Bacterial Meningitis

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Introduction

This refers to inflammation of the lepto-meninges as a result of bacterial infection. This condition occurs more frequently in Late-Onset Sepsis compared to Early-Onset Sepsis. It is associated with high mortality because early diagnosis is usually difficult since the early features are non-specific.

Clinical Features

The early, non-specific features include: fever, vomiting, poor feeding and poor activity.

The late features are more specific and these include: hypothermia, tone abnormalities, particularly, hypertonia, high-pitched cry, setting-sun eye appearance, opisthotonus, bulging and tense anterior fontanelle, seizures, apnea and altered sensorium.

Investigations

  • A lumbar tap for cerebrospinal fluid analysis is mandatory. Skip it if the infant has cardio-respiratory instability.
    • Inability to carry out this important investigation must not be a reason to delay empirical antibiotic therapy.
    • Meningitis is diagnosed with cell count greater than 30/mm3, pleocytosis with polymorphonuclear cells, protein greater than 150mg/dl and glucose less than 50% of simultaneously assayed blood glucose.
  • Neuro-imaging studies are required if: (a) fever persists or recurs (b) seizures recur after initial control (c) occipitofrontal circumference is increasing. It will be necessary to exclude subdural and intra-cerebral collections.

Treatment

  • The empirical antibiotic therapy should be tailored to the local pattern of bacterial aetiology of neonatal meningitis.
  • Staphylococcus aureus, Streptococcus pneumoniae and the Gram-negative bacilli are frequently encountered in Nigeria. Therefore, the recommended antibiotics include a combination of intravenous third-generation cephalosporin: ceftriaxone 50mg/kg 12-hourly or cefotaxime 50mg/kg 6-hourly and gentamicin 2.5mg/kg 12-hourly.
  • Intravenous ampicillin 50mg/kg 6-hourly may be useful in places where resistance of organisms to the drug is not remarkable and in known cases of Listeria monocytogenes infection.
  • The duration of antibiotic therapy is 14 days for Gram-positive organisms and 21 days for Gram-negative organisms.
  • Phenobarbitone is recommended through the intravenous route for seizures; 15mg/kg loading dose followed up with 2.5mg/kg 12-hourly maintenance doses. The loading dose could be repeated at 10mg/kg when seizures are difficult to control.
  • Fluid therapy: The current body of evidence is not in favour of fluid restriction for all infants. Critically-ill infants tend to be dehydrated from poor feeding or vomiting and fluid restriction is likely to be harmful – risk of shock and renal shut-down – In such babies. More important is the need to avoid over-hydration (in lieu of the risk of cerebral edema) and that could be achieved by stringent administration of not more than the recommended maintenance fluid requirement.
  • Corticosteroids: Unlike in older infants and children, corticosteroids are presently not recommended for use in neonatal meningitis for lack of evidence of usefulness.
  • Support care: Fluid and caloric balance, blood transfusion for severe anaemia, oxygen therapy and ventilators supports for hypoxaemia.