Extended Data Fig. 9: Exchanging ampicillin for kanamycin to limit gut-luminal growth of the donor does not affect the overall plasmid-transfer kinetics, and faecal bacteria-population sizes of intravenously infected mice.

Relates to Fig. 4. a–d, Mice were orally infected with SL1344 P2^cat (Sm^R and Cm^R) as a donor, and 14028S aphT (Kan^R and Amp^R) as a recipient after antibiotic treatment. Mice were either treated with ampicillin in the drinking water until day 15 (normal protocol as in Fig. 1b), day 8 (when the recipient is added) or kanamycin until day 8. a, Donor populations enumerated after a gentamicin protection assay on caecal tissue of mice, in which ampicillin is maintained until day 15 (solid blue circles, n = 15 singly housed mice from 5 independent experiments; data taken from Fig. 1d), ampicillin is removed on day 8 (blue circles with pink fill, n = 3 singly housed mice from 1 experiment) or kanamycin is used until day 8 (blue circles with yellow fill, n = 3 singly housed mice from 1 experiment). Median indicated by solid line. b, Proportion of transconjugants (transconjugant population size divided by the sum of recipients and transconjugants) is shown for the groups receiving ampicillin treatment until day 15 (solid black circles, grey bars indicate median; n = 15 singly housed mice from 5 independent experiments; data taken from Fig. 1c), ampicillin treatment until day 8 (black circles with pink fill, pink bars indicate median; n = 3 singly housed mice from 1 experiment), and kanamycin treatment until day 8 (black circles with yellow fill, yellow bars indicate median; n = 3 singly housed mice from 1 experiment). c, d, Faecal loads of donors (blue, Sm^R and Cm^R), recipients (green, Kan^R) and transconjugants (red, Cm^R and Kan^R) were determined by selective plating on MacConkey agar. c, Mice treated until day 8 with ampicillin. d, Mice treated until day 8 with kanamycin. In a–d, the black dotted line indicates the detection limit for donors and transconjugants. Green dotted line indicates the detection limit for recipients. The detection limit is higher for recipients once transconjugants reach a density of >10⁸ CFU per gram of faeces. Before this happens, recipients can be found below the detection limit; the black dotted line should then be considered as the detection limit. e, Faecal bacterial-populations sizes of mice in Fig. 4e, f (S. Typhimurium donor and E. coli recipient in the intravenous model). Faecal loads of donors (blue, Sm^R and Amp^R), recipients (green, Kan^R) and transconjugants (red, Kan^R and Amp^R) were determined by selective plating on MacConkey agar. Black dotted line indicates the detection limit for donors and transconjugants. Green dotted line indicates the detection limit for recipients. The detection limit is higher for recipients once transconjugants reach a density of >10⁸ CFU per gram faeces. Before this happens, recipients can be found below the detection limit; the black dotted line should then be considered as the detection limit. Blue lines connect medians of donor populations; red lines connect medians of transconjugant populations.

Source data