Evaluating the Impact of Antibiotic Exposures as Time-Dependent Variables on the Acquisition of Carbapenem-Resistant Acinetobacter baumannii.
Crit Care Med 2017;
44:e949-56. [PMID:
27167999 DOI:
10.1097/ccm.0000000000001848]
[Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES
To determine the time-dependent effect of antibiotics on the initial acquisition of carbapenem-resistant Acinetobacter baumannii.
DESIGN
Retrospective cohort study.
SETTING
Forty-bed trauma ICU in Miami, FL.
PATIENTS
All consecutive patients admitted to the unit from November 1, 2010, to November 30, 2011.
INTERVENTIONS
None.
MEASUREMENTS AND MAIN RESULTS
Patients underwent surveillance cultures at admission to the unit and weekly thereafter. The primary outcome was the acquisition of carbapenem-resistant A. baumannii on surveillance cultures. Daily antibiotic exposures during the time of observation were used to construct time-dependent variables, including cumulative exposures (in grams and daily observed doses [defined daily doses]). Among 360 patients, 45 (12.5%) became colonized with carbapenem-resistant A. baumannii. Adjusted Cox models showed that each additional point in the Acute Physiologic and Chronic Health Evaluation score increased the hazard by 4.8% (hazard ratio, 1.048; 95% CI, 1.010-1.087; p = 0.0124) and time-dependent exposure to carbapenems quadrupled the hazard (hazard ratio, 4.087; 95% CI, 1.873-8.920; p = 0.0004) of acquiring carbapenem-resistant A. baumannii. Additionally, adjusted Cox models determined that every additional carbapenem defined daily dose increased the hazard of acquiring carbapenem-resistant A. baumannii by 5.1% (hazard ratio, 1.051; 95% CI, 1.007-1.093; p = 0.0243).
CONCLUSIONS
Carbapenem exposure quadrupled the hazards of acquiring A. baumannii even after controlling for severity of illness.
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