Fig. 3.

Protective effects of OMVs against clarithromycin treatment. H. pylori were incubated for 3 h in the presence of 10 µg clarithromycin ml⁻¹, 100 µg metronidazole ml⁻¹ or 10 µg levofloxacin ml⁻¹. These concentrations of drug were sufficient to significantly reduce bacterial survival (***P<0.001, two-way ANOVA with Dunnett’s multiple comparisons tests versus the untreated control group). The limit of detection, 33 c.f.u. ml⁻¹, is indicated by dashed lines. Supplementation with 25 µg purified OMVs ml⁻¹ improved bacterial survival of clarithromycin and levofloxacin treatment, but not metronidazole. After OMV supplementation, bacterial survival was not significantly different to the untreated control group. Data shown are mean c.f.u. ml⁻¹ ± sd (a) and percentage survival compared to the untreated control group (b) for three independent replicates.