390 ACTINOBACILLUS 



In lesions in the animal body small granules are found, which consist of tufts 

 of radially disposed clubs similar to those in actinomycosis. An important point 

 of difference is that the centre of the granule is occupied not by a Gram-positive 

 filamentous mycelium, such as is formed by Actinomyces bovis, but by minute 

 Gram-negative bacilli, which may quite readily be overlooked. Though both the 

 bacilli and the clubs formed by Actinohacillus lignieresi are Gram-negative, it is 

 possible to differentiate between them by a modified Ziehl-Neelsen stain, as was 

 pointed out by Bosworth (1923). If a section of affected tissue is stained with 

 carbol fuchsin, decolorized for 20 to 30 seconds with 1 per cent. H2SO4, and 

 counterstained with methylene blue, the clubs appear red and the bacilli blue. 

 For pus, one of the best stains is glycerine picro-carmine, which stains the clubs 

 yellow and the pus cells pink. 

 Cultivation. — Cultures are best obtained by grinding up infective pus in a mortar, and 

 seeding on to agar. Growth occurs readily under aerobic conditions, and less 

 readily under anaerobic conditions. The optimum temperature for growth is 

 37° C. ; very slight growth occurs at 20° C. 



On agar in 24 hours at 37° C. small, circular, bluish-grey, translucent colonies 



with a smooth surface and an entire edge, 



up to 1-5 mm. in diameter, are formed; 



further incubation results in a considerable 



• • increase in size — up to 4 mm. — due to peri- 



-" ^ .^» pheral extension of the colony. On an agar 



■" • , , ■ ' ^ slope the growth of freshly isolated strains is 



' poor, consisting of small, discrete, translucent 



V, . •'' bluish colonies, or of a thin, dry, confluent 



- . ' * layer of growth adherent to the medium. 



. . " ' ' After cultivation for some time in the labor- 



* , _ ' atory, the organism grows more readily, giving 



♦ ' •' • a confluent, filiform, viscous growth with a 

 ' ' thickened edge. 



In stab agar there is a whitish opaque spot 



at the surface ; no growth occurs down the 



stab. In gelatin stab growth is very poor 



Fig. 65.-Actinobacillus lignieresi. From ^'^^ is not visible for some days. A smaU 



a liver agar slope, 2 days, 37° C. aero- opaque spot appears at the surface ; no 



bically ( X 1000). growth occurs down the stab, and there is no 



Uquefaction. 

 Coagulated serum is not a very favourable medium ; only a thin whitisli 

 growth js formed. 



On acid potato there is no growth. On alkaline potato a sUght, gUstening, 

 greyish -yellow growth appears. 



In peptone broth there is a sUght uniform turbidity. In old cultures, a surface 

 film may develop, and an abundant deposit. Growth in broth is improved by serum . 

 Resistance. — The organism is kiUed by heating to 62° C. in 10 minutes. It rapidly suc- 

 cumbs to drying. Cultures do not live long, and should be transplanted every 

 few days. Infected pus preserved in sealed tubes may remain virulent for a month 

 or two. 

 Biochemical Reactions. — The fermentative ability of this organism is a little doubtful. 

 Glucose, maltose, mannitol, and sucrose are generally rendered acid, though not 

 markedly so, in a day, while lactose may be fermented later. Acid is produced 

 in litmus milk, but no clot. Indole is formed, apparently in small quantity. 

 Antigenic Structure. — Little kiiown. Tunnicliff (1941) states that bovine and ovine strains 

 appear to be similar, l)ut that strains of either type may fail to agglutinate with 

 a type serum. 



