Fig 4. In vivo cure of antibiotic resistance plasmids.

CTX^STET^S E. coli (green) were detected in all four groups of mice at the start of the experiments (A-D). All groups of mice were then fed bacteria carrying CTX^R target plasmid (pEl1573 or pJIE512b) with CTX, days 4–6 (red lines, A-D) and CTX^R E. coli (red) appeared. Two groups of mice (A, B) then received the corresponding TET^R interference plasmid (pJIMK46 or pJIMK56) with TET, days 8–10 (blue lines) resulting in a decline in number of CTX^R E. coli. TET^R E. coli (blue) also appeared and then declined. CTX^STET^S E. coli appeared again after curing of target and interference plasmids but were killed by CTX administered on days 23–24 (black lines, A, B). CTX^R E. coli persisted to end of protocol in control groups that did not receive interference plasmid (C, D).