Survival of orally administered E. coli K 12 in alimentary tract of man.

Abstract

VIEWS have recently been expressed that some aspects of genetic engineering research should not be allowed to continue because of their possible dangers to human health1,2. For example, objection has been taken to the laboratory practice of incorporating genetic regions of foreign DNA in bacterial plasmids and introducing them into organisms whose normal habitat is the alimentary tract, because such organisms may accidentally gain access to the alimentary tract of man, colonise it and/or transmit the plasmids during conjugation to the resident intestinal flora. Consequently, we have investigated this matter in regard to Escherichia coli K12, the intestinal organism most frequently used as the recipient of plasmids into which foreign DNA is incorporated, using a human volunteer in whose alimentary tract transfer of plasmids coding for antibiotic resistance (R factors) had previously been demonstrated following the consumption of wild strains of antibiotic-resistant E. coli3. Even when much higher concentrations of E. coli K12 organisms than would be expected to be accidentally consumed in a laboratory were taken, they did not colonise the alimentary tract but organisms of some strains survived better than others; no evidence of transfer of plasmids from these K12 organisms to the resident E. coli of the alimentary tract was found.