Strains of Erysipelothrix rhusiopathiae isolated at 19 pig farms serving a certain abattoir, and on pork and in workers of this abattoir were studied. Mouse-pathogenic E. rhusiopathiae was found in pig slurry from two farms (11%). The strains belonged to serotypes 7 and 16 (both from the same farm) or were untypable. In pig slurry from the abattoir lairage only serotype 2 strains were found and all were pathogenic to mice. Mouse-pathogenic E. rhusiopathiae strains of serotype 2 were also recovered from 25 pork lions (25%). A mouse-pathogenic E. rhusiopathiae (serotype 2) strain was isolated from one of the 16 hand infections of slaughterhouse workers. The E. rhusiopathiae strains were phenotypically grouped by the API 50 CH system. Variations were demonstrated for the different serotypes. In 20 of 138 workers antibodies against E. rhusiopathiae were found; 14 had increased levels of IgG antibodies, seven had increased levels of IgM antibodies and one had an increased level of both.

Eight different serotypes of Erysipelothrix rhusiopathiae were isolated from 39 outbreaks of erysipelas in poultry, serotypes 1, 5, 6 and 9 being most prevalent. More than one serotype was demonstrated in five outbreaks. Only White Leghorns were affected as far as erysipelas in chickens is concerned, and 94% of the flocks were kept on sloping wire floors of the Pennsylvania system. No relationship between serotype, host predilection and virulence was observed, nor was there a seasonal distribution. The epidemiological and preventive aspects of the present findings are discussed.

SUMMARYExamination was made of 81 strains of Erysipelothrix rhusiopathiae isolated from chickens which had died of septicaemic erysipelas. The strains originated from two flocks producing eggs for consumption, 34 from Flock A and 47 from Flock B. Typing was performed by the tube precipitation and the agar gel precipitation test. All strains from Flock B belonged to type 1b, while 27 strains from Flock A belonged to type 4. The seven strains which could not be classified require further examination including production of antiserum for each strain in order to obtain, if possible, sera with precipitating antibodies.

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