ACTINOBACILLUS LIONIERESI 391 



Pathogenicity. — No exotoxin is formed. The organism is responsible for Actinobacillosis 

 in cattle. The virulence of different strains seems to vary considerably, and while 

 cattle inoculation experiments are successful with some strains, they are com- 

 pletely negative with others (Magnusson 1928). Most workers, including ourselves, 

 have been unable to produce any specific lesions in laboratory animals. The 

 following statements, therefore, which are taken from Lignieres and Spitz (1902), 

 must be accepted with considerable reserve. Subcutaneous inoculation of pure 

 cultures into cattle produces an abscess identical with those occurring spontaneously ; 

 in the pus granules are found consisting of bacilli surrounded by clubs. Intra- 

 peritoneal inoculation of a whole agar culture is fatal to a guinea-pig in 12 to 24 

 hours. Post mortem there is an abundant turbid peritoneal exudate, rich in 

 polymorphonuclear cells ; the organisms can be cultivated from the exudate, but 

 rarely from the blood. Intraperitoneal injection of ^-^ an agar culture into male 

 guinea-pigs produces a typical Straus reaction. In 2 days the testicles are mark- 

 edly inflamed, and the two layers of the tunica vaginaUs are adherent ; the scrotum 

 is red, swollen, and tender. The animal loses weight, and dies in 5 to 7 days. 

 Post mortem small purulent granules, the size of a hemp seed, formed of a very 

 thin membrane containing white or yellowish, thick, homogeneous pus, and scat- 

 tered over the peritoneal serosa^particularly on the inferior surface of the dia- 

 plrragm, the liver, spleen, and omentum. Around the testis there is a thick purulent 

 exudate, gumming the two layers of the tunica vaginalis together. In the pus 

 of these lesions tufts of clubs are found, though not in large numliers ; they are 

 rather smaller than those seen in cattle. Subcutaneous inoculation of guinea-pigs 

 causes a local abscess, which may resolve ; ulceration rarely occurs ; clubs are 

 not usually demonstrable in the pus. 



Rabbits, cats, and dogs are considerably more resistant than guinea-pigs, but 

 succumb to intravenous inoculation. SmaU lesions may develop in mice or rats 

 after subcutaneous inoculation. Pigeons and fowls are resistant. 



Actinobacillus actinomycetem-comitans. — Described by Klinger in 1912 under the 

 name Bact. actinomyceiem comitans. Found in lesions caused by Actinomyces bovis, as 

 densely packed Gram-negative cocco-bacilli (Colebrook 1920). In culture the rod forms 

 are 1-0-1 -5 /t long ; the coccoid forms are 0-6-0-8 n in diameter. Intermediate forms are 

 frequent. The organism is non-motile. In broth or liquid gelatin at 37° C. it forins iso- 

 lated, translucent granules, 0-5-1 -0 mm. in diameter, along the sides of the tube, most 

 numerous near the surface ; several hundreds of these colonies may develop. After some 

 days they fuse into a greyish-white mass, forming a ring round the tube and a pellicle 

 over the surface. The granules can be picked off the wall of the test-tube with a loop, 

 but are very difficult to break up. Later they may become opaque and greyish-white. 

 On agar it gives rise to small tough colonies, not unlike those of streptococci, adherent 

 to the medium. The organism flourishes under both aerobic and anaerobic conditions. 

 There is no growth at room temperature. Cultures live for 4 weeks. It is toxic on injec- 

 tion into rabbits, but does not set up a true infection. 



Actinobacillus actinoides. — This organism was isolated by Smith in 1918 from the 

 lungs of calves suffering from epizootic pneumonia, and called by him B. actinoides. 

 In the animal body it appears as a minute Gram-negative bacillus arranged in groups. 

 In the condensation water of coagulated serum it forms minute whitish flocculi, which 

 consist of a central mass of radiating non-branching filaments ending peripherally in 

 clubs. In tissue-agar cultures the organism grows as aggregations of rounded, ring-like 

 bodies, 2 ix in diameter, having a minute refringent speck on the periphery or near the 

 centre. There are thus three distinct forms in which this bacillus occurs. Most strains 

 are capsulated (Smith 19216), but the capsule does not stain with the usual dyes. Growth 

 occurs only under a raised pressure of COg — as in sealed tubes. On coagulated serum 

 whitish flocculi appear in the condensation water in 3 days at 37° C, and after several 



