Amoxicillin is an analog of ampicillin, derived from the basic penicillin nucleus, 6-aminopenicillanic acid Clavulanic acid is produced by the fermentation of Streptomyces clavuligerus. It is a beta-lactam structurally related to the penicillins and possesses the ability to inactivate some beta-lactamases by blocking the active sites of these enzymes. Lower Respiratory Tract Infections - caused by beta-lactamase-producing isolates of Haemophilus influenzae and Moraxella catarrhalis. Acute Bacterial Otitis Media - caused by beta-lactamase-producing isolates of H. influenzae and M. catarrhalis. Sinusitis - caused by beta-lactamase-producing isolates of H. influenzae and M. catarrhalis. Skin and Skin Structure Infections - caused by beta-lactamase-producing isolates of Staphylococcus aureus, Escherichia coli, and Klebsiella species. Urinary Tract Infections - caused by beta-lactamase-producing isolates of E. coli, Klebsiella species, and Enterobacter species.