Structure of P. aeruginosa LpxC with compound 18d: (2R)-N-Hydroxy-4-(6-((1-(hydroxymethyl)cyclopropyl)buta-1,3-diyn-1-yl)-3-oxo-1H-pyrrolo[1,2-c]imidazol-2(3H)-yl)-2-methyl-2-(methylsulfonyl)butanamide