386 ACTINOMYCES 



form or club-shaped swellings occurring terminally, sub-terminally, or in some 

 other situation^ — hence the term " moniliformis.'''' These swellings may be 2-5 

 times the diameter of the filament, and may project from one side only. Accord- 

 ing to Klieneberger (1942) the moniliform appearance and certain other appearances 

 are due to the pleuropneumonia or LI organism, which is a constant companion 

 to Actinomyces muris. In the animal body the morphology is more regular and 

 bacillary. Great irregularity in depth of staining. Non-motile. Usually 

 described as Gram-negative, but may be Gram-positive in young cultures. 

 Non-acid-fast. (See Fig. 64.) 



Nutrient Agar at 37° C. — No growth. 



Glucose Agar at 37° C. — No growth. 



Serum Agar Plate. — 2 clays at 37° C. Circular, greyish-yellow, low convex, almost water- 

 clear, amorphous colonies, 0-2-0-3 mm. in diameter, with smooth glistening surface 

 and entire edge ; butyrous in consistency and easily emulsifiable. No differentiation. 

 Little or no increase in size on further incubation. 



Gelatin Stab. — 7 days at 20° C. No growth. 



Nutrient Broth at 37° C. No growth. 



Serum, Broth. — 2 days at 37° C. No turbidity. Abundant, greyish-white, coarsely granular 

 sediment, looking Uke fluffy bread crumbs, miniature cotton balls, or tiny snow 

 flakes, not disintegratmg completely on shaking. No surface growth. No odour. 



Glucose Agar Shake. — 7 days at 37° C. No growth. 



Loeffer^s Serum. — 2 days at 37° C. Discrete, circular, low convex colonies, similar to 

 those on serum agar, but rather larger — 0-5-0-7 mm. in diameter. 7 days ; some 

 colonies may show a differentiation into a slightly raised umbonate centre with 

 a flatter periphery having an irregular or crenated edge ; surface appears finely 

 granular and rather duU. Growth may be confluent from the start, and appear 

 shghtly raised, colourless, with a glistening beaten-copper surface and a more or 

 less entire edge. No liquefaction, even after 3 weeks. 



Dorset Egg. — 2 days at 37° C. Similar to colonies on Loeffler's serum, but perhaps slightly 

 smaller — 0-3-0-6 mm. in diameter. No liquefaction, even after 3 weeks. 



Horse Blood Agar. — 2 days 37° C. Colonies resemble those on serum agar. No haemolysis. 



Potato. — 7 days at 37° C. No growth. 



MacConkeys Agar. — 7 days at 37° C. No growth. 



Growth in Developing Egg. — Inoculated on to the chorio-allantoic membrane of the develop- 

 ing chick embryo, Actino. muris invades the embryo and becomes localized almost 

 exclusively in the synovial lining of the joints, where it appears to grow mainly 

 as an intracellular parasite ; the embryo dies within 4 days (Buddingh 1944). 



Resistance. — Destroyed in serum broth by heating to 55° C. for 30 minutes. Dies out in 

 culture very readUy. Serum broth cultures may remain viable at 37° C. for a week. 



Metabolism. — Grows aerobicaUy, but grows equally well or better under anaerobic con- 

 ditions. Growth said to be improved by 10 per cent. COj. Optimum temperature 

 37° C. ; little or no growth at 22° C. No haemolysin for horse red cells. No pigment 

 formation. No growth on ordinary media, but growth occurs in presence of serum, 

 ascitic fluid, or blood ; not improved by glucose or glycerol. 



Biochemical. — Not thoroughly studied. In serum sugar media acid is produced within 

 3 days in glucose and sahcin, sometimes in maltose and lactose. Litmus milk 

 unchanged. Indole — ; M.R. — ; V.P. — ; Nitrate reduction — ; HjS — ; cata- 

 lase — ; M.B. reduction — . 



Antigenic Structure. — Different strains appear to be antigenicaUy homogeneous. 



Pathogenicity. — Responsible in man for one type of rat-bite fever — sometimes described 

 as infectious erythema or Haverhill fever. May give rise to an epizootic disease 

 in mice characterized by oedematous swelling of the feet and legs, arthritis, con- 

 junctivitis, and lymphadenitis. Intraperitoneal inoculation of mice with 0-5 ml. 

 of a serum broth culture is usually fatal in 1-2 days ; no characteristic post-mortem 



