Clinical Research Directory

Inclusion Criteria: 1. Provide written informed consent prior to any study-related procedures not part of normal medical care. Surrogate consent/use of a legally authorized representative may be provided if permitted by local country and institution-specific guidelines 2. Male subjects or female subjects ≥ 18 and ≤ 82 years of age at the time of signing informed consent. 3. A known or highly suspected infection caused by CRABC (VABP, HABP, or BSI of non-urinary tract origin) as either a single pathogen or member of a polymicrobial infection 4. Diagnosed with HABP, VABP or BSI 5. Acute Physiology and Chronic Health Evaluation (APACHE II) score ≤ 30, within 24 hours prior to randomization. Part B specific inclusion criteria 6. Confirmed CRABC ventriculitis or meningitis based on evidence from CSF culture collected within 72 hours prior to enrollment (as per standard of care). 7. Functioning EVD that can be used for safe and timely CSF sampling. 8. No contraindications to CSF sampling via EVD in the volumes required by the protocol Main Exclusion Criteria: 1\. Urinary tract infection as source of A. baumannii BSI2. Known or suspected community acquired bacterial pneumonia or viral (including SARS-CoV-2), pneumonia within the last 7 days 3. Known or suspected viral pneumonia within the last 7 days before screening e.g. positive for SARS-CoV-2 or influenza. 4\. Known fungal or parasitic pneumonia. 5. Patients classified under futility of care, as determined by the medical team, indicating a lack of potential for benefit from intervention or patients who are permanent residents of long-term care facilities and have been assessed as receiving palliative or comfort-focused care. 6\. Sustained shock with persisting hypotension requiring vasopressors to maintain mean arterial pressure ≥ 65 mmHg (calculate mean arterial pressure = diastolic pressure plus 1/3 (systolic pressure minus diastolic pressure)) with patients requiring escalating vasopressor support to maintain adequate arterial pressure in conjunction with rising lactate.7. Known or suspected allergies to polymyxins, rifabutin, ceftazidime/avibactam, cefiderocol, or their excipients. 8\. Inability to insert a central catheter or a peripherally inserted central catheter (PICC).11. Acute graft versus host disease Grade ≥ 3. 12\. Expected survival \< 72 hours or a Do Not Resuscitate Order. 13. Burns \> 40% of total body surface area. 14. Presence of neutropenia (absolute neutrophil count \< 1500/mm3) obtained from a local laboratory at Screening, or anticipated neutropenia with absolute neutrophil count \< 1500 cells/mm3. 15\. Severe renal disease defined as an estimated glomerular filtration rate (eGFR) as per Modification of Diet in Renal Disease (MDRD) formula (MDRD eGFR) \< 30 mL/min/1.73 m2, or requirement for peritoneal dialysis, hemodialysis, hemofiltration, or a urine output \< 20 mL/hour over a 24 hour period.