Geographically distinct North-East Indian strains are highly sensitive to clarithromycin but are levofloxacin resistant.

Purpose: Helicobacter pylori causes various gastro-intestinal diseases. Antibiotic resistance to commonly used antibiotics for the treatment of H. pylori infection is the major cause for treatment failure. The aim of this study is to determine the antimicrobial susceptibility pattern for clarithromycin and levofloxacin and find the evolutionary relationship of the partial sequence of 23S rRNA and gyraseA gene of H. pylori by phylogenetic analysis.

Materials And Methods: A total of 46 H. pylori strains were tested for clarithromycin and levofloxacin susceptibility pattern and phylogenetic tree were reconstructed by PhyML software.

Results: In this study, we observed that only 6.5% of North-East Indian H. pylori strains were resistant for clarithromycin showing mutation at A2143G and T2182C positions of 23S rRNA gene. Resistance for levofloxacin was observed in 89.1% of the H. pylori strains showing mutations at asparagine to lysine at 87 and aspartic acid to glycine/tyrosine/asparagine at 91 positions of gyraseA gene. The phylogenetic tree of the partial sequence of 23S rRNA and gyraseA gene depicts that the North-East Indian strains falls in different cluster when compared to other countries.

Conclusions: Resistance for clarithromycin was less in North-East Indian strains but high for levofloxacin indicating that first-line therapy may be best and effective for eradication of H. pylori in this region. This study is the first report that showed antibiotic susceptibility pattern for clarithromycin and levofloxacin by mutation analysis. By partial sequencing of 23s rRNA and gyraseA gene, we found that North-East Indian strains are geographically distinct.