Mucoid Bacterium Coli in Feces of Normal Subject

Abstract

Theobald Smith was first to call attention to colon bacilli so similar in colony form to B. aerogenes as to be indistinguishable morphologically. Smith's culture “29” derived from a sample of spring water. Mucoid forms of colon bacilli have since been reported under a variety of conditions. Kuwaraba reported a cap-sulated organism from panophthalmitis at first identified as Fried-lander's bacillus, but later as B. coli. Revis contaminated soil with feces and after several months obtained mucoid colon bacilli which at 20°C. produced slimy colonies as much as half an inch in diameter. These forms reverted readily to typical colon bacilli. Bordet and Ciuca obtained mucoid “modified B. coli” by the action on the colon bacillus of a guinea pig peritoneal exudate produced by injecting B. coli. Gratia confirmed the wrork of Bordet and Ciuca. He also produced non-mucoid variants by aging a normal culture. Gory obtained mucoid coli by the bacteriophagic action of filtered sewage. Theobald Smith and associates in work on pathogenic B. coli from bovine sources (scours) dealt with mucoid forms and derivatives therefrom. Parr and Caldwell recovered mucoid forms of various members of the colon-aerogenes group, including coli, from water samples from pumps near bored latrines. Lawson reports the recovery of mucoid colon bacilli from diarrheal stools of infants. Dominick encountered mucoid coli in well water regularly receiving chlorine. Furthermore the colon bacillus is ordinarily noncapsulated except by special technique, Churchman and Eme-lianoff. We here report the occurrence of encapsulated B. coli, giving rise to large, moist mucoid colonies on plate culture, derived from the feces of a normal, adult male. During 1932-33, 156 strains were isolated on Endo's agar from 16 fresh fecal suspensions in sterile saline in a preliminary attempt to determine the relative percentages of the different members of the colon-aerogenes group appearing on a medium on which all such members grow well. Unexpectedly it was found that on most platings all colonies were devoid of metallic sheen and were larger, more raised and more moist than the classical colon bacilli. A few times these mucoids were mixed on the plates with typical forms and once no mucoid types were encountered. Of the 156 isolations, 91% were B. coli. The mucoid colonies were made up of very short, encapsulated Gram negative bacilli which did not liquefy gelatin nor ferment saccharose, but which in all cases fermented dextrose and lactose with production of gas as well as acid were methyl-red positive, produced indol and failed to grow on citrate agar. No H2S was produced. Motility was negative in 24 hr. broth cultures. Flagellar stains have not yet been made. Milk was on first isolation only acidified but on sub-culture coagulated. Broth suspensions remained homogenous. Serological investigations have not yet been undertaken. These forms have thus far maintained their mucoid nature despite manipulation designed to revert them to a non-encapsulated state.