Penicillin Psychosis in Later Life: Hoigne's Syndrome Revisited

Case Report

A 63-year-old woman was admitted to an acute psychiatric ward following a 1-week history of sleep disturbance and a 3-day history of seeing “unusual things” such as beetles on the floor and people in her bedroom. She also reported hearing the telephone ringing when her husband could not, and she was seen by her husband talking back to “imaginary people.” A week prior to admission, she had been prescribed amoxicillin 250 mg tid for a urinary tract infection, but there had been no other changes in medication or other acute physical illnesses during this time.

She had been admitted as an inpatient 5 years previously following the administration of amoxicillin for treatment of another urinary tract infection, at which time a diagnosis of paranoid psychosis was made. This had resolved without psychotropic drug treatment within 3 days of discontinuing the antibiotic. She had a history of hypertension, but no history of stroke, epilepsy, head injury, or alcohol misuse. She was a nonsmoker. Her medication on admission was atenolol 100 mg, chlorthalidone 25 mg, and aspirin 75 mg.

On mental status examination, she was well, alert, and cooperative but distractible. She reported hearing voices calling her name; these were fleeting and nonthreatening. On cognitive testing, she scored 21/30 on a screen of cognitive function (Mini-Mental State Examination), losing points for poor registration and concentration. On physical examination, her pulse was 70 and regular, blood pressure 150/100. There were no abnormalities on respiratory or abdominal examination and no focal neurological signs.

Full blood count, plasma viscosity (including erythrocyte sedimentation rate and C-reactive protein), urea and electrolytes, serum phosphate, calcium, magnesium, and liver function tests were all within normal limits. Thyroid function tests and cholesterol and triglyceride levels were similarly unremarkable, and an autoantibody screen was negative. An MRI scan showed multiple subcortical areas of increased signal intensity on T₂-weighted images. Over the next 3 days, her psychotic symptoms resolved completely without psychotropic medication.