TABLE 3.
In vitro potency of various beta-lactams against the isogenic strains of Pseudomonas aeruginosa containing various combinations of intrinsic resistance mechanisms relevant to beta-lactam antibiotics
| Straina | Genotype | Descriptionb | MIC (μg/ml) |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Meropenem | Aztreonam | Ceftolozane | Ceftazidime | Cefepime | Piperacillin | Levofloxacin | Amikacin | |||
| PAM1020 | Wild type | Wild type | 0.5 | 4 | 0.5 | 1 | 0.5 | 4 | 0.25 | 2 |
| PAM1101 | oprD1101 | OprD inactivated | 4 | 4 | 0.5 | 1 | 0.5 | 4 | 0.25 | 2 |
| PAM1032 | mexR::L75R | MexAB-OprM up | 2 | 32 | 1 | 4 | 4 | 16 | 2 | 2 |
| PAM1106 | mexA::Tet | MexAB-OprM inactivated | 0.125 | 0.125 | 0.5 | 0.5 | 0.25 | 0.125 | 0.06 | 2 |
| PAM1154 | oprM::Hg | MexAB-OprM and MexXY-OprM inactivated | 0.125 | 0.125 | 0.5 | 0.5 | 0.125 | 0.125 | 0.015 | 0.5 |
| PAM2156 | ampR::D135H | AmpC up | 2 | 64 | 4 | 32 | 8 | >128 | 0.25 | 2 |
| PAM2005 | mexR::L75R ampR::D135H | MexAB up, AmpC up | 4 | 64 | 4 | 32 | 8 | >128 | 2 | 2 |
| PAM2059 | mexR::L75R oprD2059 | MexAB up, OprD inactivated | 8 | 32 | 1 | 4 | 4 | 16 | 2 | 2 |
| PAM2091 | mexR::L75R ampR::D135H oprD2091 | MexAB up, AmpC up, OprD inactivated | 16 | 64 | 4 | 32 | 16 | >128 | 2 | 2 |
| PAM1033 | nfxB::T39I | MexCD-OprJ up | 0.25 | 1 | 0.5 | 0.5 | 4 | 2 | 4 | 0.25 |
| PAM1034 | mexT::P242R | MexEF-OprN up | 1 | 2 | 0.5 | 1 | 0.5 | 4 | 8 | 1 |
| PAM1323 | mexZ::Δ(aa25 to 39) | MexXY-OprM up | 0.5 | 4 | 0.5 | 1 | 2 | 4 | 0.5 | 4 |
a
All strains are derivatives of PAM1020 (PAO1). PAM1101 was selected from PAM1020 on 4 μg/ml of imipenem and carries a 198-bp deletion from −36 bp to +162 bp of oprD ATG; PAM2059 was selected from PAM1032 on 4 μg/ml of imipenem and carries TAA at amino acid (amino acid) number 399 of OprD; PAM2091 was selected from PAM2005 on 4 μg/ml of imipenem and has a frameshift from aa 407 of OprD. Selection or construction of efflux mutants is described in reference 37.
b
up, overexpressed.