i) antimicrobial regimen has incorrect dose/route/frequency for intended infectious syndrome, pathogens and/or patient factors ii) length of treatment too short (discontinuation before adequate source control or clinical stability) or too long (prolonged therapy despite documented microbiologic clearance or resolution of symptoms) iii) empiric therapy spectrum too broad or narrow considering possible causative pathogens iv) antimicrobial therapy not tailored/streamlined/de-escalated for microbiology results v) non-infectious syndrome