Effects of combining extracts (from propolis or Zingiber officinale) with clarithromycin on Helicobacter pylori

Propolis and Zingiber officinale have been shown to be specifically targeted against Helicobacter pylori strains, to possess antiinflammatory, antioxidant and antitumoral activity and to be used in traditional medi- cine for the treatment of gastrointestinal ailments. Considering that these natural products could potentially serve as novel therapeutic tools also in combination with an antibiotic, the aim of this work was to evaluate their effect when combined with clarithromycin on clinical H. pylori isolates (n = 25), characterized in respect to both clarithromycin susceptibility and the presence of the cagA gene. The results showed that the com- binations of propolis extract ++ ++ + clarithromycin and Z. officinale extract ++ ++ + clarithromycin exhibited improved inhibition of H. pylori with synergistic or additive activity. Interestingly, the susceptibility to combinations was significantly independent of the microbial clarithromycin susceptibility status. Only one H. pylori strain showed antagonism towards the Z. officinale extract +clarithromycin combination. The data demonstrate that com- binations of propolis extract + clarithromycin and Z. officinale extract + clarithromycin have the potential to help control H. pylori-associated gastroduodenal disease.