How is it possible that less than 1 percent of bacteria cause disease?

Answer 1

Because the majority of bacteria you will enounter everyday and have built up a pretty good immune system by being exposed to them. The 1 percent your referring to will be the ones that have mutated and ones that are not found around you all the time.....e.coli can kill but did you know that you have e.coli in your gut..The deadly one, is a different strain of e.coli, the one in your gut is what is known as 'friendly bacteria' as it helps you out. Have you heard of all these yoghurt type drinks, actimel? yakult? They are all good bacteria, which if you take them, will aid digestion and limit the amount of bad bacteria in your gut. Your farts might not smell so bad(bad bacteria) after taking those drinks for a few weeks lol

Answer 2

Most bacteria are harmless or even beneficial to humans. Only a small percentage have the ability to cause disease because they possess specific virulence factors that allow them to evade the immune system and colonize or damage the host tissues. Additionally, the human body has defense mechanisms, such as the immune system, that can help protect against pathogenic bacteria.