Rapid slide agglutination test for Lancefield grouping of streptococci.

A rapid slide agglutination test (the Phadebact [PB] Streptococcus test) was compared with the standard autoclave extraction method of Lancefield and presumptive clinical laboratory tests for grouping of streptococci (bacitracin disk sensitivity for group A and sodium hippurate hydrolysis for group B). Identification of group A streptococci by the PB kit was statistically as accurate as by the Lancefield method, whereas bacitracin grouping was significantly less accurate than the Lancefield method (P = less than .02). With regard to group B, there was no statistically significant difference between the PB test and the sodium hippurate test. The PB test correctly identified all group C and G streptococci. The PB kit provides a rapid and reliable method for Lancefield grouping of streptococci.