[Comparative analysis of clinical and laboratory methods for diagnosing streptococcal sore throat]

Diagnosis and correct treatment of group A streptococcal sore throat is important particularly to prevent non-suppurative sequelae. Clinical findings continue to be used to differentiate streptococcal infection from viral sore throat. The American Academy of Pediatrics recommends that streptococcal sore throat diagnosis should always be performed by microbiological identification methods. The aim of this study is to evaluate the accuracy of clinical diagnosis in comparison with culture and rapid test.

Children aged 2 to 13 years who had received a clinical diagnosis of sore throat and sought treatment at the pediatric emergency unit of São Paulo Santa Casa were evaluated and those with clinical signs or viral infection were excluded. Clinical findings were recorded and swabs were taken for group A Streptococcus cultures and a Streptococcus rapid test.

The culture was positive in 96 (24.4%) of the 376 children evaluated. The presence of petechiae, purulent exudate and painful tonsils were more likely to occur in children with positive streptococcus cultures, however they exhibited low diagnostic accuracy. The doctors' subjective evaluation failed to identify 21% of positive cases and antibiotics were prescribed in 47% of negative cases, compared with 3 and 6%, respectively, for the rapid test.

A microbiologic method is necessary for the correct prescription of antibiotics in children with streptococcal sore throat.