Emerging broad-spectrum resistance in Pseudomonas aeruginosa and Acinetobacter baumannii: Mechanisms and epidemiology

Int J Antimicrob Agents. 2015 Jun;45(6):568-85. doi: 10.1016/j.ijantimicag.2015.03.001. Epub 2015 Mar 24.


Multidrug resistance is quite common among non-fermenting Gram-negative rods, in particular among clinically relevant species including Pseudomonas aeruginosa and Acinetobacter baumannii. These bacterial species, which are mainly nosocomial pathogens, possess a diversity of resistance mechanisms that may lead to multidrug or even pandrug resistance. Extended-spectrum β-lactamases (ESBLs) conferring resistance to broad-spectrum cephalosporins, carbapenemases conferring resistance to carbapenems, and 16S rRNA methylases conferring resistance to all clinically relevant aminoglycosides are the most important causes of concern. Concomitant resistance to fluoroquinolones, polymyxins (colistin) and tigecycline may lead to pandrug resistance. The most important mechanisms of resistance in P. aeruginosa and A. baumannii and their most recent dissemination worldwide are detailed here.

Keywords: Acinetobacter baumannii; Aminoglycosides; Carbapenems; Multidrug resistance; Pseudomonas aeruginosa; β-Lactams.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Acinetobacter Infections / epidemiology*
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / isolation & purification
  • Aminoglycosides / pharmacology
  • Anti-Bacterial Agents / pharmacology*
  • Cross Infection / epidemiology
  • Cross Infection / microbiology
  • Drug Resistance, Multiple, Bacterial*
  • Humans
  • Pseudomonas Infections / epidemiology*
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / isolation & purification
  • beta-Lactams / pharmacology


  • Aminoglycosides
  • Anti-Bacterial Agents
  • beta-Lactams