Background: Antibiotic exposures have been described as risk factors for carbapenem-resistant Acinetobacter baumannii (CRAB) clinical infections. We aim to explore the impact of a three-day course of antibiotics on the occurrence of clinical infections with CRAB.
Methods: This retrospective cohort from 11/1/10 to 11/30/11 included consecutive patients admitted to the trauma intensive care unit (TICU), whom underwent rectal [and tracheal if intubated] surveillance cultures upon unit admission and weekly thereafter. Antibiotic exposure variables were constructed over 3-day windows. Within each exposure window, receipt of any carbapenem was entered as "1" and receipt of no carbapenems was entered as "0" in the model. The immediate hazards after each 3-day exposure windows were calculated. These variables were allowed to move over time within the model. APACHE on admission, age, time dependent surveillance cultures, and gender were also analyzed using Cox models and if significant were entered in the final multivariable model. Analyses were done using SAS [macros] 9.3 (Cary, NC).
Results: A total of 364 patients were analyzed. Sixty patients developed CRAB infections. Using 3-day exposure windows, carbapenems tripled the hazard ratio for the development of CRAB clinical infection (Figure 1). The maximum effect was seen on day 7 which then became non-significant after day 12.
Conclusion: A 3-day carbapenem exposure window increased the hazard of developing CRAB clinical infections, with a disappearance of the effect after day 12.
L. S. Munoz-Price,
S. Tarima, None
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