Truncated xpt gene present in invasive Streptococcus pneumoniae may have implications for MLST schemes

A serotype 1 disease-causing pneumococcus possessing a truncated xanthine phosphoribosyltransferase (xpt) housekeeping gene is described. The deletion is within the gene region used for multi-locus sequence typing (MLST) and may have occurred through genetic transformation or capsule switch between clones. The identification of this deletion in a clinical isolate therefore warrants highlighting due to potential errors that may ensue in isolate characterization and due to the fact that deletions may occur in other genes in this or other species characterized by MLST.