Exactly what happens during fatal infection?

Hi, Teddy. I'm in a hurry to leave, so I'll have to make this short, but I'll do my best to quickly explain what I know. The bacteria gets in through the cut, and starts spreading into the surrounding tissue and into the bloodstream. Then the bloodstream carries the bacteria into all the different organs of the body, and the bacteria starts growing throughout the heart lungs, etc. The doctors try one antibiotic, and then another and then another, but they can't seem to find the right antibiotic to kill this particular bacteria. To make matters worse, a bad side effect of the antibiotics, is that antibiotics kill the good bacteria that you have in your intestines, which further weaken your system. At this point, the bacteria is so overgrown throughout your entire body, that no amount of antibiotics is strong enough to kill the gigantic society of bacteria that has taken over your blood and every organ in your body, so you die. That's kind of what happened to my aunt a few months ago (she was in her 60's and appeared healthy on the outside), but her infection began with a tear in her colon (caused by chronic constipation), and the intestinal bacteria escaped through the tear, infecting all the rest of her organs, and she died within a few days. Also, last year, my sister-in-law (in her 30's) got a bacterial infection, from a scratch on her leg, and had to spend a few days in the hospital before they finally found the right antibiotic to kill the bacteria. It happened because she was visiting a 3rd-world country, and the bacteria that got into her cut, was one that her body wasn't normally immune to, since it's not found in America.