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Published on: May 28, 2014
Beta-lactams in continuous infusion for Gram-negative bacilli osteoarticular infections: an easy method for clinical
Alba Ribera1, Laura Soldevila1, Raul Rigo-Bonnin2
1Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.
Abstract:
Continuous infusion (CI) of beta-lactams could optimize their pharmacokinetic/pharmacodynamic indices, especially in difficult-to-treat infections.
Purpose:
To validate an easy-to-use method to guide beta-lactams dosage in CI (formula).
Methods:
A retrospective analysis was conducted of a prospectively collected cohort (n = 24 patients) with osteoarticular infections caused by Gram-negative bacilli (GNB) managed with beta-lactams in CI. Beta-lactams dose was calculated using a described formula (daily dose = 24 h × beta-lactam clearance × target "steady-state" concentration) to achieve concentrations above the MIC. We correlated the predicted concentration (Cpred = daily dose/24 h × beta-lactam clearance) with the patient's observed concentration (Cobs) measured by UPLC-MS/MS (Spearman's coefficient).
Results:
The most frequent microorganism treated was P. aeruginosa (21 cases; 9 MDR). Beta-lactams in CI were ceftazidime (n = 14), aztreonam (7), and piperacillin/tazobactam (3), mainly used in combination (12 with colistin, 5 with ciprofloxacin) and administered without notable side effects. The plasma Cobs was higher overall than Cpred; the Spearman correlation between both concentrations was rho = 0.6 (IC 95%: 0.2-0.8) for all beta-lactams, and rho = 0.8 (IC 95%: 0.4-1) for those treated with ceftazidime.
Conclusions:
The formula may be useful in clinical practice for planning the initial dosage of beta-lactams in CI, while we await a systematic therapeutic drug monitoring. The use of beta-lactams in CI was safe.
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