Central nervous system toxicity associated with ertapenem use

To report stroke-like symptoms and unusual central nervous system adverse effects in 2 elderly patients receiving ertapenem.

Two patients ≥70 years of age experienced unusual mental status changes while receiving ertapenem. Patient 1 developed garbled speech and miosis 1 week after starting appropriately dosed ertapenem (1 g/day) for sacral osteomyelitis. Symptoms resolved upon ertapenem discontinuation but recurred upon rechallenge. Patient 2, a cachectic male with acute renal insufficiency, became delirious and progressively obtunded 5 days after starting ertapenem 1 g/day. Nine days after initiation of therapy, he required intubation and mechanical ventilation; ertapenem was discontinued at that time. Within 2 days of ertapenem discontinuation, his mental state cleared and the ventilator was removed.

Carbapenems, including ertapenem, have been implicated in causing central nervous system toxicity, including hallucinations and seizures. However, published reports of other, nonseizure-related central nervous system events are limited. Considerable resources were expended on extensive medical interventions before ertapenem was identified as a potential cause of the delirium in our patients. When applied to our patients, the Naranjo probability scale indicated a highly probable relationship for patient 1 and a probable relationship for patient 2 between the adverse effects and ertapenem use.

Clinicians should be cognizant of ertapenem's potential to induce profound changes in mental status that may mimic other conditions in elderly patients.