THE GASTRO-INTESTINAL FLORA OF NORMAL INFANTS 581 



tract may become somewhat widely disseminated in restricted areas 

 and appear in the intestinal contents of many individuals without 

 inciting noteworthy symptoms, prior to the appearance of disease in 

 epidemic proportions 1 and with characteristic symptoms. 



THE GASTRO-INTESTINAL FLORA OF NORMAL INFANTS, 

 ADOLESCENTS AND ADULTS. 



The fetal intestinal contents, the meconium, are sterile at birth; 

 the first bacteria appear in the meconium from eighteen to twenty- 

 four hours postpartum. This is a period of adventitious infection 

 during which a variety of bacterial types, largely determined by the 

 environment of the infant, gain entrance to the alimentary canal by 

 way of the mouth or anus and are excreted in the residual embryonic 

 feces. This initial non-characteristic intestinal flora is usually more 

 varied in summer than in winter and more luxuriant when the infant 

 is exposed to relatively uncleanly surroundings than when the reverse 

 is the case. Escherich 2 and others have called attention to the occur- 

 rence of a rather large bacillus in the meconium, possessing a terminal 

 spore closely resembling Bacillus tetani. This organism, known as the 

 Kopfchen bacillus, has been identified by some observers as Bacillus 

 putrificus of Bienstock; 3 it has not been studied culturally, however, 

 and this identification cannot be regarded as final. Other spore- 

 forming bacteria, both aerobic and anaerobic, are also usually present 

 in the meconium at this period. Of these Bacillus aerogenes capsulatus 

 and members of the Bacillus Mesentericus Group are the best known. 

 Bacillus coli, Bacillus proteus, Bacillus lactis aerogenes and Micro- 

 coccus ovalis 4 also occur commonly. 



The initial period of adventitious bacterial infection of the intestinal 

 contents merges more or less imperceptibly through a transitional 

 stage to the period of dominance of the characteristic infantile intes- 

 tinal flora, which becomes settled usually about the third day post- 

 partum. At this time the breast milk diet of the nursling is well 

 established and the intestinal tract is permeated with it. The bacteria 

 throughout the alimentary canal become more numerous, the spore- 



1 Kendall, Boston Med. and Surg. Jour., 1915, clxxii, 851. 



2 Escherich, Darmbakterien des Saiiglings, Stuttgart, 1886, p. 9. 



3 Arch. f. Hyg., 1899, xxxvi, 335; ibid., 1900, xxix, 390. 



4 Micrococcus ovalis (Escherich, loc. cit., p. 89) appears to be identical with the 

 enterocoque of the French writers, with Streptococcus lacticus of Kruse (Centralbl. f. 

 Bakt., Orig., 1903, xxxiv, 737) and Streptococcus enteriditis of Hirsch (ibid., 1897, xxii, 

 369), and Libman (ibid., 1897, xxii, 376). 



