aztreonam

2-[[[1-(2-Amino-4-thiazolyl)-2-[2-methyl-4-oxo-1-sulf-3-az etidinyl)amino]-2-oxoethylidene]amino]oxy]-2-methylpropan o ic acid; a synthetic bactericidal monolactam antibiotic with a wide spectrum of activity against Gram-negative aerobic pathogens.