[Contribution of molecular biology to typing: Methodological over view.]

Molecular biology yielded universal typing methods. However, different methods have different applications. Multilocus enzyme electrophoresis allows precise population genetics studies. Random amplification is useful for quickly comparing a few strains. Pulse field gel electrophoresis, which is more discriminating than ribotyping, is indicated for the study of epidemics which do not last more than a few months. Ribotyping, which gives most stable types, is indicated for tracing clones world-wide and for many years. Automatization of key experimental steps and computer-aided interpretation are essential for an objective comparison of many strains. Databases of molecular typing patterns are in completion.