title: Multidrug resistance, inappropriate empiric therapy, and hospital mortality in Acinetobacter baumannii pneumonia and sepsis.
abstract: The relationship between multidrug resistance (MDR), inappropriate empiric therapy (IET), and mortality among patients with Acinetobacter baumannii (AB) remains unclear. We examined it using a large U.S.
  
  
  
  We conducted a retrospective cohort study using the Premier Research database (2009-2013) of 175 U.S. hospitals. We included all adult patients admitted with pneumonia or sepsis as their principal diagnosis, or as a secondary diagnosis in the setting of respiratory failure, along with antibiotic administration within 2 days of admission. Only culture-confirmed infections were included. Resistance to at least three classes of antibiotics defined multidrug-resistant AB (MDR-AB). We used logistic regression to compute the adjusted relative risk ratio (RRR) of patients with MDR-AB receiving IET and IET's impact on mortality.
  
  
  
  Among 1423 patients with AB infection, 1171 (82.3 %) had MDR-AB. Those with MDR-AB were older (63.7 ± 15.4 vs. 61.0 ± 16.9 years, p = 0.014). Although chronic disease burden did not differ between groups, the MDR-AB group had higher illness severity than those in the non-MDR-AB group (intensive care unit 68.0 % vs. 59.5 %, p < 0.001; mechanical ventilation 56.2 % vs. 42.1 %, p < 0.001). Patients with MDR-AB were more likely to receive IET than those in the non-MDR-AB group (76.2 % MDR-AB vs. 13.8 % non-MDR-AB, p < 0.001). In a regression model, MDR-AB strongly predicted receipt of IET (adjusted RRR 5.5, 95 % CI 4.0-7.7, p < 0.001). IET exposure was associated with higher hospital mortality (adjusted RRR 1.8, 95 % CI 1.4-2.3, p < 0.001).
  
  
  
  In this large U.S. database, the prevalence of MDR-AB among patients with AB infection was > 80 %. Harboring MDR-AB increased the risk of receiving IET more than fivefold, and IET nearly doubled hospital mortality.
authors.affiliation: EviMed Research Group, LLC, PO Box 303, Goshen, MA, 01032, USA. evimedgroup@gmail.com.
authors.forename: Marya D
authors.initials: MD
authors.lastname: Zilberberg
authors.affiliation: OptiStatim, LLC, Longmeadow, MA, USA.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Nathanson
authors.affiliation: The Medicines Company, Parsippany, NJ, USA.
authors.forename: Kate
authors.initials: K
authors.lastname: Sulham
authors.affiliation: The Medicines Company, Parsippany, NJ, USA.
authors.forename: Weihong
authors.initials: W
authors.lastname: Fan
authors.affiliation: Washington Hospital Center, 110 Irving Street NW, Washington, DC, 20010, USA.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Shorr
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy*; D040981:Acinetobacter baumannii / Q000472:pathogenicity; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D015331:Cohort Studies; D018432:Drug Resistance, Multiple; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000188:drug therapy*; D018709:Statistics, Nonparametric
chemical_list: D000900:Anti-Bacterial Agents
keywords: Acinetobacter baumannii; Inappropriate empiric therapy; Multidrug resistance; Outcomes; Pneumonia; Sepsis