Is peptidoglycan a carbohydrate?

Yes, peptidoglycan is a carbohydrate. Its basic structure is comprised of a carbohydrate backbone made up of two alternating amino sugars - N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc). The alternating sugars are connected by a β-(1,4)-glycosidic bond.