In total, 86 enterococcal strains including representatives of most of
the described species were tested for the ability to agglutinate huma
n, sheep, and rabbit erythrocytes. Five strains did not react with any
of the erythrocytes tested, and 81 (94.2%) strains agglutinated only
rabbit erythrocytes. The hemagglutination titers ranged from 2 to 64.
Loss of the hemagglutination activity was observed when rabbit erythro
cytes were treated with trypsin or neuraminidase. Trypsin treatment of
the bacterial suspensions also caused loss of the agglutination abili
ty. On the other hand, heat treatment of bacterial suspensions increas
ed the efficiency of the interactions, and higher titers were obtained
, Assays for inhibition of hemagglutination were performed with alpha-
D-fucose, alpha-D-galactose, beta-D-galactose, D-glucose, N-acetyl-gal
actosamine, N-acetyl-glucosamine, N-acetylneuraminic acid, N-acetylneu
raminic acid-lactose, and fetuin. Only fetuin was able to inhibit the
hemagglutination reactions, The results showed that hemagglutination p
roperties are common to the different enterococcal species tested. The
y also suggest that enterococci possess hemagglutinins of proteic and
non-proteic nature that are involved in the attachment to sialic acid-
containing receptors on the surface of rabbit erythrocytes.