Scope: This position paper is intended for clinicians and data managers involved in the diagnosis, management, and reporting of bloodstream infection (BSI) and central venous catheter (CVC)-related BSI and CVC-related local skin/soft-tissue infections (lSSTI) in haematopoietic cell transplant (HCT) recipients.

Methods: The panel reviewed the relevant guidelines on BSI and CVC-related lSSTI definitions, and their applicability to HCT recipients. We developed practical recommendations aiming to establish their standardized reporting considering the unique features of HCT recipients. QUESTIONS ADDRESSED BY THE POSITION PAPER: .

Primary bsi definitions: Adequate blood volume is crucial for correct sampling. Definite BSI is defined as non-commensal pathogen identified by one positive culture or non-culture-based test, or two separate positive blood cultures with commensal pathogen, accompanied by any clinical or inflammatory markers deterioration. One positive blood culture set with viridans group Streptococci accompanied by clinical or inflammatory markers deterioration is defined as a probable BSI. After the validity confirmation, each primary BSI should be assessed for being a catheter-related BSI and/or mucosal barrier injury BSI; this terminology is not exclusive. CVC is considered a definite BSI source when the same pathogen grows from the cultures obtained from the CVC tip/hub and peripheral blood; confirmed by the differential time to positivity test or quantitative criteria. Mucosal barrier injury is considered a source when an intestinal pathogen grows in a patient with an appropriate clinical context.

Cvc-related lssti definitions: CVC-related lSSTI (e.g. exit site, tunnel infection) should be defined as clinically or microbiologically documented (or both).

Definition of recurrence and attributable mortality: Relapse should be differentiated from reinfection when reporting recurrence. We propose reporting 30-day mortality after BSI. Attributable mortality is defined if death directly attributed to BSI by the treating physician assessment. Uniform definition and reporting of BSI types will improve the analysis of their rates, related outcomes, and efficacy of preventative and treatment measures.