In the Prove-it™ Sepsis assay, the identification of bacterial species is based on the gyrB (gyrase B or the subunit of topoisomerase II) and parE (the subunit of topoisomerase IV) topoisomerase genes. The topoisomerases are important enzymes needed in the DNA replication. In phylogenetic analysis, the gyrB gene has been more discriminative in bacterial identification than, for example, 16S rRNA gene (1). In the gyrB/parE genes, short DNA sequences presenting differences between various bacterial species, including closely related species, allow the use of these genes for species-level or taxon-level identification.

The broad-range PCR primers of the Prove-it™ Sepsis assay, which amplify both the parE and gyrB genes, are designed to target the highly conserved regions of these genes. Hybridization probes on the microarray are designed for the less conserved sequences flanked by the PCR primers. Each probe on the array has a match for a particular pathogen species or higher-level taxon, such as the genus. The technology has been described in more detail in proof-of-concept study (2).

1 Dauga, Int. J. Syst. Evol. Microbiol., 52: 531-547, 2002.
2 Roth et al., J. Clin. Microbiol., 42(9):4268-74, 2004.