Correct use of the comma.

It is completely acceptable to list items with a comma before the and. The only true exception is when it is a pair.
ex:
I went to the bar with John, (and) Bob and Margret.
Bob and Margret are a pair, and are listed together, thus you cannot separate their "and" with a comma, and you should put another "and" before them, though I don't think it's absolutely necessary.
Maybe it is different for American standards. (i.e. lazy standards)