Bacteria are all around us. It is one of the most resilient species that has survived all sorts of physical and environmental challenges through the course of its existence. There are harmful and beneficial bacteria. Both could actually live in your own body but when the bad bacteria increases in number or proliferates too much, then your bodyâ€™s tendency is to fight back. When this happens, your immune system becomes active and sends signals to you that it is presently undergoing a battle. These signals are already telling you that you have a bacterial infection.