Pharyngitis in Children is Often Due to Streptococcal Infection

Pharyngeal swab are taken for rapid antigen testing and/or culture to diagnose the presence of group A Streptococcus (GAS) pharyngitis.

Standard throat swabs can be tested for the presence of GAS by using antigen detection methods such as Abbott Signify Rapid Strep A test (Abbott Laboratories, Abbott Park, IL, USA) or by culturing for the bacteria in specific media.

In a recent meta-analysis carried out at the University of Pittsburgh (Pittsburgh, PA, USA) scientists determined the prevalence of streptococcal infection among children who presented with sore throat and prevalence of streptococcal carriage among asymptomatic children. A substantial proportion of children with pharyngitis probably have group A streptococcal infection, and furthermore, about one in every eight healthy children is a carrier.

The study included only children under the age of 18 and reported that the prevalence of GAS in children presenting with sore throat is 37% overall and 24% in children younger than five, but 12% of asymptomatic children over five carry GAS. The prevalence rates of GAS disease and carriage varied by age as children who were younger than five years had lower rates of throat cultures that were positive for GAS. The relatively high probability of GAS disease and acute rheumatic fever in school-aged children, as compared with adults and children who are younger than five years, suggests that testing of school-aged children who present with sore throat is beneficial.

Nader Shaikh, M.D., M.P.H., said, "Post treatment cultures are unnecessary in the majority of patients with GAS pharyngitis. However, in selected children with recurrent pharyngitis, post treatment testing may help to differentiate children with true recurrent GAS pharyngitis from carriers. Children who are carriers are likely to have persistent GAS even after being treated with appropriate antimicrobial agents." It is probably not wise to test children who have absolutely no signs or symptoms of pharyngitis as this will lead to unnecessary antibiotic use. The study was published in August 2010 in Pediatrics.

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Abbott Laboratories
University of Pittsburgh