Comparison of Fluorescent Antibody, Precipitin, and Bacitracin Disk Methods in the Identification of Group A Streptococci

Comparison of fluorescent antibody, bacitracin susceptibility, latex agglutination, coagglutination, and API 20S for identifying group A streptococci

“…In our study, results show that all three sources of bacitracin yielded high reliability when identifying group A streptococci as compared with the Lancefield precipitin test. The falsenegative rate of 3-4% is consistent with previous reports by Estela and Shuey (1963) and Facklam et al (1974). The falsepositive rate for BBL, Raven, and Difco bacitracin disks was 19, 13, and 14%, respectively.…”

“…Fluorescent antibody (FA), which is used by many laboratories as a standard method to identify group A streptococci, is easy to perform, faster than bacitracin susceptibility testing, and accurate provided good antiserum is available (Arvilommi et al 1978). Besides the availability of good antiserum, the one disadvantage of FA is the cross-reactivity with other streptococci if the antiserum is not of good quality (Chitwood et al 1969;Estela and Shuey 1963;Watson et al 1975;Arvilommi et al 1978). Recently, the use of coagglutination and latex agglutination techniques have been used in clinical laboratories for the rapid identification of group A streptococci and other clinical isolates.…”

“…Recently, the use of coagglutination and latex agglutination techniques have been used in clinical laboratories for the rapid identification of group A streptococci and other clinical isolates. These methods have been compared with FA, bacitracin susceptibility, and precipitation reactions (Arvilommi et al 1978;Estela and Shuey 1963;Facklam et al 1979;Lue et al 1978;Petran 1964;Rosner 1977). These reports have shown the accuracy of latex and coagglutination to be equal to or better than FA or bacitracin, when compared with the Lancefield test.…”

“…The results obtained were compared with that of the Lancefield precipitin test. Although these methods have been evaluated and compared previously (Arvilomrni et al 1978;Estela and Shuey 1963;Facklam et al 1979;Lue et al 1978;Petran 1964;Rosner 1977;Slifkin and PouchetMelvin 1980;Stoner 1978;Watson et al 1975), we are not aware of a study comparing all simultaneously.…”

Rapid Extraction Method with Pronase B for Grouping Beta-Hemolytic Streptococci

“…Since Maxted (8) and Levinson and Frank (6) reported the use of bacitracin sensitivity to differentiate group A streptococci from other beta-hemolytic streptococci, the presumptive bacitracin disc method has been used extensively in diagnostic laboratories. Several reports (1,2,12) indicate that the error of this method may be greater than originally conceived and that specific grouping of beta-hemolytic streptococci would be more desirable from a clinical viewpoint.…”