Evaluation of a rapid test for direct detection of group A streptococcal antigen in throat swabs. Study of 4 commercial test systems

: Four commercially prepared test reagent kits for the rapid screening of throat swabs for group A streptococci were examined in comparison to bacteriological cultures of 963 double throat swabs. The sensitivities of the test systems were 86.7% (Abbott Test Pack Strep A), 81.8% (Hybritech Tandem Icon Strep A), 79.6% (Pharmacia Phadirect Strep A), and 72.6% (Wellcome Reveal Colour Strep A) respectively. The specificity of the four tests was above 90%. Marked variations between different test reagent batches could be observed. The two tests based on the enzyme immunoassay principle proved to be superior to the agglutination tests investigated with respect to sensitivity and reading accuracy. Our results are evaluated in the light of the published literature on these tests.