Question

Why do antibiotics kill bacteria but not viruses?

• A. Antibiotics stimulate the immune system against bacteria but not viruses.
• B. Viruses have a ways of blocking antibiotics.
• C. Viruses are too small to be affected by antibiotics.
• D. Viruses do not have a metabolism.

Answer 1

The correct option is D Viruses do not have a metabolism.

• Bacteria (except in spore stage) must be continuously metabolically active most of the time and thus a bacterial infection can be cured. Viruses are metabolically inert until they enter a host cell and thus they are not susceptible to the actions of antivirals until then. An exception would be drugs that block viral adhesion to host cells, thus preventing their entry.
  
• The virus often hijacks host genome, thus their protein can be closely related to host proteins. So it is difficult to distinguish between host and virus proteins.
• The virus does not have a cell wall as bacteria. Antibiotics stop the making of a cell wall in bacteria. Thus they remain unaffected by antibiotics.

So the correct answer is option D.