instruction: how many patients underwent a therapeutic antibacterials - aminoglycoside two or more times?
response: SELECT COUNT(DISTINCT t1.uniquepid) FROM (SELECT patient.uniquepid, COUNT(*) AS c1 FROM patient WHERE patient.patientunitstayid = (SELECT treatment.patientunitstayid FROM treatment WHERE treatment.treatmentname = 'therapeutic antibacterials - aminoglycoside') GROUP BY patient.uniquepid) AS t1 WHERE t1.c1 >= 2