This is a safety and pharmacokinetic study of single-dose daptomycin in infants > 48 hours and < 120 days of age with suspected systemic infections. The investigators will enroll a total of 24 infants in 4 gestational age/postnatal age cohorts. Interim analyses will be performed after 3 infants are enrolled in each cohort. The investigators anticipate that 6 mg/kg of daptomycin will yield an AUC <740 mch*hr/mL.