<qa>  What is the beta-lactam compound that exerts a time-dependent bacterCeftazidime is a beta-lactam compound that exerts a time-dependent bactericidal effect. Numerous arguments are in favor of continuous administration of ceftazidime, both for reasons of clinical efficacy and to preserve bacteriological mutation. The investigators report a prospective, single-center, parallel-group, randomized, controlled trial comparing two modes of administration of ceftazidime, namely, continuous administration loading dose of 20 mgkg of body weight followed by 60 mgkgday versus intermittent administration 20 mgkg over 30 min every 8 h in 34 patients with ventilator-associated pneumonia due to Gram-negative bacilli. The study was performed over 48 h with 13 and 18 assessments of serum ceftazidime in the continuous-infusion group group A and the intermittent-fusion group group B, respectively. Bronchoalveolar lavage BAL was performed at steady state in both groups at 44 h to determine ceftazidime levels in the epithelial lining fluid. The investigators chose a predefined threshold of 20 mgliter for serum concentrations of ceftazidime because of ecological conditions in our center. 