Final answer:
The administration of contrast agents for radiographic demonstration of the spinal canal is performed intravenously. An antimicrobial for treating a systemic infection can be conveniently administered orally. These routes are commonly used in healthcare settings.
Step-by-step explanation:
The administration of contrast agents for radiographic demonstration of the spinal canal is typically performed intravenously (IV).
When it comes to the home administration of an antimicrobial to treat a systemic infection, an appropriate and convenient route would be oral administration.
These routes of administration, IV and oral, are commonly used for their specific purposes in healthcare settings.