Objective: Solid organ transplant recipients (SOTR) have been significantly impacted by the emergence of multidrug-resistant bacteria, including extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (EB). We determined the risk factors for and outcomes with ESBL-EB bloodstream infection (BSI) among SOTR.

Methods: A case-control and retrospective cohort study were conducted at the Hospital of the University of Pennsylvania from Jan 1, 2007 to July 1, 2016. All SOTR presenting with an EB BSI were included. Case/exposed patients were those with a likely ESBL-EB BSI (defined by a ceftriaxone minimum inhibitory concentration [MIC] ≥8[micro]g/mL). Control/unexposed subjects were those with a non-ESBL EB BSI. The primary outcome in the time-to-event analysis was graft failure or death within 60 days of the index blood culture. Multivariable logistic and Cox proportional hazard regression analyses were performed.

Results: Of 287 total SOTR with an EB BSI, 51 (17.8%) were likely ESBL-EB. Significant independent risk factors for ESBL-EB BSI included: carbapenem exposure in the prior 6 months (adjusted odds ratio [aOR] 3.13, 95% confidence interval [CI] 1.12-8.75, P 0.03); isolation of ESBL-EB on clinical culture in the prior 1 year (aOR 13.5, 95% CI 4.75-38.5, P <0.01); increased age (aOR 1.04, 95% CI 1.00-1.08, P 0.04); and linezolid exposure in the prior 6 months (aOR 3.70, 95% CI 1.40-9.99, P 0.01). In the outcomes analysis, there was a significantly higher hazard of graft failure or death associated with ESBL-EB BSI compared to non-ESBL EB BSI (adjusted hazard ratio [aHR] 2.46, 95% CI 1.03-5.89, P 0.04), after adjusting for baseline factors, such as recent rejection, and severity of infection.

Conclusions: There were high rates of ESBL-EB BSI among this cohort of SOTR. Similar to prior studies, the modifiable risk factors for ESBL-EB BSI included recent exposure to broad-spectrum antibiotics. Further, we found relatively poor outcomes among SOTR with an ESBL-EB BSI, with high rates of graft failure and death within 60 days. These findings underscore the importance of antibiotic stewardship among SOTR.

CITATION INFORMATION: Anesi J., Blumberg E., Lautenbach E., Tamma P., Thom K., Alby K., Bilker W., Omorogbe J., Tolomeo P., Werzen A., Nemati K., Han J. Risk Factors and Outcomes with Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae Bloodstream Infections among Solid Organ Transplant Recipients Am J Transplant. 2017;17 (suppl 3).

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