Novel Locus Required for Expression of High-Level Macrolide-Lincosamide-Streptogramin B Resistance in Staphylococcus aureus

The yycF1 (Ts) mutation in Staphylococcus aureus conferred hypersensitivity to macrolide-lincosamide-streptogramin B (MLS B ) antibiotics on strains either containing or lacking ermB . The overexpression of the S. aureus Ssa protein restored the yycF1 mutant to wild-type levels of susceptibility. Inactivation of ssa in an unmutagenized strain dramatically reduced ermB -based resistance. Conditional loss of function or expression of ssa in the yycF1 mutant is proposed to result in the observed hypersensitivity to MLS B antibiotics.