Molecular detection of mutations involved in Helicobacter pylori antibiotic resistance in Algeria.

OBJECTIVES

In Algeria, there are limited data regarding the pattern of Helicobacter pylori primary antibiotic resistance. The aim of this study was to evaluate the primary resistance of H. pylori to clarithromycin, ciprofloxacin, tetracycline and rifampicin and to determine the molecular mechanisms involved in the resistance.

METHODS

Two hundred and seventy Algerian adults who had never received H. pylori treatment were enrolled in this study. Human biopsies were obtained for culture and antimicrobial susceptibility testing was performed by Etest for clarithromycin, ciprofloxacin, tetracycline and rifampicin. Real-time fluorescence resonance energy transfer (FRET)-PCR was also performed in all cases to assess primary clarithromycin resistance and point mutations involved, real-time PCR was used to detect mutations involved in tetracycline primary resistance and sequencing of the QRDR of gyrA was performed to detect mutations involved in quinolone resistance.

RESULTS

No resistance to rifampicin was detected. Resistance to clarithromycin and ciprofloxacin was found in 29.7% and 17.9%, respectively. Results of real-time FRET-PCR showed that A2143G was the most frequent point mutation, A2142C was not found and 42 patients (15.5%) were infected by both resistant and susceptible genotypes. Only two isolates were resistant to tetracycline and exhibited an A926G mutation. Four mutations were found to be responsible for resistance to ciprofloxacin [N87K (44.73%), D91N (23.68%), N87I (18.42%) and D91G (7.89%)].

CONCLUSIONS

Local data regarding the primary resistance of H. pylori to clarithromycin, ciprofloxacin, tetracycline and rifampicin and the main genetic mutations involved in the resistance are necessary for a periodic evaluation of antibiotic consumption and new therapeutic strategies in Algeria.