INTERACTIONS WITH LECTINS AND AGGLUTINATION PROFILES OF CLINICAL, FOOD, AND ENVIRONMENTAL ISOLATES OF LISTERIA

On the basis of preliminary trials with 14 collection strains of Liste ria, five lectins (Canavalia ensiformis, concanavalin A; Griffonia sim plicifolia lectin I; Helix pomatia agglutinin; Ricinus communis agglut inin; and Triticum vulgaris wheat germ agglutinin) were selected to se t up a microtiter agglutination assay. The lectin agglutination profil es of 174 clinical, food, and environmental strains of Listeria monocy togenes, Listeria innocua, and Listeria seeligeri were investigated. D ata on the standard determination of the antigenic structure were avai lable for clinical strains; nonclinical isolates were assigned to sero group 1 or 4 with commercial antisera. The listeria-lectin interaction was related to serological type rather than species; in particular, t he strains assigned to serogroup 1 or belonging to serovars 1/2a, 1/2b , 1/2c, 3a, 3b, and 7 were never agglutinated by G. simplicifolia lect in I. The five-lectin set proved to be a capable of detecting differen ces between serologically identical isolates of L. monocytogenes. Of t he 150 isolates of this species, 144 were distributed over 15 differen t lectin agglutination profiles and 6 autoagglutinated, the overall ty peability being 96%. However, the profiles encountered among L. monocy togenes isolates were not randomly distributed. With strains assigned to serogroup 1 or belonging to serovars 1/2a, 1/2b, 1/2c, and 3b, the clinical isolates fell into only two of the eight patterns recorded ov erall; with strains of serogroup 4 and serovar 4b, food and environmen tal isolates were distributed over eight of the nine patterns found in total, while clinical isolates were distributed over five patterns. I n a comparative study of 15 epidemiologically relevant isolates of L. monocytogenes from five distinct outbreaks, strains with identical pha ge types and/or DNA fingerprints displayed identical lectin profiles. The heterogeneity of agglutination profiles may form the basis of a ne w approach to L. monocytogenes typing.