Meningitis and encephalitis: Case

This 19-day-old presents with poor feeding, irritability, fever, a bulging fontanelle, and a focal seizure. Infants are the great masqueraders: the absence of neck stiffness never excludes bacterial meningitis. The working diagnosis is neonatal bacterial meningitis until proven otherwise, with herpes simplex encephalitis on the same list because of the focal seizure. ^[1]

Clinical findings

Key findings are the bulging fontanelle, the focal seizure, and fever with irritability. The differential includes bacterial meningitis (group B Streptococcus, Escherichia coli, Listeria monocytogenes), disseminated neonatal herpes, and a metabolic cause of seizure. A full septic work-up is mandatory: blood culture, urine culture, and lumbar puncture when safe, with cell count, glucose and protein, Gram stain, culture, and herpes simplex polymerase chain reaction. ^[1]

NICE: do not lumbar-puncture if there is new focal neurology, including seizures, or a GCS of 9 or less. Give antibiotics immediately; take bloods; stabilise before imaging. The expected bacterial cerebrospinal fluid pattern is a neutrophilic pleocytosis with low glucose and high protein. Gram-positive cocci in chains would point to group B Streptococcus. ^[3][1]