Detection of K88 and K99 fimbrial antigens on Escherichia coli by coagglutination.

Coagglutination was used to detect K88 and K99 fimbrial antigens on Escherichia coli, and results were compared to an enzyme immuno assay (EIA). When pili suspensions were tested by both methods, 28 of 66 cultures were shown to have K88 and 11 of 31 cultures had K99 antigens. No pili suspensions were positive by coagglutination that were not positive by EIA. Testing of cell suspensions gave equivalent results to pili suspensions for K99 when tested by coagglutination. Two cell suspensions reacted with the K88 coagglutination which could not be confirmed by testing of pili suspensions, while a further 20 out of 43 cultures gave equivalent results with both cell and pili suspensions for K88 when tested by coagglutination.