Porous materials that have absorbed sewage — carpet, underlay, plasterboard, chipboard flooring — generally cannot be salvaged and should be removed and disposed of properly.
Wear gloves, eye protection and a mask if you must enter the area, and wash thoroughly afterwards. Do not run a fan that blows air from the contaminated room into the rest of the house.
Photograph everything before clean-up. Many buildings policies cover escape of water and some cover sewage backup, and the evidence needs to be gathered before the room is stripped.