Antibacterial activities of beta-lactamase inhibitors associated with morphological changes of cell wall in Helicobacter pylori

Background. Recent study has demonstrated that β‐lactamase inhibitors including clavulanate, sulbactam and tazobactam have an vitro antibacterial effect on Helicobacter pylori. Here we describe the relationship between viability and cell profiles of H. pylori exposed to β‐lactamase inhibitors and some antibiotics in a short‐time course. Materials and methods. The antibacterial effects of β‐lactamase inhibitors including clavulanate, sulbactam and tazobactam on the bacterial viability of and morphological changes in H. pylori ATCC43504 were examined. Results. The β‐lactamase inhibitors such as clavulanate and sulbactam alone decreased the viable counts of H. pylori, depending on the antibiotic concentrations. Exposure to these β‐lactamase inhibitors resulted in morphological changes of cell shape, cell‐wall disintegration and cell lysis. Among these β‐lactamase inhibitors, clavulanate was the most active, causing a decrease in viable counts and morphological changes such as short filamentous to sphaeroplast formation and lysis. One × minimum inhibitory concentration (MIC) of amoxicillin plus 1 × MIC of clavulanate decreased viable counts effectively compared with 1 × MIC of amoxicillin or 1 × MIC of clavulanate alone, and induced morphological changes of cell shape and cell wall. Conclusion. Our results suggest that the β‐lactamase inhibitors alone have concentration‐dependent antibacterial activities against H. pylori and affect the morphology of the cell shape and the cell wall in vitro.