A Study to Assess the Safety, Tolerability, and Pharmacokinetics of Single and Multiple Doses of Cefiderocol in Hospitalized Pediatric Participants

The primary objectives of this study are: * To assess the safety and tolerability of cefiderocol after single-dose administration in hospitalized paediatric participants 3 months to \< 18 years of age with suspected or confirmed aerobic Gram-negative bacterial infections * To assess the pharmacokinetics (PK) of cefiderocol after single-dose administration of cefiderocol in hospitalized paediatric participants 3 months to \< 18 years of age with suspected or confirmed aerobic Gram-negative bacterial infections * To assess the safety and tolerability of cefiderocol after multiple-dose administration in hospitalized paediatric participants 3 months to \< 12 years of age with suspected or confirmed aerobic Gram-negative bacterial infections * To assess the PK of cefiderocol after multiple-dose administration in hospitalized paediatric participants 3 months to \< 12 years of age with suspected or confirmed aerobic Gram-negative bacterial infections

This is a multicenter, single-arm, open-label, single- and multiple-dose study to assess the safety, tolerability, and PK of cefiderocol in hospitalized paediatric participants. The single-dose phase will include 4 separate cohorts of participants, grouped according to age range: * Cohort 1: 12 to \< 18 years * Cohort 2: 6 to \< 12 years * Cohort 3: 2 to \< 6 years * Cohort 4: 3 months to \< 2 years Cohorts 1, 2, and 3 in the single-dose phase will be initiated in parallel. Cohort 4 will begin after safety and PK data from at least 6 participants from the single-dose Cohorts 1, 2, and 3 (with a minimum of 3 participants from Cohort 3) have been assessed. The multiple-dose phase will include 3 cohorts according to age range (Cohorts 2, 3, and 4) and will begin after safety and PK data from 6 participants in the corresponding single-dose cohort have been assessed.