Genotypic characterization of Salmonella typhi by amplified fragment length polymorphism fingerprinting provides increased discrimination as comparedto pulsed-field gel electrophoresis and ribotyping

Amplified fragment length polymorphism (AFLP) is a recently developed, PCR- based high resolution fingerprinting method that is able to generate comple x banding patterns which can be used to delineate intraspecific genetic rel ationships among bacteria. In the present study, AFLP was evaluated for its usefulness in the molecular typing of Salmonella typhi in comparison to ri botyping and pulsed-field gel electrophoresis (PFGE). Six S. typhi isolates from diverse geographic areas (Malaysia, Indonesia, India, Chile, Papua Ne w Guinea and Switzerland) gave unique, heterogeneous profiles when typed by AFLP, a result which was consistent with ribotyping and PFGE analysis. In a further study of selected S. typhi isolates from Papua New Guinea which c aused fatal and non-fatal disease previously shown to be clonally related b y PFGE, AFLP discriminated between these isolates but did not indicate a li nkage between genotype with virulence. We conclude that AFLP (discriminator y index = 0.88) has a higher discriminatory power for strain differentiatio n among S. typhi than ribotyping (DI = 0.63) and PFGE (DI = 0.74). (C) 2000 Elsevier Science B.V. All rights reserved.