Fig. 5.

Intestinal density of S. Tm plasmid donors correlates with E. coli transconjugant frequency. Streptomycin-treated conventional mice (n = 20) were coinfected with mixtures of Ec^{8178_cured amp} (recipient; amp^R), S. Tm^tet p2^Δcib (donor; tet^R; plasmid p2: kan^R) and increasing amounts of S. Tm^wt p2^{ΔoriTnikAΔcib} (competitor; cm^R) at no (n = 4), 10-fold (n = 3), 100-fold (n = 3), 1,000-fold (n = 3), 10,000-fold (n = 3), and 100,000-fold (n = 4) excess over the donor strain (total of 5 × 10⁷; intragastrically). The density of the S. Tm donor (x axis) was plotted against E. coli transconjugant frequencies (fraction of amp^R kan^R E. coli of total amp^R E. coli; y axis) as determined in the feces at day 1 p.i. (A) and cecal contents at day 4 p.i. (B). A linear relationship between cfu and transconjugant frequency could be predicted by linear regression analysis (P < 0.05).