TABLE 2.
Antibiotic susceptibilities of P. aeruginosa strains
| Strain (plasmid) | MIC (μg/ml)a of:
|
||||||||
|---|---|---|---|---|---|---|---|---|---|
| CIP | FEP | CHL | TIC | ATM | IPM | GEN | TOB | AMK | |
| PAO1 | 0.25 | 2 | 64 | 16 | 4 | 2 | 2 | 0.5 | 4 |
| FE60 | 0.12 | 2 | 64 | 16 | 4 | 2 | 0.25 | 0.25 | 1 |
| EryR | 2 | 8 | 128 | 2 | 1 | 0.5 | 1 | 0.25 | 2 |
| EryR(pNF225) | 0.25 | NDb | 32 | NDb | 4 | 2 | 2 | 1 | 8 |
| FK06 | 2 | 8 | 128 | 4 | 1 | 0.5 | NDc | 0.25 | 1 |
| FK06(pNF225) | 0.25 | ND | 64 | ND | 4 | 2 | ND | 0.25 | 1 |
| 3308 | 2 | 4 | 128 | 2 | 1 | 0.12 | 0.25 | 0.12 | 0.5 |
| 3308(pNF225) | 0.12 | ND | 64 | ND | 4 | 2 | 1 | 0.25 | 1 |
| 2439 | 2 | 8 | 128 | 4 | 1 | 0.5 | 0.5 | 0.25 | 1 |
| 2439(pNF225) | 0.25 | ND | 64 | ND | 4 | 2 | 2 | 0.5 | 2 |
| 2126 | 2 | 8 | 128 | 4 | 1 | 0.5 | 0.5 | 0.25 | 1 |
| 2126(pNF225) | 0.25 | ND | 32 | ND | 4 | 1 | 2 | 0.5 | 2 |
| 1956 | 1 | 2 | 128 | 8 | 1 | 2 | 1 | 0.25 | 1 |
| 1956(pNF225) | 0.25 | ND | 64 | ND | 4 | 4 | 2 | 0.5 | 2 |
Modal values of three independent determinations. Underlined MICs are at least fourfold lower than those for wild-type strain PAO1; MICs in boldface are at least fourfold higher than those for wild-type strain PAO1. Abbreviations: CIP, ciprofloxacin; FEP, cefepime; CHL, chloramphenicol; TIC, ticarcillin; ATM, aztreonam; IPM, imipenem; GEN, gentamicin; TOB, tobramycin; AMK, amikacin. ND, not determined.
Susceptibility to FEP and TIC could not be measured accurately in strains complemented with recombinant nfxB plasmid pNF225 because of the hydrolytic activity of plasmid-encoded β-lactamase toward these two molecules. Control experiments with parent vector pMT45 showed that addition of 150 μg/ml ticarcillin to growth cultures for pNF225 maintenance did not influence the MICs of other antibiotics.
This strain contains a chromosomal cassette conferring high-level resistance to gentamicin.