Objective: To determine the prevalence and clinical features of beta-haemolytic streptococcal infection in children with acute pharyngitis and thereby to define those requiring antibiotic therapy.
Design: Prospective 2:1 case--control study.
Setting: Emergency Medicine Department of the Royal Children's Hospital, Melbourne, between May 1994 and May 1995.
Participants: Cases (n = 271) were the first 10 self-referred children in each week with pharyngitis and no antibiotic use in the previous week. Controls (n = 135) were age-matched children without infection.
Main outcome measures: Presence of groups A, C or G beta-haemolytic streptococci in oropharyngeal cultures; demographic and clinical characteristics.
Results: Group A beta-haemolytic streptococci (GABHS) were isolated from significantly more case than control children (cases, 57/271 [21%]; controls, 9/135 [7%]; odds ratio [OR], 3.7; P < 0.001). Groups C and G beta-haemolytic streptococci were isolated from 10 (4%) and 5 (2%) case children, respectively, but not from controls. Age > or = 4 years, tender cervical lymph nodes, pharyngotonsillitis, absent coryza and scarlatiniform rash were significantly associated with GABHS (P < 0.02). GABHS was uncommon in children aged < 4 years (4%), but was present in 12 of 14 children > or = 4 years with a rash (86%). However, most cases lacked a rash, and for children > or = 4 years likelihood of GABHS varied from 10%-65%, depending on other clinical features.
Conclusions: In children aged < 4 years, GABHS is an unlikely cause of acute pharyngitis and symptomatic treatment alone should be considered. In children > or = 4 years, the likelihood of GABHS being the cause of acute pharyngitis increases with presence of scarlatiniform rash, pharyngotonsillitis and tender cervical nodes.