Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access
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Case Report

Volume 4, Number 12, December 2013, pages 820-824

Dissociation of Pharmacokinetic-Pharmacodynamic Success and Clinical Failure of Tazobactam/Piperacillin in Escherichia coli Bacteremia: A Case Report


Figure 1.
Figure 1. Clinical course. Right lower abdominal pain improved and pyuria turned negative after administering TAZ/PIPC, but fever and bacteremia still continued. After TAZ/PIPC was replaced with PZFX and TOB, fever subsided and blood culture was sterilized. Abdominal CT (bottom) shows gradual reduction in size and subsequent disappearance of the left renal abscess after antimicrobial switch to PZFX. TAZ/PIPC: Tazobactam/piperacillin 4.5 g × 3 div; TOB: Tobramycin 150 mg × 1 div; PZFX: Pazufloxacin 500 mg × 1-2 div; CPFX: Ciprofloxacin 400 mg/day p.o. MICs were determined by microdilution method.
Figure 2.
Figure 2. Pharmacokinetics-pharmacodynamics analysis. The serum peak/trough levels were 269/11 µg/mL for PIPC and 41/5 µg/mL for TAZ. The time during which the serum concentration of TAZ/PIPC exceeds the MICs of the E. coli strains ranged from 70% at the MIC of 16 µg/mL to 100% at the MIC of 2 µg/mL. Serum concentrations of piperacillin and tazobactam were quantitated by HPLC, and pharmacokinetic parameters were determined using Sawchuk-Zaske equation as described previously [5, 6].


Table 1. Pharmacokinetics of Piperacillin/Tazobactam
VD (L)CL (mL/min)Cmax (mg/mL)kel (h-1)T1/2 (h)
VD: volume of distribution; CL: total drug clearance; kel: elimination rate constant; T1/2: elimination half-time; NA: not available.
Present case13.8298.892690.431.61
Koomanachai et al [7]9.56 ± 6.59173.5 ± 75.33NA0.920.75
Kuti et al [8]11.9 ± 1.70181.67 ± 20.00NA1.090.64
Shiba [9]11.6 ± 2.1183 ± 413160.8210.844