Genomic fingerprinting of shigatoxin-producing Escherichia coli (STEC) strains: comparison of pulsed-field gel electrophoresis (PFGE) and fluorescentamplified-fragment-length polymorphism (FAFLP)

For epidemiological studies of shigatoxin-producing Escherichia coli (STEC) infections, rapid, reproducible and highly discriminative methods are requ ired. In this study, we examined the performance of the fluorescent amplifi ed-fragment-length polymorphism (FAFLP) technique for epidemiological finge rprinting of STEC isolates and compared it to the acknowledged fingerprinti ng method pulsed-field gel electrophoresis (PFGE). A total of 88 STEC isola tes, including 82 of serotype O157:H7 or O157:H-, were subjected to fingerp rinting by both PFGE and FAFLP. The isolates included sporadic and epidemio logically related strains of both animal and human origin from widespread g eographical locations. The FAFLP fingerprint patterns confirmed the clonal nature of STEC O157 strains. Among the 82 O157:H7/H- isolates belonging to 49 distinct groups of epidemiological unrelated isolates, 24 FAFLP profiles and 51 PFGE patterns were obtained. Thus, PFGE had a higher discriminatory power than FAFLP and overall correlated better to available epidemiologica l data. Consequently, the PFGE technique remains the method of choice in ep idemiological investigations of STEC infections.