The day to day activities of an infectious diseases pharmacist varies quite a bit depending on where one practices and what one was hired to do. I have been at an institution where the pharmacists primarily were committed to stewardship activities, and they basically told physicians who weren't ID physicians what they couldn't have all day every day (prospective approval for all restricted antimicrobials [our list was long]). Tough job, but our antibiogram looked good compared to most, and patients rarely even dreamed of receiving a carbapenem or extended spectrum beta-lactam/beta-lactamase inhibitors. This also translates into much less use of expensive, often unnecessary medications.
Conversely, I know an ID pharmacist who primarily serves as a member of the ID Consult service, and she meets with an Attending and Fellow every day, sees the patients with them, makes recommendations about therapeutic strategies, helps with follow up, etc. Then there are ID pharmacists who fit into a hybrid of the two distinct job descriptions that were elaborated on above.
If you were well trained and at a good VA or an Academic Medical Center with a strong Pharmacy Department, ID pharmacists are certainly able to be given order (drugs/labs) writing ability. These individuals also sit on relevant committees that are in charge of setting most drug use policies regarding antimicrobials in an institution.
