Objective: To investigate the in vivo activities of ceftazidime and cefepime with susceptibility in vitro in rats with experimental pneumonia caused by extended-spectrum beta-lactamase-producing strain of Klebsiella pneumonia.
Methods: With intratracheal instillation method, 3 Klebsiella pneumonia strains isolated from this hospital were used to produce 3 groups of experimental model of pneumonia in rats. All the 3 strains showed resistant to cefotaxime and susceptible to piperacillin-tazobactam in vitro. To ceftazidime and cefepime, strain 1 was both susceptible. Strain 2 was susceptible to ceftazidime and resistant to cefepime. Strain 3 was resistant to ceftazidime and susceptible to cefepime. The three groups of rats were randomly assigned to one of the following five groups: one control group and four treatment groups. The efficacies were evaluated 96 hours later by the survival rate and the viable bacterial counts of the lungs (lg CFU/g).
Results: Group 1: piperacillin-tazobactam, ceftazidime and cefepime significantly improved the survival rate (75.0%, 76.9%, 80.0%) and reduced the bacterial counts [(10.8 +/- 2.8), (11.1 +/- 3.2), (11.0 +/- 3.7) lg CFU/g] compared with cefotaxime and the control group [36.0%, 32.0%; (15.7 +/- 5.6), (16.0 +/- 5.5) lg CFU/g; P < 0.05]. Group 2: piperacillin-tazobactam, ceftazidime significantly improved the survival rate (79.2%, 73.1%) and reduced the bacterial counts [(10.7 +/- 2.3), (11.0 +/- 2.7) lg CFU/g] compared with cefotaxime and the control groups [42.3%, 33.3%; (15.5 +/- 5.4), (15.8 +/- 4.6) lg CFU/g; P < 0.05]. Group 3: the survival rate in piperacillin-tazobactam and cefepime groups (80.8%, 75.0%) were significantly higher and the bacterial counts in piperacillin-tazobactam [(10.4 +/- 2.4) lg CFU/g] were significantly lower compared with the cefotaxime and the control groups [37.5%, 34.6%; (14.2 +/- 5.6), (15.3 +/- 4.9) lg CFU/g; P < 0.05].
Conclusion: Cefepime and ceftazidime can reduce the mortality and the number of viable bacteria in rat pneumonia caused by some ESBL-producing Klebsiella pneumonia strains susceptible to either of them and their efficacies were similar to piperacillin-tazobactam.