(2S,3S,5R,6R)-3-[(2-{[N-(2,4-dihydroxy-3,3-dimethylbutanoyl)-beta-alanyl]amino}ethyl)sulfanyl]-6-(2-hydroxypropan-2-yl)-7-oxo-1-azabicyclo[3.2.0]heptane-2-carboxylic acid