CA-MRSA strains MW2 and LAC stimulated less TNF secretion by RAW264.7 murine macrophages in the presence of daptomycin than in the presence of vancomycin As previously observed with two USA300 CA-MRSA strains isolated from Memphis children with invasive staphylococcal infections [11] , macrophages exposed to either of the two prototypical CA-MRSA strains studied (the USA300 strain, LAC, or the USA400 strain, MW2) secreted significantly less TNF in the presence of daptomycin as compared with vancomycin (more than 50% reduction in each strain; Figure 1 ). Macrophage TNF secretion in response to MW2 was 34,535 ± 1,536 pg/ mL in the presence of vancomycin and 15,377 ± 1,267 pg/mL in the presence of daptomycin, a reduction of 55%, significant at p < 0.05. Similarly, macrophage TNF secretion in response to LAC in the presence of vancomycin was 33,345 ± 1,535 pg/mL, and 14,432 ± 1,536 pg/mL in the presence of daptomycin, a reduction of 57%, significant at p < 0.05. We previously reported similar findings in six S. aureus clinical isolates (including two pediatric CA-MRSA isolates of the USA300 group), suggesting that this effect of daptomycin is conserved in many different S. aureus isolates.