Exposure to quinolones is associated with carbapenem resistance among colistin-susceptible Acinetobacter baumannii blood isolates

Int J Antimicrob Agents. 2007 Nov;30(5):409-14. doi: 10.1016/j.ijantimicag.2007.06.026. Epub 2007 Sep 11.


In this study, we explored risk factors associated with bacteraemia caused by colistin-susceptible/carbapenem-resistant (Co(S)/Ca(R)) Acinetobacter baumannii. A retrospective cohort study of hospitalised patients with A. baumannii bacteraemia was performed at a tertiary care hospital over a 44-month period. Thirty-nine patients with bacteraemia due to A. baumannii (35 Intensive Care Unit and 4 ward patients) were included in the analysis. Twenty-five patients (64%) had bacteraemia due to Co(S)/Ca(R)A. baumannii and 14 patients (36%) had bacteraemia due to colistin-susceptible/carbapenem-susceptible A. baumannii. Mortality was 56% (14/25) and 35.7% (5/14) for patients in the two groups, respectively (P=0.22). Bivariate analysis showed that prior exposure to fluoroquinolones (P=0.01) and antipseudomonal penicillins (P=0.004) as well as a higher number of antibiotics in use on the day of bacteraemia (P=0.02) were associated with isolation of a Co(S)/Ca(R) strain among patients with A. baumannii bacteraemia. Multivariate analysis using a backward logistic regression model showed that only exposure to fluoroquinolones was associated with development of Co(S)/Ca(R)A. baumannii bacteraemia (odds ratio=11.6; 95% confidence interval 2.4-55.9; P=0.02). The appearance of Co(S)/Ca(R)A. baumannii infections represents a major threat to critically ill hospitalised patients. Exposure to fluoroquinolones is an independent risk factor for development of Co(S)/Ca(R)A. baumannii bacteraemia.

MeSH terms

  • Acinetobacter Infections / epidemiology
  • Acinetobacter Infections / microbiology*
  • Acinetobacter Infections / mortality
  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / isolation & purification
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology
  • Bacteremia / epidemiology
  • Bacteremia / microbiology*
  • Bacteremia / mortality
  • Blood / microbiology
  • Carbapenems / pharmacology*
  • Cohort Studies
  • Colistin / pharmacology*
  • Female
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Penicillins / therapeutic use
  • Quinolones / therapeutic use*
  • Retrospective Studies
  • Risk Factors
  • beta-Lactam Resistance*


  • Anti-Bacterial Agents
  • Carbapenems
  • Penicillins
  • Quinolones
  • Colistin