Explanations for high rates of eradication with triple therapy using metronidazole in patients harboring metronidazole-resistant Helicobacter pylori strains

Abstract

In 4 of 17 Helicobacter pylori strains obtained from antral biopsy samples, the registered primary resistance (MIC, >32 g/ml) appeared to be nonstable after prolonged microaerophilic incubation. In all resistant strains tested, susceptibility could be obtained when culture under normal microaerophilic conditions was preceded by a period of anaerobic incubation. Both of these findings may explain the observed discrepancy between the results of in vitro susceptibility tests and the eradication obtained in vivo.

Antibacterial Activities of Liposomal Linolenic Acids against Antibiotic-Resistant Helicobacter pylori

“…31, 32 Similar to metronidazole, FFAs have also been hypothesized to inhibit bacteria growth through mechanisms that alternate cell survival signaling pathways. For example, it has been suggested that FFAs may enter the cells and inhibit bacterial growth by creating an acidic environment in cytoplasm that damages pH-sensitive intracellular enzyme activities or amino acid transports.…”

Antibiotic resistance in Helicobacter pylori infection

“…The activation of an anaerobic metabolic pathway which does not function under microaerobic conditions could be the cause and would also explain the apparent non-stable resistance 12 , since the atmosphere of incubation is not fully controlled during subculture of the strains.…”

Helicobacter pylori in Children: Acquisition of Antimicrobial Resistance after an Initial Course of Treatment

“…Secondary resistance implies that some strains are able to develop resistance in vivo (1). However, the apparent loss of resistance to metronidazole observed for one isolate may be explained by any one of several phenomena, such as contamination with a new strain or the unreliable results of antimicrobial susceptibility testing under microaerophilic conditions, as previously described (10). Colonization with a clarithromycin-resistant strain of H. pylori in patients with no history of clarithromycin exposure has been previously reported (7).…”