Simultaneous Late, Late-Onset Group B Streptococcal Meningitis in Identical Twins.

To our knowledge, late, late-onset group B streptococcal (GBS) meningitis in identical twins has yet to be reported. We describe a case of 14-week-old twins who developed fever hours apart and presented simultaneously to the emergency department 2 days later with seizures. Blood and cerebrospinal fluid (CSF) cultures from both infants were positive for GBS. Their clinical courses were highly similar, with magnetic resonance imaging (MRI) demonstrating ventriculitis and subdural empyema, complicated by clinical and subclinical seizures requiring quadruple antiepileptic treatment. The CSF was sterile for both on follow-up lumbar puncture 48 hours after the initial positive CSF culture. Both showed marked improvement on antimicrobial and antiepileptic therapy, with fever resolving after 5 days of therapy, control of seizures, and slowly improving MRI findings. Twin A received a 6-week course of penicillin, whereas twin B received 6 weeks plus an additional 10 days due to persistent left cochlear enhancement consistent with labyrinthitis. Evaluation for an underlying primary immunodeficiency was negative. Genomic analysis revealed that the patients' CSF GBS isolates were essentially identical and of capsular polysaccharide serotype Ia.