Pseudomonas aeruginosa

MICROBIOLOGY

• 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]