Multiple fimbrial haemagglutinins in Serratia species

Fifty-six strains from nine Serratia species, grown under a variety of cultural conditions, were examined in rocked-tile tests for the presence of haemagglutinins (HAs) and with the electron microscope for fimbriae. All strains were haemagglutinating; most (71%) formed two or three of the different kinds of HA detected. These were: (i) a mannose-sensitive HA (MS-HA); (ii) a mannose-resistant, klebsiella-like HA (MR/K-HA); (iii) two mannose-resistant, proteus-like HAs (MR/P-HA), one of which showed broad-spectrum HA activity against different species of erythrocytes and the other narrow-spectrum HA activity. Five types of fimbriae associated with the different HAs were observed. This description of the fimbrial HAs in nine species of Serratia is the most comprehensive so far produced and should provide a basis for future studies directed towards elucidating the ecological role of the adhesins in in-vivo colonization by serratiae as commensals or pathogens.