Diagnosis of streptococcal pharyngotonsillitis in children and adolescents: clinical picture limitations

OBJECTIVE: To assess the utility of clinical features for diagnosis of streptococcal pharyngotonsillitis in pediatrics. METHODS: A total of 335 children aged 1-18 years old and presenting clinical manifestations of acute pharyngotonsillitis (APT) were subjected to clinical interviews, physical examinations, and throat swab specimen collection to perform cultures and latex particle agglutination tests (LPATs) for group A streptococcus (GAS) detection. Signs and symptoms of patients were compared to their throat cultures and LPATs results. A clinical score was designed based on the multivariate logistic regression analysis and also was compared to throat cultures and LPATs results. Positive throat cultures and/or LPATs results were used as a reference standard to establish definitive streptococcal APT diagnosis. RESULTS: 78 children (23.4%) showed positivity for GAS in at least one of the two diagnostic tests. Coryza absence (odds ratio [OR]=1.80; p=0.040), conjunctivitis absence (OR=2.47; p=0.029), pharyngeal erythema (OR=3.99; p=0.006), pharyngeal exudate (OR=2.02; p=0.011), and tonsillar swelling (OR=2.60; p=0.007) were significantly associated with streptococcal pharyngotonsilitis. The highest clinical score, characterized by coryza absense, pharyngeal exudate, and pharyngeal erythema had a 45.6% sensitivity, a 74.5% especificity, and a likelihood ratio of 1.79 for streptococcal pharyngotonsilitis. CONCLUSIONS: Clinical presentation should not be used to confirm streptococcal pharyngotonsilitis, because its performance as a diagnostic test is low. Thus, it is necessary to enhance laboratory test availability, especially of LPATs that allow an acurate and fast diagnosis of streptococcal pharyngotonsilitis.