First fatal central line-associated bloodstream infection caused by Alistipes onderdonkii

Alistipes onderdonkii (A. onderdonkii) is a rare anaerobic Gram-negative bacillus that forms part of the normal gastrointestinal microbiota but has recently emerged as an opportunistic pathogen in immunocompromised individuals. We report a fatal bacteremia due to A. onderdonkii in a 61-year-old man with end-stage renal disease on hemodialysis via a right internal jugular catheter and multiple comorbidities. He presented with septic shock; catheter cuff infection was evident. Anaerobic catheter blood cultures yielded a slow-growing Gram-negative bacillus identified as A. onderdonkii by MALDI-TOF MS. Susceptibility showed activity to amoxicillin-clavulanate, ampicillin-sulbactam, and metronidazole, with penicillin and ceftriaxone resistance. Therapy was de-escalated to ampicillin-sulbactam. Despite source control and ICU support, the patient developed gastrointestinal bleeding and multiorgan failure, culminating in death. This case highlights the pathogenic potential of A. onderdonkii as a cause of severe bloodstream infection in vulnerable patients with multiple comorbidities and chronic hemodialysis catheters. Increased awareness of this emerging Alistipes species may facilitate timely recognition, appropriate antimicrobial management, and further understanding of its clinical significance.