Molecular methods for typing ofHelicobacter pyloriand their applications

Abstract

Microbial typing is a useful tool in clinical epidemiology for defining the source and route of infection, for studying the persistence and reinfection rates, clonal selection in the host and bacterial evolution. Phenotypic methods such as biotyping, serotyping and hemagglutinin typing have little discriminatory power compared to genotypic methods concerning the typing of Helicobacter pylori. Therefore great efforts have been made to establish useful molecular typing methods. In this context, the most frequently used genotypic methods are described based on our own experience and the literature: (1) restriction endonuclease analysis, (2) endonuclease analysis using pulsed-field gel electrophoresis, (3) ribotyping, (4) polymerase chain reaction (using either random primers or repetitive DNA sequence primers), and (5) polymerase chain reaction-restriction fragment length polymorphism analysis 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 molecular typing methods described has been performed in the same study with the same 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.

Restriction Fragment Length Polymorphism of Urease C and Urease B Genes of Helicobacter pylori Strains Isolated from Brazilian Patients with Peptic Ulcer and Chronic Gastritis

“…One of the main proteins of H. pylori is urease and the genes encoding this and their accessory proteins have been studied for PCR because these genes are highly conserved in H. pylori [15][16][17]. Analysis of smaller fragments of the urease C and urease B genes using the restriction enzymes HaeIII and MboI demonstrated that the genomic structure of H. pylori was highly diverse [18].…”