Perplexity and precision in the diagnosis of streptococcal pharyngitis.

Abstract

Group A streptococci are found in a modest 35% of children with pharyngitis; about one half of those with a positive culture develop an antibody rise. Only patients with an antibody response appear to be at risk of developing nonsuppurative complications. Unhappily, attempts to identify such patients in advance by clinical or bacteriological criteria or both result in a vast margin of error. Adenitis plus a positive culture has the best (61%) predictive value for an antibody response, but adenitis is present in only 42% of patients with group A streptococci who develop an antibody rise. Children with pharyngitis and a positive throat culture who fail to develop an antibody rise often show relatively high acute-phase antibody titers, suggesting previous rather than present streptococcal infection. Current polarization of attitudes will persist until more reliable methods are found for diagnosing streptococcal infection.