Ampicillin (D-(-)-alpha-Aminobenzylpenicillin) is a broad-spectrum beta-lactam antibiotic against a variety of gram-positive and gram-negative bacteria. It exhibits a good minimum inhibitory concentration for Staphylococcus aureus, Escherichia coli, Hemophilus influenzae, and Streptococcus pneumoniae with MICs of 0.6–1 mg/L, 4 mg/L, 0.25 mg/L, and 0.03-0.06 mg/L, respectively.