What Causes Inability To Take Food?

My mother is 85 with several health conditions. She has been in and out of the hospital with infections. The last 2 months she have not been able to eat and have loss a lot of weight. Her physician(s) cannot explain why she is not able to swallow. She has home health and all of her vitals are good. She had an ERCP in January 2015. What are the symptoms relating to the superbug that have been discussed on CBS news