Isolation of Neisseria meningitidis Serogroup B from Urine in a 74-Day-Old Infant: A Case Report.

Neisseria meningitidis is a major cause of invasive bacterial disease in infancy, usually presenting as meningitis and/or septicemia. Initial isolation of this organism from urine is exceptionally rare, particularly in young infants. We report a 74-day-old previously healthy infant who presented with fever without an apparent source. Urine obtained by sterile suprapubic aspiration unexpectedly grew N. meningitidis serogroup B. Blood culture subsequently confirmed invasive meningococcal disease, whereas cerebrospinal fluid (CSF) culture and multiplex PCR were negative despite pathologic CSF findings. The urinary isolate was therefore interpreted as probable secondary hematogenous seeding rather than primary urinary tract infection. The patient received ceftriaxone, with temporary escalation to meropenem because of persistent fever; neuroimaging excluded intracranial complications. Complement screening (50% hemolytic complement, CH50) was normal, and the infant recovered fully. This case illustrates an unusual microbiological presentation of probable invasive meningococcal disease, and highlights the importance of promptly interpreting unexpected culture results in febrile young infants.