Why is the risk elevated for staphylococcus aureus infection for those on home parenteral nutrition?

Risk of infection. The risk resides with the insertion site of the intravenous catheter. The insertion site is a breach of skin where skin bacteria can gain entrance into the vein. Staph is a skin bacteria. Hence, controlling infection risk requires strict technique and extreme carefulness at the catheter site. Wearing gloves. Purell, Extreme caution with connections.
TPN. Anyone on TPN has a propensity to develop infections due to the high content of glucose. It will not be surprising staph infections occur.