Proper Names

Q. I am confused by how to style bacteria names. Webster’s lists salmonella, streptococcus, and staphylococcus, as well as E. coli. Should they be treated as roman and lowercase (except for E. coli)? The bacterium Listeria is not listed. Is it inconsistent to style this as initial capped and italic if the other names are roman and lowercase?

A. Genus names like Salmonella should be capped and italic; their species are lowercased and italic: Salmonella enterica. However, when popular genus names are used generically (“I think he died of salmonella poisoning”) they are not capped or italicized. Note that you will see genus names all over the Internet lowercased and in roman type, but that is probably because someone didn’t know how to make them italic. Please see CMOS 8.119–8.129 for the treatment of genus and species names and vernacular names.