Validity of rapid antigen detection testing in group A beta-hemolytic streptococcal tonsillopharyngitis.

OBJECTIVE

To evaluate the utility of rapid antigen detection testing (RADT) for the diagnosis of group A beta-hemolytic streptococcal tonsillopharyngitis in children, and to detect the sensitivity and specificity of rapid antigen detection of group A beta-hemolytic streptococci from throat specimen compared with throat culture.

METHODS

Rapid antigen detection and throat culture results for group A beta-hemolytic streptococci from outpatients attending university hospital between 1st January 2011 and 31st of December 2011 were evaluated retrospectively. The antigen test negative-throat culture positive patients were investigated for streptococcal carriage. For this purpose, the throat culture results taken from these patients were reviewed after treatment.

RESULTS

Eight hundred and ninetytwo children were included in the studywith a mean age of 5.34 y. There were 639 and 253 children in two groups with age of 0-6 and 7-17 y, RADT sensitivity and specificity were found to be 59.5 % and 97.2 %, respectively. The positive predictive value was 87.1 %, whereas negative predictive value was 88.4 %. After treatment of 74 patients with throat culture positive and antigen test negative. Group A beta-hemolytic streptococci were isolated in 12 of them (16.2 %) and accepted as a carrier.

CONCLUSIONS

The low sensitivity of the RADT may be related to streptococcal carriage in some patients. The throat culture should be repeated after treatment to detect streptococcal carriage.