Evaluation of the effects of β-Lactamase on the Concentration of Ampicillin (ABPC) in the Bronchoalveolar Spaces by Bronchoalveolar Lavage in Rats

Abstract

The effects of β-lactamase on the concentration of Ampicillin (ABPC) in the bronchoalveolar spaces in rats was studied using a bronchoalveolar lavage (BAL) technique.
In the group with pneumonia due to non-β-lactamase-producing bacteria, the amount of ABPC recovered by BAL was greater than that in the normal group.
In the group with pneumonia due to β-lactamase-producing bacteria, the amount of ABPC recovered by BAL was less than that in the group with pneumonia due to non-β-lactamase-producing bacteria.
When K. oxytoca was used as the β-lactamase-producing bacteria and was present at a concentration of 10⁴ or more per ml in the BAL solution, the ABPC concentration found was below the limit of measurement.
Among the group with pneumonia due to K. oxytoca, the group with an intrapulmonary bacterial count of 6.1×10⁶/g had an amount of ABPC in lungs equal to approximately 10% of that in the group with a bacterial count of 5.0×10³/g.