Table 6.
Resistance mechanisms in target organisms.
| Antibiotic | Target Organism | Resistance Mechanism |
|---|---|---|
| Aztronam/avibactam | Enterobacterales | Multiple β-lactamase production; mutations in PBP3 gene |
| P. aeruginosa | Efflux, impermeability, PDC variants; presence of OXA determinants (other than OXA-48) | |
| S. maltophilia | Efflux; β-lactamase overexpression | |
| Cefepime/enmetazobactam | Enterobactarales | NA |
| Cefepime/taniborbactam | Enterobacterales | NDM, VIM or IMP variants; impermeability |
| P. aeruginosa | VIM variants; impermeability; PDC variants | |
| S. maltophilia | NA | |
| Cefepime/zidebactam | Enterobacterales | Multiple β-lactamase production |
| P. aeruginosa | Efflux; mutations in PBP genes | |
| S. maltophilia | NA | |
| Cefiderocol | Enterobacterales | Mutations in genes involved in iron metabolism |
| P. aeruginosa | Mutations in genes involved in iron metabolism; PDC variants | |
| Acinetobacter | Mutations in genes involved in iron metabolism; mutations in PBP genes | |
| S. maltophilia | Mutation in genes involved in iron metabolism | |
| Ceftaroline/avibactam | Enterobacterales | NA |
| Ceftolozane/tazobatcam | Enterobacterales | Mutations in β-lactamase genes |
| P. aeruginosa | Presence of GES or PER determinants; efflux, impermeability, PDC variants; overexpression of PDC | |
| Ceftazidime/avibactam | Enterobacterales | Mutations in β-lactamase genes; efflux; β-lactamase overexpression; impermeability; multiple copies of β-lactamase genes |
| P. aeruginosa | Efflux, impermeability, PDC variants | |
| Imipenem/relebactam | Enterobacterales | Impermeability |
| P. aeruginosa | Efflux; impermeability | |
| Meropenem/nacubactam | Enterobacterales | NA |
| P. aeruginosa | NA | |
| Meropenem/vaborbactam | Enterobacterales | Efflux; impermeability; multiple copies of β-lactamase genes |
NA: not available; PDC: Pseudomonas-derived cephalosporinase.