What is the clinical significance of infusing hematopoietic cell grafts contaminated with bacteria?

Area of Science:

• Hematology
• Microbiology
• Transplant Science

Background:

• Routine sterility cultures are performed on hematopoietic stem cell (HSC) products.
• Bacterial contamination of HSC grafts is infrequent, and its clinical impact is poorly understood.

Purpose of the Study:

• To investigate the clinical outcomes of patients receiving HSC grafts with positive sterility cultures.
• To assess the incidence and consequences of bacterial contamination in HSC products.

Main Methods:

• Retrospective review of sterility cultures from 1502 bone marrow and peripheral HSC grafts from 938 patients (1990-2005).
• Assessment of adverse events, including fever and septicemia, for 14 days post-infusion.
• Correlation analysis between contamination rates and graft manipulation or patient condition.

Main Results:

• 1.0% (15/1502) of HSC grafts showed bacterial contamination (11 Gram-positive cocci, 2 Gram-positive bacilli, 2 Gram-negative bacilli).
• No correlation found between contamination rates and graft manipulation or patient's underlying condition.
• Only one case of Staphylococcus epidermidis bacteremia possibly linked to a contaminated graft was observed; 13 recipients received contaminated grafts.

Conclusions:

• Infusion of HSC grafts contaminated with common skin bacteria rarely results in adverse clinical outcomes.
• Close patient monitoring may be sufficient, potentially avoiding unnecessary antibiotic use and associated adverse events.