A Rare Case of Late-Onset Ertapenem-Induced Encephalopathy

Abstract

Encephalopathy is a rare side effect associated with carbapenem antibiotics, typically presenting within one week of initiating treatment. It is almost exclusively seen in patients with poor renal function. We present a case of a middle-aged male with a history of cerebral vascular accident and normal renal function admitted for agitation, delirium, and insomnia more than two weeks after starting ertapenem to treat osteomyelitis. He was empirically treated for meningitis on admission, and ertapenem was discontinued. After an extensive negative workup for infectious and neurological etiologies of encephalopathy, a presumptive diagnosis of ertapenem-induced encephalopathy was made. The patient returned to his baseline mental status five days after discontinuing ertapenem. The nature of his neurological symptoms and timely resolution after stopping ertapenem is consistent with ertapenem-induced encephalopathy and represents a notably delayed symptom onset compared to previously described cases.

Keywords: drug-induced encephalopathy; drug-reaction; ertapenem; ertapenem induced encephelopathy; ertapenem side-effect.

Figure 1. Representative segment of electroencephalogram recording.

The above seven-second epochs were collected using a standard 10-20 electrode arrangement of continuous electroencephalogram (EEG) with accompanying video monitoring. The patient was under continuous propofol sedation at the time of the EEG. The EEG depicts brief one-second bursts of alpha and beta frequencies (blue arrows) on a background of diffuse suppression with low-amplitude delta slowing (red arrows), consistent with severe global encephalopathy or sedation.