Microbial contamination of autologous peripheral blood stem cell products: incidence, clinical outcome, quality control and management strategies.

BACKGROUND: Microbial screening is part of quality control for autologous peripheral blood stem cell (PBSC) manipulation. The incidence of culture positive products varies widely. The clinical significance of infusing culture positive products is uncertain, with no consensus on the interventions required. METHODS: Microbial cultures of 606 consecutive autologous PBSC products from 278 patients between 1995 and 2005 were retrospectively analysed to determine the incidence of culture positivity and classified according to likely clinical significance. Clinical outcomes of patients who received culture positive products were reviewed. Using the baseline probability of contamination, a quality control method to detect a systematic source of contamination during product manipulation was developed. RESULTS: Eleven (1.8%) of 606 products were culture positive in eight (2.9%) patients. Ten products yielded coagulase negative Staphylococcus species and one Corynebacterium accolens. One patient had catheter sepsis during collection. Five patients received culture positive products, with prophylactic antibiotics when there was known coagulase negative Staphylococcus species. None had clinical evidence of infection following product infusion. CONCLUSIONS: The incidence of culture positive products was comparable to published series. Only skin commensals were isolated. Infusion of skin commensal positive products appears safe with antibiotic prophylaxis. Using local and published experience, clinical and laboratory policies were developed for culture positive products.