Antibiotic stress affects the secretion and physicochemical features of extracellular vesicles produced by Helicobacter pylori.

BACKGROUND

Bacterial extracellular vesicles (EVs) may reduce the effectiveness of various antimicrobials; however, the impact of antibiotics on the secretion and properties of EVs produced by Helicobacter pylori has not been established.

METHODS

Using clinical H. pylori strains and culture in EV-depleted media, the influence of ¼ × MIC of clarithromycin, metronidazole and levofloxacin on EV features was determined. Physicochemical properties of EVs were measured using nanoparticle tracking analysis and dynamic light scattering. Determination of fatty acid profiles of EVs and bacterial cells was performed with GC triple-quadrupole tandem MS. Bacteria and EVs were observed by scanning and transmission electron microscopy, respectively.

RESULTS

Antibiotic stress induced in H. pylori affects the secretion intensity and physicochemical features of EVs secreted by this bacterium in a strain- and antibiotic-dependent manner. Exposure to ¼ × MIC of metronidazole or levofloxacin increased the secretion of EVs and contributed to significant changes in their fatty acid profile, whereas treatment with ¼ × MIC of clarithromycin did not induce such changes. Regardless of the culture conditions and the strain analysed, the existence of a conservative process of selective packaging of C17:0 fatty acids into EVs and a substantial limitation of this phenomenon for C14:0, C18:1 and C19c:0 was demonstrated.

CONCLUSION

This is the first study showing the modulatory effect of antibiotic stress on the secretion and physicochemical features of EVs produced by H. pylori, as well as the first to suggest the involvement of EVs in maintaining the appropriate membrane fatty acid composition of this bacterium.