SQ 26,180, a novel monobactam. I Taxonomy, fermentation and biological properties

Strains of Chromobacterium violaceum, isolated from various environments, were found to produce a novel monocyclic beta-lactam antibiotic. The antibiotic, SQ 26,180 was weakly active against Gram-positive and Gram-negative bacteria with the exception of mutants hypersensitive to beta-lactam antibiotics. The compound was highly stable to beta-lactamases and acted as an inhibitor of the P99 enzyme from Enterobacter cloacae. SQ 26,180 showed affinity for penicillin-binding proteins 1a, 4 and 5/6 of Escherichia coli and inhibited R61 DD-carboxypeptidases.