Clinical predictors of streptococcal pharyngitis in adults

Background: Acute pharyngitis in children is one of the most frequent illnesses for which primary care physicians are consulted. It is caused more frequently by viruses than by bacteria, but it is difficult to differentiate the causative agent by clinical signs alone. Group A Streptococcus accounts for 30% of children with a sore throat, and only in these cases is antibiotic therapy definitely indicated. However the frequency and symptomatology of streptococcal pharyngitis in adults is not well established. Objectives: To examine the clinical features that could distinguish sore throat caused by beta-hemolytic group A Streptococcus in adults. Methods: Patients aged over 16 years old (n = 207) who presented with a sore throat to community clinics were examined and throat cultures were taken. The microbiologic confirmation of Group A Streptococcus was correlated with symptoms and clinical signs by univariate analysis. Results: About 24% of the patients with positive cultures were younger individuals. Chills, absence of cough, pain in swallowing, absence of rhinitis, headache, vomiting, tonsillar exudate, oral malodor, fever > 38degreesC and sweats had high sensitivity but low specificity for streptococcal pharyngitis. Univariate analysis suggested that chills and pharyngeal exudate had the greatest predictive value for streptococcal pharyngitis (P = 0.044, odds ratio 2.45; P = 0.001, OR 5.49, respectively). When compared with a published scoring method (Centor criteria), large inconsistencies were found. Conclusion: Our adult population had a relatively high prevalence of group A Streptococcus, and their presentation differed from that of pediatric patients. In primary care, a throat swab culture is not necessary in adults with a low score (0-1 points).