THE STREPTOCOCCUS GROUP o()7 
commonly involved.^ Escherich^ and others have described a severe 
type of enteritis, particularly of young children — streptococcus enter- 
itis—which occasionally exhibits an epidemic tendency in the summer 
months.^ Attention has been directed in recent years to severe 
epidemics of septic sore throat^ in which the evidence points to strep- 
tococci transmitted through milk as the etiological agent. The 
type of streptococcus involved has been a subject of controversy, 
but the extensive studies of Smith and Brown^ show clearly that Strep- 
tococcus pyogenes is by far the most common organism found. They 
demonstrated that the streptococcus which is isolated from bovine 
mastitis is not, except possibly in rare instances, a causative favor in 
epidemic sore throat. These appear to be non-virulent for man as a 
rule. On the contrary, hemolytic strains virulent for rabbits are 
probably infective for man. The non-virulent strains resisted an 
exposure to 08° C. for thirty minutes. The virulent strains were killed 
by an exposure of thirty minutes to 60° C. 
Streptococci occur frequently as secondary invaders in diphtheria, 
many gastro-intestinal diseases, and diseases of the lungs, where they 
may be at times even more formidable than the primary infecting 
organism. As Theobald Smith has admirably expressed it, they 
are "organisms of the diseased state." The virulence exliibited by 
streptococci varies considerably, as does the type of lesions they 
excite. This variation in virulence is not at all well understood at the 
present time, but experiments indicate that the site of infection and 
the past history of the organism exercise some influence. Rosenow'' 
has isolated streptococci, using special methods, from the regional 
glands in arthritis, gall-bladders and gastric ulcers. He states that 
the freshly-isolated strains exhibit rather marked tendencies to local- 
ize in the homologous tissues of experimental animals. This specific 
tissue affinity is rapidly lost during cultivation of the organisms in 
artificial media, however. 
Animal .Fviinkel,'^ Petruschky,^ and Koch and Petruschky^ showed 
that the virulence of the same strain of streptococcus varied materially 
according to the conditions of culture, and that the lesions produced 
in rabbits varied likewise; thus the descendants of the same culture 
1 Meyer: Ztschr. f. klin. Med., 1902, 46, 311; Internat. Bcitr. zur inn. Med., 1902, 
2, 443. Philipp: Deutsch. Arch. f. klin. Med., 1903, 76, 150. Poynton and Payne: 
Centralbl. f. Bakteriol., orig., 1902, 31, 502. Cole: Jour. Infec. Dis., 1904, 1, 714. 
Rosenow: Jour. Infec. Dis., 1910, 7, 411; ibid., 1912, 11, 210; Jour. Am. Med. Assn.. 
1913, 60, 1223. 
2 Jahrb. f. Kinderheilk., 1899, 49, 137. 
' Kendall, Day and Bagg: Boston Med. and Surg. Jour., 1913, 169, 741. 
* Davis has described a capsule on the streptococcus of epidemic sore throat, which is 
soon lost in artificial media. Jour. Am. Med. Assn., 1912, 58, 1852. 
5 Jour. Med. Res., 1914, 31, 455. 
6 Jour. Am. Med. Assn., 1913, 60, 1223; 61, 1947; 1914, 63, 1.S35; Jour. Infec. Dis.. 
1915, 16, 240. 
' Centralbl. f. Bakteriol., 1889, 6, 671. 
« Ztschr. f. Hyg., 1896, 23, 142. 
3 Ibid., p. 477. 
