Good point, even if it's not exactly related to the topic here.There are some early reports coming out that indicate that this is not true. Kids in developed countries (some more than others) have obesity levels never before seen, and this is causing health issues and premature deaths. Some of these reports are indicating that this generation may be the 1st generation that lives a shorter lifespan than their parents.
Besides, not all bacteria are bad. There are good bacteria inside you. There are bacteria in your intestines. You eat bacteria when you eat yogurt. That's why the doctor asks you to eat yogurt with your antibacterial prescription.
It most certainly can. The bacteria in your body are only good when they're in the exact place they should be. Infact, it's the most common infection scenario (particularily urinary tract infections by e.coli from the bowel). It's not true that you can't make yourself sick (and most women will during their life).But, well, if it came out of you in the first place, it's not likely going to make you sick if it goes back into you. But someone else might have...