ACC EPT

2 Some species of enterococci and streptococci are difficult to differentiate by phenotypic traits. The feasibility of using an oligonucleotide array for identification of 11 viridans group streptococci was previously established. The aim of this study was to expand the array to identify species of Abiotrophia (1 species), Enterococcus (18 5 species), Granulicatella (3 species), and Streptococcus (31 species and 6 subspecies). The method consisted of PCR amplification of the ribosomal DNA intergenic spacer (ITS) regions, followed by hybridization of the digoxigenin-labeled PCR products to a panel of oligonucleotide probes (16- to 30-mers) immobilized on nylon membrane. Probes were could be divided into three categories: species-specific, group-specific, 10 and supplemental probes. All probes were designed either from the ITS regions or from the 3 ’ end of the 16S rRNA genes. A collection of 312 target (162 reference strains and 150 clinical isolates) and 73 non-target strains was identified by the array