The role of hp1165 gene on the efflux-mediated resistance to tetracycline in clinical isolates of Helicobacter pylori

Tetracycline-resistant (TetR) Helicobacter pylori isolates have emerged in many parts of the world. We have previously demonstrated that among the mechanisms involved in the resistance of H. Pylori to Tet, its active efflux may be an important mechanism. This work, aimed to determine whether presence and/or expression ofhp1165 are associated with efflux-mediated resistance to Tet in clinical strains of H. pylori. Twenty five TetR strains including seven low level-resistant, eight intermediately-resistant, and ten high-level resistant strains/or mutants, of which 21 displayed the active efflux ability for Tet, were investigated. They were screened for the presence of mutation (s) in 16S rRNA at 965-967 position and for the presence of hp1165 gene. Detection of hp1165 gene transcription /or gene expression was performed by RT-PCR Two low-level TetR strains displaying no efflux ability, that contained mutation (s) at 965-967 position of 16S rRNA. Ten out of 21 TetR strains displaying active efflux abilities, that contained hp1165 gene. Their PCR product was similar to that of 26695 standard strains, susceptible to Tet. RT-PCR was positive for five out of them however; their product size was approximately 100 bps smaller than that of 26695 strains. Regarding to the results of PCR and RT-PCR, hp1165 plays a role in the active efflux of Tet in resistant strains. A post-transcriptional regulation step may be involved in the expression of hp1165 gene in TetR strains.   Key words: Helicobacter pylori, tetracycline, resistance, efflux, hp1165 gene.