Scientific names ought to be italicised. When referring to the entire genus without a specific species, then italicise the genus and add spp. E.g. Pseudomonas spp. Should be italicized.

Should species names be italicized in references?

You should italicize all species names even in the references.

Should Staphylococcus be italicized?

Medical terms such as Staphylococcus aureus are italicized at each instance, but acronyms for these terms (in this case, MRSA), are always set in roman type. In the passage below, the term Staphylococcus aureus is only used once. After its first mention, the acronym, MRSA, is used in its place.