Use of an Efflux-Deficient Streptococcus pneumoniae Strain Panel To Identify ABC-Class Multidrug Transporters Involved in Intrinsic Resistance to Antimicrobial Agents

Thirteen derivatives of the Streptococcus pneumoniae TIGR4 strain in which putative drug efflux pumps were genetically inactivated were constructed and characterized. The results indicate that two linked genes encoding the ABC-type transporters SP2073 and SP2075 function together to confer intrinsic resistance to a series of structurally unrelated compounds, including certain fluoroquinolones.