Clinical Research Directory

Inclusion Criteria: * Hospitalized neonate or young infant ≤90 days postnatal age at screening * Weight ≥2 kg * Receiving systemic antibiotic therapy * Tolerating enteral medication(s) and/or enteral feeds * Group 1: Receiving oral linezolid as part of routine clinical care. * Group 2: Receiving systemic antibiotic therapy but not prescribed linezolid clinically and eligible to receive a single oral study dose. Exclusion Criteria: * Known hypersensitivity or allergy to linezolid * Renal dysfunction (defined by age-appropriate serum creatinine and/or urine output) * Hepatic dysfunction (AST or ALT ≥3x age-specific upper limit of normal or clinically significant hepatic failure) * Gastrointestinal disorders expected to significantly impair drug absorption (e.g., short bowel syndrome, severe malabsorption) * Severe anemia or other condition that precludes study-required blood sampling * Extracorporeal support or other devices expected to substantially alter drug pharmacokinetics (e.g., extracorporeal membrane oxygenation \[ECMO\]). * Therapeutic hypothermia * Ongoing clinical instability that, in the opinion of the treating team or principal investigator (PI), would make study participation unsafe (e.g., escalating vasoactive support or rapidly worsening organ dysfunction).