Use of laboratory methods for epidemiology of bacterial infections.

The laboratory plays a significant role in the epidemiologic investigations by the comparative analysis of the bacterial strains involved in the outbr eaks. Recently the use of molecular analysis methods provided better perfor mance than traditionnal phenotypic methods which are still used as prelimin ary tests because of their relatively low cost and technical simplicity. Th ese analyses deal with either the whole chromosome of the bacterium, plasmi ds or particular genes. The classification of these methods runs up against the lack of consensus concerning their nomenclature. A clearer denominatio n based upon the technique responsible for revealing the polymorphisms of t hese various targets, makes it possible to divide these methods in two prin cipal groups: methods of RFLP (based on the fragments resulting from digest ion with restriction enzymes) and methods of AFLP (based on the products of amplification by PCR). The knowledge of the typability of the strains and the qualities of these various methods, particularly their discriminatory p ower, is essential to the accuracy of the laboratory analysis in the invest igations of outbreaks. (C) 2001 Editions scientifiques et medicales Elsevie r SAS.