Fig. 5.

Heat treatment does not prevent OMV-mediated protection of H. pylori against clarithromycin. Bacteria were suspended in BHI broth and exposed to 5 µg clarithromycin ml⁻¹ (black bars) with and without 25 µg purified OMVs ml⁻¹. The OMV label indicates that normal purified OMVs were added. OMV + heat indicates that the OMVs were pre-treated with heat (80 °C for 10 min) before use in the assay. After 3 h incubation at 37 °C under microaerobic conditions, the surviving bacteria were quantified by serial dilution and plating. Data are expressed as c.f.u. ml⁻¹ (a) and percentage survival compared to untreated bacteria (b). Untreated bacteria (white bar) were incubated in BHI broth without clarithromycin and OMVs. Mean values ± sd from three independent replicates are shown. The limit of detection, 33 c.f.u. ml⁻¹, is indicated by a dashed line. Addition of 25 µg OMVs ml⁻¹ significantly protected H. pylori against clarithromycin treatment (**P<0.01, one-way ANOVA with Tukey’s multiple comparison tests) and there was no significant difference in the protective effects of heat-treated versus non-heat-treated OMVs. ns, No significant difference.