If you were located in the USA I would suggest Sigma Aldrich; however, I see you are based in France. Please update your location in the question. You can always extract LPS yourself from E. coli culture
Article Extraction, Purification and Characterization of Lipopolysac...
The outer membrane glycolipids of A. baumannii lack O-antigen which is an essential subunit of LPS. Therefore, A. baumannii is thought to produce lipooligosaccharide (LOS) instead of LPS. Take a look at the articles below;
Article Pathogenic Acinetobacter: from the Cell Surface to Infinity and Beyond
Article Acinetobacter baumannii : Envelope Determinants That Control...