What type of bacteria does Cipro (ciprofloxacin) kill? Why is it mainly used for? What organ systems is Cipro (ciprofloxacin) used on?

Many possibilities. This sounds like you've found someone's medicine and wonder what she or he has. If so, I suggest you ask! Ciprofloxacin is active against a wide range of bacteria to treat many kinds of infection in almost any organ system. Most common probably is urinary tract infection. It isn't usually used for STDs, in case that's on your mind.