Microbial typing is a useful tool in clinical epidemiology for defining the
source and route of infection, for studying the persistence and reinfectio
n rates, clonal selection in the host and bacterial evolution. Phenotypic m
ethods such as biotyping, serotyping and hemagglutinin typing have little d
iscriminatory power compared to genotypic methods concerning the typing of
Helicobacter pylori. Therefore great efforts have been made to establish us
eful molecular typing methods. In this context, the most frequently used ge
notypic methods are described based on our own experience and the literatur
e: (1) restriction endonuclease analysis, (2) endonuclease analysis using p
ulsed-field gel electrophoresis, (3) ribotyping, (4) polymerase chain react
ion (using either random primers or repetitive DNA sequence primers), and (
5) polymerase chain reaction-restriction fragment length polymorphism analy
sis of e.g. the urease genes. Furthermore, reproducibility, discriminatory
power, ease of performance and interpretation, cost and toxic procedures of
each method are assessed. To date no direct comparison of all the molecula
r typing methods described has been performed in the same study with the sa
me H. pylori strains. However, PCR analysis of the urease gene directly on
suspensions of H. pylori or gastric biopsy material seems to be useful for
routine use and applicable in specific epidemiological situations. (C) 1999
Federation of European Microbiological Societies. Published by Elsevier Sc
ience B.V. All rights reserved.