Characterization of 2 groups of Actinomyces-like bacteria isolated from purulent lesions in pigs.

Two groups of Actinomyces-like bacteria isolated from purulent lesions in pigs, were characterized and compared with Actinomyces pyogenes of porcine origin. One group showed characteristics which differed in many respects from A. pyogenes but which corresponded more closely to those of the non-official species 'Actinomyces suis'. Certain carbohydrate reactions differed from those given in earlier descriptions. This group was isolated only from purulent vaginal discharge and aborted foeti. The other group resembled the 'A. suis'-like bacteria but differed in its colony morphology, hippurate and to some extent also in its cellobiose and gluconate reactions and in its habitat. It was concluded that 'A. suis' may occur in lesions other than mammary actinomycosis in areas where this disease is extremely rare, and that its natural habitat is the genital tract of pigs. Furthermore a probably related group exists, which is found in purulent lesions located mainly outside the porcine genital tract. These organisms appear to be as frequent in these types of lesions as A. pyogenes, with whom they can easily be confused in routine diagnostic bacteriology.