Phenotyping and genotyping methods applied to investigate the relatedness of Brazilian isolates of Enterobacter cloacae

In order to evaluate the resolving power of several typing methods to ident ify relatedness among Brazilian strains of Enterobacter cloacae, we selecte d twenty isolates from different patients on three wards of a University Ho spital (Orthopedics, Nephrology, and Hematology). Traditional phenotyping m ethods applied to isolates included biotyping, antibiotic sensitivity, phag e-typing, and O-serotyping. Plasmid profile analysis, ribotyping, and macro restriction analysis by pulsed-field gel electrophoresis (PFGE) were used a s genotyping methods. Sero- and phage-typing were not useful since the majo rity of isolates could not be subtyped by these methods. Biotyping, antibio gram and plasmid profile permitted us to classify the samples into differen t groups depending on the method used, and consequently were not reliable. Ribotyping and PFGE were significantly correlated with the clinical epidemi ological analysis. PFGE did not type strains containing nonspecific DNase. Ribotyping was the most discriminative method for typing Brazilian isolates of E. cloacae.