Omeprazole may exert both a bacteriostatic and a bacteriocidal effect on the growth of Helicobacter pylori (NCTC 11637) in vitro by inhibiting bacterial urease activity.

Abstract

Aims-To assess the potential antibacterial eVect of omeprazole, a benzimidazole proton pump inhibitor, on the growth of Helicobacter pylori in vitro and to evaluate the eVect of this compound on bacterial urease activity. Methods-The growth of H pylori was observed in liquid culture in the presence and absence of omeprazole (0.8 mg/ml). Urease activity was evaluated in aliquots removed from two hour cultures by monitoring the initial change in absorbency at 560 nm in the presence of 0.02% phenol red. Results-The minimum inhibitory concentration of omeprazole against H pylori was 0.8 mg/ml. The concentration of omeprazole required to inhibit growth was dependent on inoculum density: omeprazole (0.8 mg/ml) prevented growth from a 1 × 10 6 cfu/ml inoculum, but not from the higher inocula of 10 7 or 10 8 cfu/ml. This is the first study to demonstrate that omeprazole exerts a bacteriocidal eVect against low bacterial densities and a bacteriostatic eVect when bacterial density is high. When used at the onset of growth, this concentration of omeprazole has a bacteriocidal eVect after four hours, although it exerts a bacteriostatic eVect when added to cultures after the exponential phase. Bacterial urease activity is competitively inhibited by omeprazole in a dose dependent manner. Conclusion-The results suggest that omeprazole exerts both a bacteriocidal and a bacteriostatic eVect against H pylori and competitively inhibits bacterial extracellular urease activity (J Clin Pathol 1998;51:220-224)

Gastric Transitional Zones, Areas whereHelicobacterTreatment Fails: Results of a Treatment Trial Using the Sydney Strain Mouse Model

“…H. pylori SS1 was responsive to all antimicrobials tested in vitro. The MICs were well within the range found for other sensitive strains (2,3,6,15,18,34), indicating that H. pylori SS1 does not have primary resistance to any of these treatments. Furthermore, treatment regimens and dosages, extrapolated from the MACH human trials (27,28), produced effects on infected mice similar to those seen in humans.…”

Antitubercular specific activity of ibuprofen and the other 2-arylpropanoic acids using the HT-SPOTi whole-cell phenotypic assay

“…This densitydependent antibacterial effect has been previously observed for omeprazole against Helicobacter pylori, being bactericidal when incubated from the start of the culture, but being bacteriostatic if added to the exponential-phase culture. 42 It remains possible that several antibacterial drugs show this behaviour, a phenomenon which remains underexplored.…”

In vitro Antagonism of Rabeprazole and Metronidazole upon Clinical Isolates of <i>Helicobacter pylori</i>

“…In the past decade, large numbers of reports were published showing the antibacterial activity of PPI against H. pylori, and various mechanisms of action were proposed, like urease inhibition, membrane damage or decreasing motility [6,16,17] . The result presented also suggests that antibacterial activity of the PPI should be kept in mind when selecting therapeutic strategies for eradication of H. pylori infection, especially when failures in the initial therapy occur.…”