When writing about bacteria, the binomial nomenclature scheme should be used, i.e. a genus name and a species name. Both parts are conventionally set in italic type.

The genus name begins with a capital but the species name does not.

Examples include Staphylococcus aureus, Escherichia coli and Clostridium difficile. The genus name can also be abbreviated to the initial letter followed by a full point and a space, i.e. S. aureus, E. coli or C. difficile. The species name should not be abbreviated, so avoid C. diff.