Listeria monocytogenes infections in hematopoietic cell transplant recipients: clinical manifestations and risk factors: A multinational retrospective case control study of the Infectious Diseases Working Party (IDWP) of the European Society for Blood and Marrow Transplantation (EBMT).

Background Listeriosis is rare after hematopoietic stem cell transplantation (HCT). Little is known about listeriosis in this population. Objectives To describe listeriosis following HCT and assess risk factors for listeriosis. Study design In this retrospective international case control study, we described 41 listeriosis episodes during 2000-2021 in HCT recipients (111 transplant centers; 30 countries) and assessed risk factors for listeriosis by comparing to matched controls. Results Forty-one listeriosis episodes (all due to Listeria monocytogenes, LM) in 30 allo- and 11 auto-HCT recipients occurred at a median of 6.2 (interquartile range [1Q-3Q] 1.6-19.3) months post-HCT. The estimated incidence was 49.8/100,000 in allo-HCT, and 13.7/100,000 population in auto-HCT. The most common manifestations were fever (39; 95%), headache (9; 22%), diarrhea, and impaired consciousness (8 each; 20%); 4 (10%) presented with septic shock; 19/38 (50%) were severely lymphocytopenic. Thirty-seven (90%) patients had LM bacteremia. Eleven (27%) patients had neurolisteriosis; 4/11 presented with non-specific signs, and 5/11 had normal brain imaging. Cerebrospinal fluid (CSF) analysis revealed high protein and, mainly neutrophilic, pleocytosis. Three-months mortality was 7/41 (17%): 3/11 (27%) among neurolisteriosis, and 4/30 (13%) among non-neurolisteriosis cases. In the multivariate analysis comparing to 74 controls, ≥2 HCT (OR [95%CI] 5.84 [1.10-30.82], p=0.038); and lymphocytopenia<500 cells/mm3 (OR [95%CI] 7.54 [1.50-37.83], p=0.014) were significantly associated with listeriosis. There were no statistically significant differences in background characteristics, immunosuppression, and cotrimoxazole prophylaxis between cases and controls. Conclusions HCT patients have an increased risk for listeriosis compared to general population. Listeriosis cause severe disease with septic shock and mortality. Neurolisteriosis can present with non-specific signs and normal imaging. Lymphocytopenia and non-first HCT are associated with increased risk of listeriosis; cotrimoxazole was not protective.