Answer and explain your answer: antibiotics can treat bacteria or virus causing illnesses?

Answer: Antibiotics treat only bacteria.

Explanation:

Antibiotics are used for the treatment of diseases that are caused by bacteria only. They can't be used for treatment of illnesses caused by viruses.

Antibiotics cannot kill viruses because bacteria and viruses have different mechanisms and machinery to survive and replicate. The antibiotic has no "target" to attack in a virus.