Properties of Escherichia coli grown in vivo using a chamber implant system

Strains of Escherichia coli were examined for their ability to grow in diffusion chambers implanted into the peritoneal cavities of mice and rabbits. In rabbit chambers E. coli K12 strains grew poorly, whereas isogenic strains harbouring ColV plasmids and wild-type isolates from extra-intestinal infections grew well. The difference was much less marked with strains grown in mouse chambers. Differences in sensitivity to the bactericidal action of human or rabbit serum were found in some cases between organisms of the same strain grown in vivo or in vitro. Host immunoglobulins were bound to the surface of all in vivo bacteria. Comparison of the polypeptide composition of bacterial cell envelope preparations on SDS-PAGE gels revealed differences between in vivo and in vitro grown E. coli growing in vivo may possess properties significantly different from the same organisms growing on laboratory medium.