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Volume 3 Supplement 1


De-Escalating Anti-Pseudomonal β-Lactams


De-escalation of broad-spectrum antibiotics such as anti-pseudomonal beta-lactams is recommended to reduce antimicrobial selection pressure.


To identify factors associated with de-escalation of anti-pseudomonal beta-lactams in the Intensive Care Unit (ICU). To assess whether de-escalation was associated with outcome as measured by ICU mortality and acquisition of MDR-pathogens.


We retrospectively included all ICU episodes in Ghent University Hospital during 2013 and 2014 with prescription of meropenem, piperacillin-tazobactam or ceftazidime for at least 48 hours, stratifying between ICU episodes of < and ≥4 days; for outcome analysis, only the first ≥4 days episode per patient was included. De-escalation was defined as a change from meropenem to a non-carbapenem antibiotic other than colistin or aminoglycosides or a change from ceftazidime or piperacillin-tazobactam to a non anti-pseudomonal antibiotic. Organ failure improvement was defined as a decrease of the SOFA score between day 3 and day 1 of the infection for which the beta-lactam was prescribed. Antibiotics were considered appropriate if they covered all etiologic pathogens of the infection. Multidrug-resistant (MDR) pathogens were defined according to Magiorakos et al. (1). Acquisition of MDR pathogens was defined as the identification of MDR pathogens more than 2 days after the start of the antibiotic under study and not present before this date.


Anti-pseudomonal beta-lactam antibiotics (n = 609) were de-escalated in 23%: meropenem (n = 129) in 33% and piperacillin-tazobactam (n = 453) or ceftazidime (n = 27) in 20% (combined). De-escalation was not associated with the focus or severity of infection, but was significantly associated with organ failure improvement (p = 0.03) and with the identification of etiologic pathogens (p < 0.001). Total antibiotic duration in infections with and without de-escalation was 7 and 5 days, respectively (p < 0.001). in multivariable analysis examining the relationship between ICU-mortality and de-escalation with adjusment for organ failure improvement and focus and severity of infection, ICU mortality was not associated with de-escalation. Acquisition of MDR was not significantly different in episodes with or without de-escalation (33% versus 32%, p= 0.87).


De-escalation was associated with availability of etiologic microbiological cultures and improvement of the SOFA score. De-escalation was not associated with ICU mortality or with the acquisition of MDR pathogens.

Grant Acknowledgment

L. De Bus received a Clinical Research Grant from Ghent University Hospital, Belgium.


  1. Magiorakos AP, et al: Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance. Clin Microbiol Infect. 2012, 18: 268-281. 10.1111/j.1469-0691.2011.03570.x.

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Catteeuw, J., De Bus, L., Denys, W. et al. De-Escalating Anti-Pseudomonal β-Lactams. ICMx 3 (Suppl 1), A3 (2015).

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