Fluorescent Amplified-Fragment Length Polymorphism Subtyping of the S almonella enterica Serovar Enteritidis Phage Type 4 Clone Complex

Abstract

ABSTRACT Fluorescent amplified-fragment length polymorphism (FAFLP) analysis, a high-resolution PCR-based genome fingerprinting method, was used to subtype Salmonella enterica serovar Enteritidis phage type 4. This single phage type is responsible for the majority of salmonellosis in Europe. Twenty strains isolated from nine outbreaks, five isolates from sporadic cases of human infection, four strains of poultry origin, and one laboratory-derived strain were comparatively studied by pulsed-field gel electrophoresis (PFGE) and FAFLP analysis. Following macrorestriction with Xba I, PFGE classified 73% of PT4 strains as a single type. FAFLP analysis was carried out with the primer pair Eco RI+0 and Mse I+C, by simultaneously sampling 170 to 190 loci throughout the PT4 genome. Twenty-three FAFLP profiles, with 1 to 61 amplified-fragment differences, were found among the 30 strains. The index of discriminatory power of FAFLP analysis was 0.98, compared to 0.47 for PFGE. FAFLP analysis assigned genotypes to each PT4 outbreak, as well as sporadic PT4 infections, a significant development for the epidemiology and control of this zoonotic enteric pathogen.