Objective    To evaluate the genetic diversity of 30 Helicobacter pylori isolates from the patients in four cities of China (Beijing

Shanghai

Guangzhou

Chongqing) by the multilocus sequence typing (MLST)

and to find the link between the vacA genotype and sequence type (ST).     Methods    Isolates were randomly recruited from consecutive endoscopy clinics in four cities. An average of 5-6 strains per patient were isolated and eight loci selected for the MLST scheme were amplified and sequenced with primers. The vacA genotype was analyzed by PCR and 3% agarose electrophoresis.     Results    There were totally 28 ST genotypes

most of which are new ST genotypes that have never been found among the database. The most prevalent vacA genotype was s1a/m2 (83.3%)

followed by s1b/m2 (13.0%). In contrast

the s1a/m1 genotype was scarcely present (0%).     Conclusion    The vacA genotype varied for each ST. Our results showed no obvious link between STs and vacA genotypes. As there are little data on human isolates due to the absence of systematic epidemiological investigations of H. pylori in medical laboratories

our research will provide useful information in understanding the epidemiology of H. pylori in China.