Although inactivation of the formylation process is the most common mechanism of reduced susceptibility, it significantly slows bacterial growth (Guillon et al. 1992; Mazel et al. 1994) and could lead to a drastic reduction in virulence, as shown for Staphylococcus aureus in mouse models (Margolis et al. 2000), indicating that despite the development of resistance, PDF inhibitors may remain effective in treating bacterial infections due to the co-associated growth defect and reduced virulence. This evidence concerns the gene PDF and bacterial infectious disease.