Pseudomonas aeruginosa


  • Aerobic, motile, oxidase-positive, non-fermenting, Gram-negative bacillus.
  • Ubiquitous, isolated from soil, water, plants, and animals, especially at moist sites, such as perineum, axillae, and ears.
  • Thrives in moist environments of the hospital and in the community, i.e., respiratory equipment, disinfectants, sinks, hot-tubs, contact lens solution.
  • Drug resistance is common and multi-drug resistance (MDR) is increasingly common.
    • Mechanisms include permeability changes of the outer membrane, efflux pumps, chromosomal and inducible β-lactamases, and acquired genes and plasmid-mediated ESBLs.
  • Carbapenem-resistance mechanisms include:
    • Loss of outer membrane porin D (OprD)
    • The combined loss of OprD in combination with another mechanism, i.e., overexpression of AmpC β-lactamase OR overexpression of efflux pumps[10]
    • Production of carbapenemases, esp. Ambler class B metallo-beta-lactamases (NDM, VIM, IMP)[6]

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Last updated: August 29, 2021