TABLE 3.

Evaluation of ampD gene homologs from P. aeruginosa using the E. coli AmpD plasmid model system

StrainaampC statusbAmpD1 form or mutation(s)cDiam (mm) of CAZ zone (susceptibility phenotype)dAmpDh2 form or mutation(s)cDiam (mm) of CAZ zone (susceptibility phenotype)dAmpDh3 form or mutation(s)cDiam (mm) of CAZ zone (susceptibility phenotype)d
PAO1eWTWT17 (I)WT6 (R)WT18 (S)
PA22PDGly148Ala, Asp183Tyr8 (R)WTNTfAsp137Gly, Ala219Thr10 (R)
PA367PDGly148Ala, Asp183Tyr8 (R)WTNTAsp137Gly, Ala219Thr10 (R)
PA24PD12-nt deletion at nt 5064908; deletion of codons 144-1476 (R)WTNTAla219Thr9 (R)
PA113PDGly148Ala, Asp183Tyr8 (R)WTNTAla219Thr9 (R)
GB57FDVal10Ile10 (R)WTNTWTNT
GB61PDGly148Ala12 (R)WTNTWTNT
TX291PD11-nt deletion at nt 5064907; frameshift11 (R)WTNTAla208Val8 (R)
TX292FD11-nt deletion at nt 5064907; frameshift11 (R)WTNTWTNT
164CDFDLeu32Pro, Gly46Ser, Gly148Ala8 (R)WTNTIle67Thr10 (R)
  • a P. aeruginosa strain from which ampD genes were amplified for analysis in the E. coli AmpD model system (18).

  • b ampC status based on ampC expression data presented in Table 2. Abbreviations are as defined in Table 2 footnote e.

  • c Nucleotides (nt) specifically mentioned in the table correspond to the PAO1 genome sequence (GenBank accession number NC_002516). WT, wild type.

  • d Ceftazidime (CAZ) disk diffusion data for cloned P. aeruginosa ampD genes within the E. coli AmpD model system (18). Failure to complement the ampD-deficient strain JRG582 was evaluated by the zone size for CAZ. CLSI Enterobacteriaceae breakpoints for CAZ were as follows: ≤14 mm, resistant (R); 15 to 17 mm, intermediate (I); and ≥18 mm, susceptible (S) (4).

  • e The ampD genes of PAO1 were tested in the model system as controls.

  • f NT, not tested because of the presence of the wild-type sequence.