Ertapenem-induced encephalopathy in a patient with liver abscess and acute kidney injury.

A man in his late 70s, retired and independent, generally fit and well with a history of normal cognitive function baseline presented with liver abscess and acute kidney injury. He received meropenem 1 g three times a day for 15 days then subsequently changed to ertapenem 1 g one time a day in preparation for outpatient antibiotic treatment. After 2 days of starting ertapenem, the patient developed night-time delirium, decreased orientation and insomnia, loss of appetite, jerking and hallucination. Investigations have been done to investigate the cause of acute delirium, including lumbar puncture, CT brain, MRI brain, repeat CT abdomen and pelvis to monitor the liver abscess, and electroencephalogram but results were all unremarkable. Medication history during admission was reviewed and discontinued one by one the medications that were suspected to have caused the encephalopathy. Two days following the discontinuation of ertapenem, the patient's symptoms improved with a rapid return to his baseline and without neurological deficit.