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.