Anti-Helicobacter pylori activity of ethoxzolamide

Abstract

Ethoxzolamide (EZA), acetazolamide, and methazolamide are clinically used sulphonamide drugs designed to treat non-bacteria-related illnesses (e.g. glaucoma), but they also show antimicrobial activity against the gastric pathogen Helicobacter pylori. EZA showed the highest activity, and was effective against clinical isolates resistant to metronidazole, clarithromycin, and/or amoxicillin, suggesting that EZA kills H. pylori via mechanisms different from that of these antibiotics. The frequency of single-step spontaneous resistance acquisition by H. pylori was less than 5 Â 10 À9 , showing that resistance to EZA does not develop easily. Resistance was associated with mutations in three genes, including the one that encodes undecaprenyl pyrophosphate synthase, a known target of sulphonamides. The data indicate that EZA impacts multiple targets in killing H. pylori. Our findings suggest that developing the approved anti-glaucoma drug EZA into a more effective anti-H. pylori agent may offer a faster and cost-effective route towards new antimicrobials with a novel mechanism of action.

Antibacterial activity of ethoxzolamide against Helicobacter pylori strains SS1 and 26695

“…Indeed, other sulfonamides (BTB06061 and HTS04781) have been previously shown to inhibit H. pylori UppS with IC 50 in the micromolar range [21]. Furthermore, out of the two mutations found in uppS, one (Glu173Lys) changes a residue in the enzyme active site [11], which supports the notion that EZA likely acts as a competitive inhibitor of UppS by mimicking its natural substrate, transition state or product. Although the uppS gene was not altered in the SS1 mutant resistant to EZA, we have found a mutation in the wzk gene encoding the O-antigen flippase, a protein in the same biosynthetic pathway.…”

“…To date, EZA activity and resistance have been investigated for only one H. pylori strain, P12 [11]. In this study, we have performed a susceptibility and resistance study with H. pylori strains SS1 and 26695.…”

“…Indeed, EZA has been shown to kill H. pylori P12 in vitro [11]. In addition, it was shown to be effective against clinical isolates resistant to conventional antibiotics, suggesting that EZA kills H. pylori via mechanisms different from those of metronidazole, clarithromycin, and amoxicillin.…”

“…These observations suggest that the EZA inhibition of activity of H. pylori carbonic anhydrases likely plays an important role in the mechanism of its antibacterial action, although no spontaneous HpαCA and HpβCA mutants with resistance to EZA have been isolated so far. Furthermore, previous studies showed that in H. pylori strain P12, spontaneous resistance to EZA does not emerge easily [11], suggesting that it may be considered a lead compound for development of an anti-H. pylori drug with a novel mechanism of action. This work emphasized the necessity for further studies of EZA activity against different H. pylori strains.…”

“…It has been previously shown that EZA displays antimicrobial activity against H. pylori strains SS1 (MIC = 0.2 mM, MBC = 0.4 mM) and 26695 (MIC = 0.3 mM, MBC = 0.5 mM) [11]. To enhance our understanding of its bactericidal properties, we assessed time-dependent killing kinetics at concentrations corresponding to 1 × MBC and 2 × MBC.…”