is a bacterial infection contagious
Most bacterial infection are contagious. Unlike those infections caused by a virus, bacterial infection responds to antibiotic treatment. Look here for more information: http://www.mayoclinic.com/health/infectious-disease/AN00652.
No, a bacterial infection is not contagious. A viral infection is the kind that is contagious. This is called a virus.
No, a bacterial infection is not contagious, necessarily. Someone with a bacterial infection in their lungs, is not contagious. However, if a cold caused the bacterial lung infection, the cold could be contagious.