Abstract: The pharmacodynamic effect of amoxycillin against Staphylococcus aureus was evaluated in an in-vitro pharmacodynamic model. For amoxycillin peak concentrations of 0.4, 1.0, 1.6 and 3.2 mg mL–1 and half-lives of 2 and 5.5 h were examined. The bactericidal effect was measured as the reduction in colony count (log CFU mL–1) during the experimental period and the overall pharmacodynamic effect as the area under the bacterial growth versus time curve (AUBC). In an in vitro model with elimination half-life of 2 h, only 16 MIC amoxicillin exhibited persistent killing of Staphylococcus aureu with a bacterial number reduction of 2.51 lo–10. in an in vitro model with simulative elimination half-life of 5.5 h, 5, 8 and 16 MIC amoxicillin exhibited persistent killing of Staphylococcus aureu with a bacterial number reduction of 2.42, 2.72 and 2.53 lo–10 noted during the 12 h, respectively. These data indicate that amoxicillin reach the maximum killing at 5-folds of their MIC values and the antimicrobial maintaining time is mainly correlated with T>MIC. But during the whole experimental period, bactericidal effect and bacterial elimination were not achieved on Staphylococcus aureu strains for which the MIC was 0.2 μg mL–1, even with a Cmax/MIC ratio of 16.
H.Z. Ding, D. Yang, Y.H. Yang and Z.L. Zeng, 2016. The Pharmacodynamic Effects of Amoxicillin Against Staphylococcus aureus in an In-vitro Kinetic Model. Journal of Animal and Veterinary Advances, 15: 69-74.