All bacterial and many viral genes are italicized. Serovars of Salmonella enterica are not italicized. For organisms other than bacteria, fungi, and viruses, scientific names of taxa above the genus level (families, orders, etc.) should be in roman type.

Should enterococci be italicized?

Yes: when a Latinized genus name appears on its own, it must be italicized (like a species or subspecific name).

How do you write the name of a microorganism?

The genus name is capitalized and the species is lower case. The names should be italicized or underlined in text. Once the complete name of a microorganism has been written out once, the genus name can be abbreviated to just the capital letter provided there is no confusion with other genera.