Impact of microbial contamination of haematopoietic stem cells on post‐transplant outcomes: A retrospective study from tertiary care centre in India

Abstract

Background Haematopoietic stem cells (HSC) may act as a source of infection for the recipient due to manipulation at multiple levels from collection to infusion. Due to the high risk of contamination cultures are usually taken during multiple steps. The clinical significance of microbial contamination of HSC on the post‐transplant course and the role of prophylactic antibiotics is relatively unknown. Aims and methods The aim of our study is to investigate the incidence of microbial contamination of haematopoietic stem cell and to assess its impact on the post‐transplant febrile neutropenia, engraftment kinetics, hospitalisation and day 100 mortality. Details of all patients admitted in the bone marrow transplantation unit of a tertiary care centre in India between January 2014 and December 2018 were collected from case records. Results Of the 1306 stem cell harvests from 503 patients sent for culture, 17 harvests (1.3%) were found to have a culture positive report. Sixteen patients had undergone autologous transplant. Multiple myeloma was most common indication of HSC transplant followed by Non‐Hodgkin Lymphoma (NHL). Twelve of 17 HSC cultures were positive at the time of infusion and five were positive at the time of harvest. The five HSC that were culture positive at the time of harvest were culture negative at the time of infusion. Gram‐positive organisms were isolated in six cultures and gram‐negative in rest. All patients developed febrile neutropenia post‐transplantation between day 1 and day 7. The median time of onset of fever was day +5 (1–7), the median duration of fever was 4 days (2–7), the median duration of antibiotic use was 11 days (9–16). Median day for neutrophil engraftment was 11 days (9–16), the median day for platelet engraftment was 14 days (10–25) and median duration of hospitalisation was 15 days (12–78). All patients were alive at day 100 of transplant. Conclusion This study shows that there appears to be minimal impact of culture positive HSC on transplant related outcomes in terms of engraftment kinetics, duration of hospitalisation and day 100 mortality. Discarding of contaminated HSC may not be required, though on development of febrile neutropenia appropriate antibiotics should be administered based on sensitivity pattern of HSC culture. Larger prospective studies are needed to determine the clinical relevance of such contaminations. Emphasis should be laid on better infection control practices to minimise contamination rates.

Successful autologous hematopoietic stem cell transplants using Salmonella positive products collected from asymptomatic donors

“…The decision to infuse both patients with the affected products was due to the limited availability of their autologous HSCs, and this decision was made only after heavy consideration of the potential risks and benefits and thorough discussion among the interdisciplinary clinical teams involved. Many instances of infusion of various HSC products contaminated with other organisms without subsequent significant adverse events have been reported, with or without the use of empiric antibiotics at the time of infusion 11,14,20–25 . However, there is potential for contaminated HSC products to cause sepsis and serious adverse events.…”