Patients who had received either once daily or conventionally administered aminoglycosides. Patients were excluded from the study if they had a creatinine clearance level of less than 30 ml/min (1.8 L/h), were pregnant, were neonates, were being treated for endocarditis, had febrile neutropenia, leukaemia, or cystic fibrosis or had received a single prophylactic dose of an aminoglycoside before surgery or a diagnostic procedure.