Skip to main content

Table 4 Main mechanisms of acquired antimicrobial resistance in Pseudomonas aeruginosa

From: Mechanisms of antimicrobial resistance in Gram-negative bacilli

Mechanism Genetic event Antimicrobials
High-level expressed AmpC cephalosporinase Chromosomal mutation Penicillins (with or without beta-lactamase inhibitors), cephalosporins, aztreonam
Other beta-lactamases
 Penicillinasesa MGE acquisition Penicillins
 Extended-spectrum beta-lactamasesb   Penicillins, cephalosporins, aztreonam
 Metallo-beta-lactamasesc (carbapenemases)   Penicillins, cephalosporins, carbapenems
Loss of OprD (impermeability) Chromosomal mutation Imipenem
Active efflux pumps
 MexAB-OprM Chromosomal mutation Ticarcillin, cephalosporins, aztreonam, meropenem, fluoroquinolones
 MexXY-OprM   Cefepime (±penicillins), aminoglycosides, fluoroquinolones
 MexEF-OprN   Meropenem, fluoroquinolones
 MexCD-OprJ   Cefepime, aztreonam (+/− penicillins), fluoroquinolones
Aminoglycoside-modifying enzymesd MGE acquisition Aminoglycosides
16S rRNA methylases MGE acquisition Aminoglycosides
Topoisomerases modifications Chromosomal mutation Fluoroquinolones
Lipid A (LPS) modifications Chromosomal mutation Polymyxins
  1. MGE mobile genetic element (plasmid or transposon).
  2. Most common enzyme types: aPSE and OXA; bPER, SHV, GES and OXA; cVIM and IMP (SIM, GIM and SPM types are less common); dAAC(3)-I, AAC(3)-II, AAC(6′)-I, AAC(6′)-II and ANT(2′)-I.