Outcome Based Study of Carbapenem Use Relative to ESBLs (OBSCURE)

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The prevalence of bloodstream infections (BSIs) due to ESBL-producing organisms has increased dramatically over the past years. Based on available data, use of non-carbapenem antibiotics are usually discouraged in severe infections caused by these organisms, as clinical response cannot be reliably predicted based solely on antimicrobial susceptibility studies. Methods

We conducted a retrospective analysis in a three-hospital regional health system. We reviewed 57 patients admitted from October 1, 2010 to December 31, 2014 who had ESBL producing organisms identified in blood cultures processed in our central microbiology laboratory and collected data regarding selection of antibiotics and clinical outcomes. Results

Of 57 patients analyzed, 32 (56.1 %) were treated with carbapenem antibiotics (group 1) and 25 (43.9%) with non-carbapenem antibiotics (group 2), the most common alternative antibiotic being piperacillin-tazobactam (44%). The most common sources of the bacteremia were urine and biliary (33.3% and 19.3% respectively). We also noted that patients treated with carbapenem antibiotics had markedly higher cure rates with the first used antimicrobial (78% vs. 28%; P = 0.0001) as 44% of patients on group 2 required transition to a carbapenem antibiotic due to lack of clinical improvement and 28% either died or were transitioned to hospice on the same admission. Thirty-day readmission rates were lower in group 1 (10.7% vs. 42.1%; P = 0.013) as was length of hospital stay (17.4 days vs. 20.7 days, P = 0.33). Conclusion

Infections caused by ESBL producing organisms are still relatively uncommon, however its prevalence continues to rise at alarming rates. Better understanding of its clinical response to different antimicrobials is of utmost importance. Our study outlines that better clinical response to carbapenems that also reflected in improved mortality, shorter hospital stays and lower rates of readmission.


ID Week, San Diego, CA, October 4, 2017.