Mannose-resistant hemagglutination, enzyme-linked immunosorbent assay, and immune electron microscopy for detection of K99 fimbrial antigen in Escherichia coli from calves.

Mannose-resistant hemagglutination (MRHA) was evaluated for identification of Escherichia coli with K99 fimbriae. The sensitivity and specificity of MRHA, relative to the enzyme-linked immunosorbent assay, were 21 and 79%, respectively. Disagreement between the tests may have been due in part to separation of pili from the cells, with resultant enzyme-linked immunosorbent assay-positive, MRHA-negative tests. MRHA was not useful as the sole means for the identification of E. coli with K99 fimbriae.