[Incidence of streptococcal pharyngitis]

To determine the incidence of streptococcal pharyngitis in patients younger than 2 years of age, and to evaluate the role of group C streptococci as a pathogenic agent in acute pharyngitis through throat culture in symptomatic patients.

We performed a retrospective descriptive study of patients with clinical symptoms of acute pharyngitis and fast detection of streptococcal antigen and/or exudate culture who attended the emergency department between February 2004 and February 2005.

Group A beta-hemolytic streptococcus (GAS) was isolated by pharyngeal culture in 85 patients aged less than 2 years (12.6%). In these patients the fast test displayed lower sensitivity and positive predictive value (PPV) (sensitivity: 78%; PPV: 69%, p < 0.01). Patients aged less than 2 years had a greater frequency fever, exanthema and catarrhal symptoms than older children (p < 0.01). In the younger age group, erythromycin resistance rates increased to 24.7% (p = 0.08). Group C streptococcus was isolated in 5.2% (43 patients). The most frequent reason for consultation was fever (74.4%) and the most common findings on examination were abnormal pharynx in 90.7%, odynophagia and adenopathies in 55.8%. Two incidence peaks (in May and September) were observed, with sporadic cases throughout the year.

In our sample, the percentage of GAS in patients aged less than 2 years was higher than that reported in other series. In this age group, the sensitivity of the fast test is lower than in other age groups and there is a higher rate of erythromycin resistance. The percentage of tonsillitis due to serotype C was also slightly higher than expected. Two peaks of incidence were observed, similar to those occurring with SGA, with sporadic cases throughout the year.