Novel potentiators of beta-lactam antibiotics. Isolation of SQ28,504 and SQ28,546 from Chromobacterium violaceum.

Two novel compounds, SQ28,504 and SQ28,546 are produced by Chromobacterium violaceum. These compounds enhance the antibacterial activity of beta-lactam antibiotics against Gram-negative organisms. Both SQ28,504 and SQ28,546 induce morphological changes in the presence of beta-lactam antibiotics. Only SQ28,546 has weak antimicrobial activity against several Gram-negative organisms.