Unique Risks and Clinical Outcomes Associated With Extended-Spectrum β-Lactamase Enterobacteriaceae in Veterans With Spinal Cord Injury or Disorder: A Case-Case-Control Study

Abstract

OBJECTIVES To describe the burden of extended-spectrum β-lactamase (ESBL) Enterobacteriaceae in veterans with spinal cord injury or disorder (SCI/D), to identify risk factors for ESBL acquisition, and to assess impact on clinical outcomes DESIGN Retrospective case-case-control study PATIENTS AND SETTING Veterans with SCI/D and utilization at a Veterans' Affairs medical center from January 1, 2012, to December 31, 2013. METHODS Patients with a positive culture for ESBL Klebsiella pneumoniae, Escherichia coli, or Proteus mirabilis were matched with patients with non-ESBL organisms by organism, facility, and level of care and to uninfected controls by facility and level of care. Inpatients were also matched by time at risk. Univariate and multivariate matched models were assessed for differences in risk factors and outcomes. RESULTS A total of 492 cases (62.6% outpatients) were matched 1:1 with each comparison group. Recent prior use of fluoroquinolones and prior use of third- and fourth-generation cephalosporins were independently associated with ESBL compared to the non-ESBL group (adjusted odds ratio [aOR], 2.61; 95% confidence interval [CI], 1.77-3.84; P<.001 for fluoroquinolones and aOR, 3.86; 95% CI, 2.06-7.25; P<.001 for third- and fourth-generation cephalosporins) and the control group (aOR, 2.10; 95% CI, 1.29-3.43; P = .003 for fluoroquinolones; and aOR, 3.31; 95% CI, 1.56-7.06; P=.002 for third- and fourth-generation cephalosporins). Although there were no differences in mortality rate, the ESBL group had a longer post-culture length of stay (LOS) than the non-ESBL group (incidence rate ratio, 1.36; 95% CI, 1.13-1.63; P=.001). CONCLUSIONS All SCI/D patients with ESBL were more likely to have had recent exposure to fluoroquinolones or third- and fourth-generation cephalosporins, and hospitalized patients were more likely to have increased post-culture LOS. Programs targeted toward reduced antibiotic use in SCI/D patients may prevent subsequent ESBL acquisition. Infect Control Hosp Epidemiol 2016;37:768-776.