Risk factors for extended-spectrum beta-lactamase-producing Enterobacterales bloodstream infection among solid organ transplant recipients.

BACKGROUND: Approximately 40% of all Enterobacterales (EB) bloodstream infections (BSI) among solid organ transplant recipients (SOTR) are due to extended-spectrum beta-lactamase (ESBL)-producing organisms, but risk factors for such infections remain ill-defined in this population. Thus, we sought to determine the risk factors for ESBL-EB BSI among SOTR. METHODS: A multicenter case-control study was performed. All SOTR with an EB BSI at the Hospital of the University of Pennsylvania and University of Maryland Medical Center between January 1, 2007 and June 30, 2018, and at The Johns Hopkins Hospital between January 1, 2005 and December 31, 2015, were included. Cases were those with an ESBL-EB BSI. Controls were those with a non-ESBL-EB BSI. Multivariable logistic regression was performed to determine risk factors for ESBL-EB BSI. RESULTS: There were 988 episodes of EB BSI, of which 395 (40%) were due to an ESBL-EB. On multivariable analysis, the independent risk factors for ESBL-EB BSI included: ESBL-EB on prior culture (aOR 12.75, 95% CI 3.23-50.33, P<0.001); a corticosteroid-containing immunosuppression regimen (aOR 1.30, 95% CI 1.03-1.65, P=0.030); acute rejection treated with corticosteroids (aOR 1.18, 95% CI 1.16-1.19, P<0.001); and exposure to third-generation cephalosporins (aOR 1.95, 95% CI 1.48-2.57, P<0.001), echinocandins (aOR 1.61, 95% CI 1.08-2.40, P=0.020), and trimethoprim-sulfamethoxazole (aOR 1.35, 95% CI 1.10-1.64, P=0.003). CONCLUSIONS: We identified several novel risk factors that are uniquely important to the SOTR population, including exposure to trimethoprim-sulfamethoxazole and corticosteroid-containing immunosuppressive regimens. Further studies exploring these associations and testing interventions aimed at these modifiable risk factors among SOTR are needed.