Poly-beta-peptides from functionalized beta-lactam monomers and antibacterial compositions containing same

An antibiotic composition comprising, in combination:

• an antibiotic-effective amount of at least one β-polypeptide comprising internal subunits having a structure selected from the group consisting of:
• wherein R3, R4, R5, and R6 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted C1-C6-alkyl, aryl, C1-C6-alklyaryl, amino, protected-amino, amino-C1-C6-alkyl, and protected-amino-C1-C6-alkyl;
• and
• wherein A together with the carbon atoms to which it is attached is selected from the group consisting of substituted or unsubstituted C5-C12 cycloalkyl, C5-C12 cycloalkenyl, and five- to twelve-membered heterocyclic;
• and
• a pharmaceutically-suitable carrier.