In a previous study, we found that exposure of either of two CA-MRSA strains isolated from Memphis children (or any of four other S. aureus isolates from children with invasive staphylococcal infections) to daptomycin (compared with vancomycin) led to a less pronounced macrophage inflammatory response, characterized by diminished secretion of TNF and reduced accumulation of the inducible nitric oxide synthase (iNOS) [11] . In this study, we found that this differential effect of daptomycin (versus vancomycin) was also observed when macrophages were stimulated with either of the two prototypical CA-MRSA strains most widely studied today: the USA400 isolate, MW2, and the USA300 isolate, LAC. Importantly, ketamine pre-incubation inhibited macrophage TNF secretion in response to both CA-MRSA strains in the presence of daptomycin as well as in the presence of vancomycin, and the greatest suppression of TNF secretion was noted in the presence of both daptomycin and ketamine.