Bloodstream infection due to Acinetobacter spp: epidemiology, risk factors and impact of multi-drug resistance
D W Wareham1, D C Bean, P Khanna
1Division of Infection, Barts and The London NHS Trust, London, UK. d.w.wareham@qmul.ac.uk
Abstract:
Acinetobacter spp. are increasingly reported as important causes of human infection. Many isolates exhibit multi-drug resistance, raising concerns over our ability to treat serious infections with these organisms. The impact of infection on clinical outcome as well as the importance of multi-drug resistance is poorly defined. A descriptive retrospective observational study was undertaken of all episodes of Acinetobacter bacteremia occurring in a UK tertiary care centre from 1998-2006. Demographics of infected patients, characteristics and antimicrobial susceptibility of infecting strains were recorded and the impact of antimicrobial therapy on all causes of 30-day mortality assessed. Three hundred ninety-nine episodes of Acinetobacter bacteremia were identified, with A. baumannii being the most frequently isolated species. Most episodes occurred in critical care and were associated with multidrug resistance, with carbapenem resistance rising from 0% in 1998 to 55% in 2006. Although bacteremia due to carbapenem-resistant Acinetobacter and a requirement for critical care were associated with a higher mortality, mortality was not reduced by the administration of appropriate empirical antimicrobial therapy. A prospective study is required to identify both the most effective intervention and those most likely to benefit from treatment.
Insights
Acinetobacter infections are rising, with multi-drug resistance a growing concern. Appropriate empirical antimicrobial therapy did not reduce 30-day mortality in Acinetobacter bacteremia cases.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Acinetobacter species are significant causes of human infections.
- Increasing multi-drug resistance (MDR) in Acinetobacter complicates treatment.
- The clinical impact of MDR Acinetobacter infections requires further definition.
Purpose of the Study:
- To describe Acinetobacter bacteremia episodes in a UK tertiary care center.
- To assess the impact of antimicrobial resistance and therapy on patient outcomes.
- To evaluate mortality associated with Acinetobacter bacteremia from 1998-2006.
Main Methods:
- Retrospective observational study of 399 Acinetobacter bacteremia episodes.
- Analysis of patient demographics and infecting strain characteristics.
- Assessment of antimicrobial susceptibility and impact of therapy on 30-day mortality.
Main Results:
- Acinetobacter baumannii was the most common species identified.
- Most episodes occurred in critical care settings and were associated with MDR.
- Carbapenem resistance increased from 0% to 55% between 1998 and 2006.
- Higher mortality was linked to carbapenem-resistant Acinetobacter and critical care admission.
- Appropriate empirical antimicrobial therapy did not significantly reduce mortality.
Conclusions:
- Acinetobacter bacteremia, particularly with MDR strains, is associated with significant mortality.
- Current empirical antimicrobial strategies may not be sufficient to improve outcomes.
- Prospective studies are needed to identify effective interventions and patient subgroups.
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