'bacillemia' originates from New/Modern Latin and Greek elements, specifically the New Latin 'bacillus' and the Greek suffix '-emia', where 'bacillus' meant 'small rod' and '-emia' meant 'blood condition'.

'bacillemia' was formed in medical New Latin by combining 'bacillus' (Latin, from Latinized form of Greek 'bakḗllos', meaning 'little rod') with the Greek-derived suffix '-emia' (from Greek 'haima', 'blood'), and it entered English usage as the medical term 'bacillemia'.

Initially it denoted the condition of having bacilli in the blood; this core meaning has been retained in modern medical usage.