Stenotrophomonas maltophilia bloodstream infections in adult recipients of umbilical cord blood transplantation

Limited data are available on Stenotrophomonas maltophilia bloodstream infections (SM-BSIs) and the therapeutic efficacy of trimethoprim–sulfamethoxazole (SXT) against SM-BSI in umbilical cord blood transplant (uCBT) recipients. Medical and microbiological records of adult patients who received uCBTs between December 2008 and December 2015 at Toranomon Hospital (Tokyo, Japan) were reviewed. The efficacy and safety of SXT were evaluated only for recipients who were treated with ≥7 days of intravenous SXT for SM-BSI (evaluation cohort). Of 561 uCBT recipients, 34 developed SM-BSI. Diabetes mellitus (P = .005) and age ≥ 60 years (P = .013) were significant independent risk factors for SM-BSI. Moreover, SM-BSI was identified as an independent risk factor for all-cause mortality up to 100 days following uCBT (P = .025). Of the 34 recipients with SM-BSI, 24 were treated with an intravenous SXT-containing regimen (iSXT-CR). Septic shock (P = .0021), pneumonia (P = .011), neutropenia (P = .0015), and systemic steroid administration (P = .018) were identified as significant independent risk factors for 7-day crude mortality. The evaluation cohort included nine recipients. Doses of SXT were 2.4 to 6.9 mg/kg/day of the trimethoprim component. Of the nine recipients, five developed SM-BSI during the pre-engraftment phase. The 30-day crude-mortality rate and clinical cure rate of the cohort were 22% and 67%, respectively. Only one of the nine recipients experienced significant neutrophil toxicity. In this study, the epidemiology of SM-BSI in uCBT recipients was determined and its negative impact on survival was demonstrated. A low- to moderate-dose iSXT-CR appeared to be a tolerable and important therapeutic option for SM-BSI in the uCBT setting, including during the pre-engraftment phase.