How can I avoid getting sick from a bacterial illness?

How dangerous is a staph infection? Can I assume that if food smells bad its unsafe to eat and if it smells ok that it is safe to eat? How many types of bacteria are there? What foods are likely to be contaminated by listeria? What foods can give a person a staph infection?
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Jaymie:
Then we found what we needed and I simply asked if that was what my dad wanted and she yelled at me.
(31 July 2016)

Jaymie:
So I stopped and I was really pissed.
(31 July 2016)

Jaymie:
I was walking a little ahead of her and she screamed at me to wait.
(31 July 2016)

Jaymie:
I didn't want to but I got up and did anyway.
(31 July 2016)

Jaymie:
Then today Mary came up to my room and asked if I could go to the dollar store with her which is like a half a block away.
(31 July 2016)

Jaymie:
But my biological sister heard and told my parents so I got in trouble.
(31 July 2016)

Jaymie:
The other day I was telling my best friend how I'm not going to call Mary my sister and she never will be my sister.
(31 July 2016)

Jaymie:
I'm really not okay with the change but when I told my dad that he just yelled at me.
(31 July 2016)

Jaymie:
She never leaves me alone and she acts like she knows everything.
(31 July 2016)

Jaymie:
My dad recently moved his girlfriend and her daughter in. (Were gonna call her Mary) Mary is the same age as me too.
(31 July 2016)