Epidemiology of Bloodstream Infections Caused by Escherichia coli and Klebsiella pneumoniae That Are Piperacillin-Tazobactam-Nonsusceptible but Ceftriaxone-Susceptible.
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ABSTRACT: Background:Piperacillin-tazobactam-nonsusceptible (TZP-NS) Enterobacteriaceae are typically also resistant to ceftriaxone. We recently encountered bacteremias due to Escherichia coli (Ec) and Klebsiella pneumoniae (Kp) that were TZP-NS but ceftriaxone-susceptible (CRO-S). Methods:We reviewed all Ec and Kp bacteremias from 2011 to 2015 at our center and assessed the prevalence, antimicrobial susceptibilities, genetic profiles, patient characteristics, treatments, and outcomes of TZP-NS/CRO-S infections. We identified risk factors for TZP-NS/CRO-S infections compared with Ec and Kp bacteremias that were TZP-S and CRO-S (Control Group 1) and compared outcomes of patients with TZP-NS/CRO-S bacteremias, Control Group 1, and patients bacteremic with extended-spectrum ?-lactamase (ESBL)-producing Ec and Kp. Results:There were 1857 Ec and Kp bacteremia episodes, of which 78 (4.2%) were TZP-NS/CRO-S (Ec: 50/1227 [4.1%]; Kp: 28/630 [4.4%]). All TZP-NS/CRO-S isolates were also ampicillin-sulbactam-NS. Of 32 TZP-NS/CRO-S isolates that were sequenced, 28 (88%) harbored bla TEM-1 or bla SHV-1, none had an ESBL or AmpC ?-lactamase gene, and many sequence types were represented. Independent risk factors for TZP-NS/CRO-S bacteremia were exposure to ?-lactam/?-lactamase inhibitors (BL/BLIs; adjusted odds ratio [aOR], 5.5; P < .001) and cephalosporins (aOR, 3.0; P = .04). Thirty-day mortality after TZP-NS/CRO-S bacteremia was 25%, which was similar to control groups and was similar in patients treated empirically with BL/BLIs compared with those treated with cephalosporins or carbapenems. Targeted therapy with cephalosporins did not yield a higher 30-day mortality rate than carbapenem therapy. Conclusions:TZP-NS/CRO-S Ec and Kp are emerging causes of bacteremia, and further research is needed to better understand the epidemiology, resistance mechanisms, and clinical impact of these strains.
SUBMITTER: Baker TM
PROVIDER: S-EPMC6290775 | biostudies-literature | 2018 Dec
REPOSITORIES: biostudies-literature
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