Background: Diversity in metronidazole susceptibility and genotypes of Heli
cobacter pylori have been reported with varying results in different areas.
Aims: To investigate the prevalence of multiple strain infection in a sympt
omatic Chinese population and to determine the metronidazole susceptibility
pattern and genotypic characteristics of these infecting strains.
Methods: Gastric biopsies from antrum, body and cardia were taken during up
per endoscopy in symptomatic patients referred to our department. Pooled cu
ltures and single colony isolates were obtained and tested for metronidazol
e susceptibility and random amplified polymorphic DNA (RAPD) fingerprint pa
Results: A total of 461 isolates were successfully cultured from 46 patient
s. Fifty-seven per cent of subjects had metronidazole-resistant strains. Am
ong them. 77% carried a mixture of sensitive and resistant strains, nan-uni
formly distributed in the gastric mucosa. Mixed genotypes were found by RAP
D typing in 24% of subjects. These did not correlate with the metronidazole
Conclusion: H. pylori infections with mixed metronidazole sensitive/resista
nt strains and mixed genotypes are common in Hong Kong. This makes it prude
nt to use bacterial strains from several biopsy sites when testing for trai
ts such as drug resistance or virulence in relation to disease.