140-MDA PLASMIDS OF ESCHERICHIA-COLI AND SHIGELLA-FLEXNERI 5 DO NOT INFLUENCE PHAGOCYTOSIS

Enteroinvasive Escherichia coli (EIEC) and Shigella flexneri possessing a 140-megadalton (MDa) plasmid are capable of invading intestinal epithelial cells and causing dysentery. To determine if this plasmid affected phagocytosis of the organisms by leukocytes, we studied the in vitro phagocytosis of isogenic pairs of EIEC and S. flexneri 5 which differed only in the presence or absence of the 140-MDa plasmid. In addition five EIEC strains containing 140-MDa plasmids as well as one non-enteroinvasive E. coli strain possessing a 120-MDa plasmid were studied. The 140-MDa plasmid did not affect phagocytosis of these bacteria by normal human blood neutrophils or monocytes.