A Rare Occurrence of Amoxicillin-Induced Aseptic Meningitis in a Young Adult: A Case Report

Aseptic meningitis (AM) is characterized by clinical manifestations and laboratory findings indicative of meningeal inflammation, without detectable bacterial pathogens in routine cultures. Drug-induced aseptic meningitis (DIAM) is a rare but important etiology. It has been associated with certain drugs, including intravenous immunoglobulin, antiepileptic drugs, monoclonal antibodies, and antibiotics. Amoxicillin-induced aseptic meningitis (AIAM) is an exceptionally rare variant. We present a case of a 25-year-old female who presented with fever and cough for five days. She was prescribed amoxicillin by her general practitioner (GP) and continued the course for five days. Following this, she began to have severe headaches associated with neck stiffness and photophobia. An urgent lumbar puncture (LP) was conducted, and then a combination of intravenous cephalosporins and acyclovir was started empirically, with a differential diagnosis of partially treated meningitis, possibly bacterial in origin. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis with low protein and normal glucose levels. Both bacterial and fungal cultures were negative. Subsequently, herpes simplex virus infection was ruled out through serological testing. Hence, the antibiotics and antivirals were stopped, and she was initiated on symptomatic management. The patient recalled a similar episode occurring subsequent to the administration of amoxicillin for a respiratory infection, a detail that was also reflected in her medical records. Considering her clinical presentation, CSF findings, and the previous exposure to amoxicillin coinciding with an episode of meningitis, a multidisciplinary team (MDT) involving Neurology proposed AIAM as a likely diagnosis. Furthermore, her rapid recovery following the cessation of the drug confirmed the final diagnosis of AIAM. This case emphasizes the need for early recognition to avoid unnecessary antimicrobial treatment, as well as recognizing AIAM in a patient, which can prevent recurrent occurrences.