Asparenomycins A, B and C, new carbapenem antibiotics. IV. Antibacterial activity

Asparenomycins (ASM) A, B and C, new members of the carbapenem family of antibiotics, are broad spectrum antibiotics with activity against Gram-positive and Gram-negative bacteria. ASM A was bactericidal to both aerobic and anaerobic bacteria, although morphological alterations of ASM A exposed cells differed significantly between Escherichia coli and Bacteroides fragilis; with the former ovoidal forms were produced while with the latter elongated forms were seen. Synergistic activities were observed with a combination of ASM A and ampicillin (ABPC) against various ABPC-resistant bacteria presumably as a result of the inhibition by ASM A of beta-lactamases. ASM A showed relatively weak therapeutic activity against E. coli infected mice, because of instability in body fluids, a common property of the carbapenem family of antibiotics.