PATHOGENICITY 397 



biotin, and haemin are added (Porter and Pelczar 1941). Growth of both organisms 

 occurs between about 15° and 44° C, but is best at 30° to 37° C. 



Biochemical Characters.— The fermentative activity of Erysipelothrix is less 

 than that of ListereUa. Neither organism forms gas. Erysipelothrix produces 

 acid in glucose and lactose ; ListereUa produces acid in glucose, maltose, salicin, 

 mannose, rhamnose, and dextrin, and slowly or in only small amount in lactose, 

 sucrose and glycerol (see Deem and WilUams 1936, Barber 1939, Julianelle 1941, 

 Harvey and Faber 1941). According to Barber (1939) and Julianelle (1941) 

 ListereUa gives a positive and Erysipelothrix a negative Voges-Proskauer reaction, 

 though Harvey and Faber (1941) record a negative reaction for the strains of 

 ListereUa that they studied. 



Antigenic Structure. — There is general agreement that Erysipelothrix and 

 ListereUa are antigenically distinct. Watts (1940), who studied 43 strains of 

 Erysipelothrix, found that 38 appeared to belong to one antigenic type and 5 to 

 another. Each group possessed a heat-stable specific antigen, and in addition 

 two heat-labile antigens, which were present in different proportions in the two 

 groups and were responsible for cross-agglutination. Seastone (1935), Webb and 

 Barber (1937), Schultz, Terry, Brice, and Gebhardt (1938), Paterson (1939, 1940a), 

 and Julianelle and Pons (1939) have brought evidence to show the existence of 

 some antigenic diversity among ListereUa strains. Paterson recognizes four types, 

 the division being made primarily on the H and secondarily on the antigens. 



Pathogenicity. — Both organisms have a wide range of pathogenicity for animals 

 under natural conditions, and both may occasionally infect man (pp. 1285-7). 

 The diseases to which they give rise will be described in Chapter 58 ; here we 

 shall concern ourselves with their effect on laboratory animals. Three striking 

 characteristics are possessed, though in differing degree, by Erysipelothrix and 

 ListereUa. Both produce a considerable monocytosis in rabbits, pin-point focal 

 necroses in the liver of mice, and conjunctivitis in rabbits and mice. After intra- 

 venous inoculation into rabbits each of the organisms gives rise to a considerable 

 monocytosis, which reaches its maximum in 3 to 7 days (Webb and Barber 1937, 

 Barber 1939). In mice inoculated subcutaneously or intraperitoneally focal 

 necroses of the liver, up to pinhead in size, are nearly always found post mortem 

 in ListereUa infections, but are much less numerous and striking in infections 

 with Erysipelothrix. Conjunctivitis, on the other hand, is commoner in Erysipelo- 

 thrix than in ListereUa infections of mice (Barber 1939). If, however, the organisms 

 are instilled into the conjunctival sac of the rabbit, or rubbed gently on the everted 

 lid, ListereUa gives rise to a severe conjunctivitis and keratitis, whereas Erysipelo- 

 thrix causes a milder conjunctivitis without keratitis (Anton 1934, Graham, Hester, 

 and Levine 1940, Julianelle 1941). According to Barber (1939), ListereUa kills 

 guinea-pigs but not pigeons ; Erysipelothrix kills pigeons but not guinea-pigs. 

 In assessing these differences it must be remembered that the virulence of both 

 organisms is subject to variation, and that unless freshly isolated strains in the 

 smooth phase are used the results of inoculation may be equivocal. In general 

 it may be said that both organisms give rise to a septicaemic infection, and that 

 Erysipelothrix has a tendency to localize in the skin, endocardium, and joints, 

 and ListereUa in the liver, myocardium, and central nervous system. Both 

 Erysipelothrix and ListereUa appear to be more virulent in the smooth than in 

 the rough form (Schoening et al. 1938, Barber 1939). 



