Table 1.

Amount of AmpC β-lactamase determined by quantitative PCR in cultures of Pseudomonas aeruginosa PAO1 AmpC-overexpressed isogenic mutant in presence of cefepime alone or in combination with tobramycin at hour 5 of drug exposure

Regimen	Fold increase in AmpC RNA expression (95% confidence interval)
Growth control	22.0 (5.1–95.0)
Cefepime, 2,000 mg	259.0 (125.0–5,540.0)
Tobramycin, 7 mg/kg	0.7 (0.3–1.7)
Cefepime + tobramycin	13.9 (7.5–25.5)