yes
Both. Some bacterias may be pathogenic while others are quite harmless, and sometimes even useful to its host.
MRSA bacteria are pathogenic, this is the name given to a group of bacteria that belong to the Staphylococcus aureus family of bacteria which have grown resistant to methicillin-type antibiotics....
Pathogenic bacteria cause illness. Non-pathogenic bacteria peacefully co-exist with us and do not cause illness.
Any bacteria that does not cause harm to the subject.
Non-pathogenic bacteria are bacteria that don't cause diseases. The bacteria that ferment yogurt are non-pathogenic.