460 CORYNEBAGTERIUM 



human throat, were originally studied by Barratt (1933), who found them to have the 

 power of liquefying gelatin, a property possessed by C. ovis but not by C. diphtherice. 

 Petrie and McClean found that one of these strains produced both diphtheria toxin and a 

 toxin that was immunologically related to that of C. ovis. The remaining strains produced 

 only a toxin related to that of C. ovis. Two strains, similar to those of Barratt, have 

 been described more recently by Wright at Liverpool (Report 1942). Both strains resembled 

 the gravis type of diphtheria bacillus in their colonial appearance, fermentation of starch, 

 and virulence to the guinea-pig, but differed from it in liquefying gelatin in slope culture 

 at 22° C, though not in stab culture at 22° C. or 37° C, in being inagglutinable with gravis 

 type antisera, and in being apparently unaffected by diphtheria antitoxin ; even 10,000 

 units of antitoxin failed to protect guinea-pigs against the usual test dose of culture, 

 and the organisms were easily recoverable from the heart blood. One strain killed a rat 

 injected intraperitoneally. Whether the toxin formed by these strains was neutralized 

 by C. ovis antitoxin is not recorded. 



C. pyogenes was first described by Lucet (1893), who isolated it from suppurative 

 lesions in cattle. Similar organisms were isolated from similar lesions in cattle 

 and swine by Grips (1898), Kiinnemann (1903) and Glage (1903). Since then they 

 have been recorded by many workers (see Holth 1908, Poels 1912, Ward 1917). 

 The lesions to which they most frequently give rise under natural conditions 

 appear to be suppurative pneumonia, suppurative arthritis, and other suppurative 

 lesions, including mastitis, the animals affected being cattle, pigs, sheep, and goats 

 (see Merchant 1935, Magnusson 1938). 



Among laboratory animals, the rabbit appears to be most susceptible, guinea- 

 pigs less so, and mice relatively resistant (see Holth 1908, Ward 1917, Brown and 

 Orcutt 1920). 



The injection of Uving cultures of G. pyogenes into the rabbit is followed by the develop- 

 ment of locahzed abscesses if the injections are given subcutaneously. If they are given 

 intravenously, or if generalization occurs after a subcutaneous inoculation, abscesses 

 develop in the bones and joints, less frequently in other organs. 



C. ovis and C. pyogenes produce suppurative lesions in animals ; both liquefy 

 gelatin, and both produce haemolysis. There is, however, a general consensus of 

 opinion among those who have worked with them that they are different species. 

 They tend to affect different animal hosts, and among laboratory animals, the 

 guinea-pig is very susceptible to infection with C. ovis, but relatively resistant 

 to C. pyogenes. There are also cultural differences. G. pyogenes liquefies gelatin 

 rapidly and constantly, C. ovis slowly and irregularly. On a medium containing 

 blood serum C. pyogenes gives small dewdrop colonies, which slowly enlarge and 

 become granular in the centre. C. ovis gives colonies that are circular, 

 umbonate and opaque, with a tendency to develop a yellowish pigment. Both 

 organisms form a filtrable toxin. The toxin of C. pyogenes reaches its maximum 

 concentration in culture after 48 hours at 37° C. (Lovell 1937, 1944), that of C. ovis 

 in about 5 days (Carne 1940). Lovell finds that the toxin of C. pyogenes is appar- 

 ently identical with the hsemolysin ; but the toxin of C. ovis, according to Carne 

 (1939), is unrelated to the hsemolysin. It would appear that the toxins of the 

 two organisms are distinct ; the results of cross-protection tests with antitoxin 

 are, however, still awaited. 



An organism that has sometimes been confused with C. pyogenes is C. equi, 

 which was isolated by Magnusson (1923) in Sweden from foals affected with pyaemia. 



