Enrollment will take place at 3-5 clinical sites in the United States. Full evaluation of inclusion and exclusion criteria will be conducted by each site's coordinator within 48 hours of initiation of daptomycin therapy. Subjects receiving daptomycin 6mg/kg (total body weight) once daily for a suspected/documented infection, as deemed necessary by the treating clinician will be screened for inclusion in the current study. Dialysate, ultrafiltrate, and blood flow rate utilized during the CVVHDF procedure will be determined by clinicians at discretion to optimize stability of patients.