The antibacterial activity of amoxycillin/clavulanic acid against Staphylococcus aureus ingested by human granulocytes.

The effect of amoxycillin, and amoxycillin/clavulanic acid on the in vitro interaction between human polymorphonuclear cells and a beta-lactamase producing strain of Staphylococcus aureus was investigated. Amoxycillin alone, at half the MIC, significantly inhibited the bacterial uptake by polymorphonuclear (PMN) cells compared with the control; as a consequence the killing of intracellular staphylococci was higher. Clavulanic acid did not have any significant effect upon the activities of phagocytes. The combination amoxycillin/clavulanic acid possesses beneficial properties which result in enhancement of both phagocytosis and microbicidal activity of PMN cells against the beta-lactamase producing strain of S. aureus. A synergic effect between drugs and serum activity was noted.