yes it is infectious. I have studied this due to my baby son having severe eczema and is always infected. There are 2 types one being the strep bacteria. Anyway this is naturally found on the surface of the skin and is harmless. but if the skin is broken it can get inside and lead to infection. it is often found in the nose so getting a nose spray from your doctor may help. also Antibiotic creams and Antibiotics may help. It is highly infectious and you have to clean everything, do not share towels etc and it can be passed on by touch. However it is unlikely to be passed on to someone without Acne or eczema unless there was saliva contact.
I hope this helps you.

I use oregano essential oil diluted in a carrier oil, such as castor oil (believe it or not!) to heal and keep the bacteria at bay. It works very well - I didn't know I was experiencing impetigo again (thought it was adult acne), but when I saw the yellow crust, I recognized it from the periodic outbreaks I had in childhood.