Identification of Streptococci to Species Level by Sequencing the Gene Encoding the Manganese-Dependent Superoxide Dismutase

<jats:title>ABSTRACT</jats:title> <jats:p> We have used a PCR assay based on the use of degenerate primers in order to characterize an internal fragment ( <jats:italic> sodA <jats:sub>int</jats:sub> </jats:italic> ) representing approximately 85% of the genes encoding the manganese-dependent superoxide dismutase in various streptococcal type strains ( <jats:italic>S. acidominimus</jats:italic> , <jats:italic>S. agalactiae</jats:italic> , <jats:italic>S. alactolyticus</jats:italic> , <jats:italic>S. anginosus</jats:italic> , <jats:italic>S. bovis</jats:italic> , <jats:italic>S. constellatus</jats:italic> , <jats:italic>S. canis</jats:italic> , <jats:italic>S. cricetus</jats:italic> , <jats:italic>S. downei</jats:italic> , <jats:italic>S. dysgalactiae</jats:italic> , <jats:italic>S. equi</jats:italic> subsp. <jats:italic>equi</jats:italic> , <jats:italic>S. equi</jats:italic> subsp. <jats:italic>zooepidemicus</jats:italic> , <jats:italic>S. equinus</jats:italic> , <jats:italic>S. gordonii</jats:italic> , <jats:italic>S. iniae</jats:italic> , <jats:italic>S. intermedius</jats:italic> , <jats:italic>S. mitis</jats:italic> , <jats:italic>S. mutans</jats:italic> , <jats:italic>S. oralis</jats:italic> , <jats:italic>S. parasanguis</jats:italic> , <jats:italic>S. pneumoniae</jats:italic> , <jats:italic>S. porcinus</jats:italic> , <jats:italic>S. pyogenes</jats:italic> , <jats:italic>S. salivarius</jats:italic> , <jats:italic>S. sanguis</jats:italic> , <jats:italic>S. sobrinus</jats:italic> , <jats:italic>S. suis</jats:italic> , <jats:italic>S. thermophilus</jats:italic> , and <jats:italic>S. vestibularis</jats:italic> ). Phylogenetic analysis of these <jats:italic> sodA <jats:sub>int</jats:sub> </jats:italic> fragments yields an evolutionary tree having a topology similar to that of the tree constructed with the 16S rRNA sequences. We have shown that clinical isolates could be identified by determining the positions of their <jats:italic> sodA <jats:sub>int</jats:sub> </jats:italic> fragments on the phylogenetic tree of the <jats:italic> sodA <jats:sub>int</jats:sub> </jats:italic> fragments of the type species. We propose this method for the characterization of strains that cannot be assigned to a species on the basis of their conventional phenotypic reactions. </jats:p>