In S.pneumoniae strain 0100993 is found in the pezT/SP_1052/SP_1053 operon. Strains with a pezT/SP_1052/SP_1053 disruption have partially attenuated virulence, they take longer to develop a terminal infection in mice, although they grow normally in liquid culture. A double SP_1052/SP_1053 disruption grows almost as well as wild-type, showing the effect is mostly due to disruption of pezT.