Phenotypic characteristics of Riemerella anatipestifer and similar micro‐organisms from various hosts

Abstract

A total of 199 Riemerella anatipestifer (RA) and RA‐like field strains isolated culturally from birds of 12 different species and from pigs were characterized using classical phenotypic and chemotaxonomic tests. The RA reference strain ATCC 11845 was included in the study. On the basis of the classical phenotypic characteristics studied and the numerical analysis of the whole‐cell fatty acid patterns, the RA reference strain and 123 field isolates were assigned to the indole negative (IN) variant and 10 isolates to the indole positive (IP) variant of the species RA. The IN strains were isolated not only from poultry and free‐living wild ducks, but also from pigs, guillemots and from a budgerigar and a herring gull. All the IP isolates were isolated from domestic ducks. One field strain from a chicken and one from a black‐headed gull, which were distinguished from RA mainly by the negative a‐glucosidase reaction and production of yellow pigment respectively, showed fatty acid methyl ester profiles chemotaxometrically different from those of RA. Another 64 field strains isolated from domesticated ducks, geese and muscovy ducks with signs and lesions very similar to those caused by RA were phenotypically and chemotaxometrically clearly different from RA and could not be classified to any of the known species. This possible bacterial pathogen is therefore given the preliminary designation of Riemerella‐like (RA‐L) taxon 1502.