1510 - Recognizing Ertapenem-Induced Toxicity in Inpatient Rehabilitation: A Case Study

Ertapenem-induced neurotoxicity presenting as confusion and visual hallucinations.

Case Description:

A 72-year-old male with a history of multiple sclerosis, CKD stage III, hypertension, hyperlipidemia, and type 2 diabetes mellitus was admitted to inpatient rehabilitation for debility and functional decline following hospitalization for pyelonephritis, during which he was treated with ertapenem for ESBL E. coli. On rehabilitation hospitalization day three (ertapenem day seven), he developed altered mental status and confusion, progressing to visual hallucinations, despite stable vital signs and absence of fever. Medication review identified baclofen 5 mg three times daily and ertapenem 1 gram daily as potential contributors; baclofen was discontinued without improvement. Laboratory studies, including blood counts, metabolic panel (notable only for stable CKD), and ammonia level, were unremarkable, head CT showed no acute intracranial abnormality, and unremarkable electroencephalogram. On ertapenem day eight, ertapenem was discontinued after consultation with infectious disease, all antibiotics were stopped, and the patient was monitored, with subsequent urine cultures remaining negative.

Discussions:

The patient’s symptoms resolved within seven days, supporting ertapenem-induced neurotoxicity. Common manifestations of ertapenem neurotoxicity include visual hallucinations (36.4%), altered mental status (25.8%), and confusion (22.7%). Complete recovery occurs in approximately 91% of cases, as observed in this patient. The median time to symptom resolution is seven days, with a reported range of 1 to 42 days. Discontinuation of ertapenem remains the primary and most effective intervention for managing ertapenem-induced neurotoxicity. Rehabilitation physicians should maintain a high index of suspicion for medication-induced neurotoxicity in patients with new-onset neuropsychiatric symptoms, as this case highlights the importance of a thorough evaluation for toxic, infectious, and metabolic causes.

Conclusions:

Neurotoxicity is a rare adverse event associated with ertapenem. This patient was at increased risk due to advanced age, renal insufficiency, and pre-existing neurological disease (multiple sclerosis). Ertapenem-induced neurotoxicity typically resolves with prompt discontinuation of the medication.