title: Characterization of complement resistance in Escherichia coli conferred by the antibiotic resistance plasmid R100.
abstract: We have examined the effect of the antibiotic resistance plasmid, R100, on the complement (C) mediated killing of Escherichia coli K-12 strains. The viabilities, in dilute normal rabbit serum (NRS), of 5 such strains were compared with the viabilities of the same strains harboring R100. For 1 strain, J6-2, we also measured the effect of R100 on viability in normal human serum (NHS) and in guinea pig serum (GPS); in NRS, NHS,and GPS devoid of classical C pathway activity; and in NHS devoid of alternative pathway activity. Finally, we compared the depletion of individual complement components in sera exposed to J6-2 and J6-2 harboring R100. Our results demonstrate that 1) R100 renders E. coli K-12 resistant to killing by NRS, NHS, and GPS; 2) the level of resistance, which ranges from 30- to 10,000-fold, is strain dependent and serum dependent; 3) R100 inhibits killing by both the classical and alternative C pathway. Resistance appears to involve a disruption on the C pathway subsequent to the activation of C5.
mesh_terms: D000818:Animals; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D003165:Complement System Proteins; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000276:immunology*; D006168:Guinea Pigs; D006801:Humans; D010957:Plasmids; D011817:Rabbits
chemical_list: D003165:Complement System Proteins