6-Aminopenicillanic acid IV. Antibacterial activity

Abstract
6-Aminopenicillanic acid shows a similar order of activity against the Gram-positive cocci as against the Gram-negative bacilli. Compared with benzylpenicillin, the activity against the Gram-positive cocci is very low but against the Gram-negative bacilli, 6-aminopenicillanic acid shows a similar order of activity to benzylpenicillin. 6-Aminopenicillanic acid is bacteri­cidal at concentrations only slightly higher than the minimum inhibitory concentrations. Like benzylpenicillin, 6-aminopenicillanic acid appears to interfere with cell wall formation. Staphylococci trained to be resistant to 6-aminopenicillanic acid show resistance to benzyl­penicillin and vice versa.