It has been known that H. pylori isolates obtained from different individuals show substantial genetic and phenotypic diversity. Strain variation also has been observed within a single patient. In this study, diversity of H. pylori antibiotics resistance pattern within 10 dyspeptic patients was evaluated by agar dilution method.

Gastric biopsies from 10 patients were cultured on selective brucella blood agar and incubated microaerobically for 5-7 days. Four single colonies per patient were picked from the primary H. pylori culture plates and subcultured to obtain pure H. pylori isolates. Antibiotic susceptibility of primary culture and pure H. pylori isolates to metronidazole (MTZ), clarithromycin (CLR), amoxicillin (AMX), tetracycline (TET) and furazolidone (FRZ) was assessed by agar dilution method.

In all ten patients, results of susceptibility test to TET, AMX and CLR for primary H. pylori culture and related four pure isolates were consistent. However in three patients there was difference between primary and pure cultures of H. pylori in respect to resistance /sensitivity to MTZ and FRZ. In patient one, primary culture was resistant to MTZ and sensitive to FRZ, however two single colonies were sensitive to MTZ and two colonies were resistant to FRZ. In patient two, primary culture was resistant to MTZ, however, one single colony was sensitive. In patient three, primary culture was sensitive to MTZ and FRZ, however two colonies were resistance to MTZ and one colony was resistant to FRZ.

According to our results, both sensitive and resistance H. pylori isolates may be simultaneously present in the same stomach. Co-existence of H. pylori strains with different antibiotic resistance pattern could be a pitfall in all antibiogram-based studies and must be considered to design eradication treatment strategies.