Staphylococcus aureus and Escherichia coli.

This is a mixed smear of two different types of bacteria. The round purple ones are Staphylococcus aureus and the pink, short rods are Escherichia coli.

Notice that the staphylococci are clustered together similar to a bunch of grapes. This is where we get the arrangement called staphylo -  and it is also how this bacterial genus was named.

We capitalize and italicize Staphylococcus when we are speaking of the genus but do not when we are speaking of the cellular arrangement. This is the same for Bacillus (the genus) and bacillus the cellular arrangement.