Paracolon and Proteus bacilli in the feces of healthy infants

Abstract

Summary A study of the normal bacterial flora (gram-negative, enteric bacilli) of the intestine of healthy infants under 1 year of age was carried out, utilizing recently introduced selective culture media, including Salmonella-Shigella and desoxycholate-citrate agar, and the enriching fluid of Bangxang and Eliot. The results obtained were as follow: 1. Only seventeen, or 34 per cent, of the infants harbored solely Bacillus coli, Bacillus aerogenes and intermediates in the intestinal tract. 2. Thirty-three, or 66 per cent, harbored also other gram-negative, enteric bacilli. 3. Paracolon bacilli were recovered from eleven, or 22 per cent, of the infants. In four instances paracolon bacilli were found together with Proteus ammoniae, Proteus morganii, Bacillus pyocyaneus, and Bacillus alkalescens, respectively. 4. Proteus bacilli were present in twenty, or 40 per cent, of the cases. Among the species encountered were typical and atypical strains of Proteus vulgaris, Proteus ammoniae, and Proteus morganii. In seven out of the twenty instances one species of proteus was found in combination with other proteus types or different enteric bacilli. 5. Bacillus coli mutabilis was found in two; Bacillus alkalescens, in two; and Bacillus pyocyaneus, in four instances. 6. Of the culture media used Salmonella-Shigella agar proved to be superior to any other culture medium in the isolation of these microorganisms, particularly of the various proteus bacilli. 7. Data on the incidence of paracolon and proteus bacilli in the intestinal tract of healthy infants based upon older and obsolete cultural methods require revision.