OASTRO-INTESTINAL FLORA OF NORMAL INFANTS 0C)3 
THE GASTRO-INTESTINAL FLORA OF NORMAL INFANTS, 
ADOLESCENTS AND ADULTS. 
The fetal intestinal contents, the meconinm, 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 })y 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 luxm-iant when the infant 
is exposed to relatively uncleanly surroundings than when the reverse 
is the case. Escherich^ and others have called attention to the occur- 
rence of a rather large bacillus in the meconium, possessing a terminal 
spore closely resembling B. tetani. This organism, known as the 
Kopfchen bacillus, has been identified by some observers as B. putriii- 
cus of Bienstock;- 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 B. aerogenes capsulatus and mem- 
bers of the B. mesentericus group are the best known. B. coli, B. pro- 
teus, B. lactis aerogenes and Micrococcus ovalis^ 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- 
forming types disappear for the most part and rather abruptly, and 
the coccal forms and Gram-negative bacilli of the colon aerogenes type 
diminish relatively, but never quite disappear. Simultaneously rather 
long, thin bacilli, occurring singly, in pairs, or in groups with their 
axes parallel, become strikingly prominent. These bacilli are fre- 
quently slightly curved and occasionally their ends are somewhat 
attenuated. Typically they are Gram-positive and stain uniformly, 
but in many instances they exhibit a central Gram-positive granule 
in an othervvise Gram-negative rod, presenting the "punctate" appear- 
ance described by Escherich.^ Occasionally the cytoplasm of these 
organisms is collected into small, round or oval granules which stain 
1 Escherich: Darmbacterien des Saiiglings, Stuttgart, 1886, p. 9. 
2 Arch. f. Hyg., 1899, 36 335; ibid., 1901, 39, 390. 
3 Micrococcus ovalis (Escherich: Loc. cit., (>. 89) appears to be identical with the 
enterocoque of the French writers, with Streptococcus lacticus of Kruse (Centralbl. f. 
Bakteriol., orig., 1903, 34, 737) and Streptococcus enteritidis of Hirsch (ibid., 1897, 22, 
369) and Libman (ibid., 1897, 22, 376). See also Dible (Jour. Pathol, and Bacteriol., 
1921. 24, 1) ; Kendall and Haner: Jour. Infec. Dis., 1924, 35, 67. 
* Loc. cit. 
