Bacterial Meningitis in The Newborn

Bacterial meningitis is a serious medical condition characterized by the inflammation and infection of the leptomeninges, which include the arachnoid mater and pia mater, the protective membranes that cover the brain and spinal cord. This condition is primarily caused by pathogenic bacteria invading the cerebrospinal fluid (CSF) and the subarachnoid space, leading to a range of clinical symptoms and potentially life-threatening consequences if not promptly diagnosed and treated.

• Haematogenous: This is the most common route of infection and often follows late-onset sepsis, occurring in approximately 30% of cases.
• Contiguous: This route is rare in newborns.
• Direct Inoculation: Direct inoculation can occur in cases of neural tube defects.

The causative agents of bacterial meningitis can vary based on geographic location:

• In Temperate Countries: In regions with temperate climates, common pathogens often include:
• Escherichia coli (E. coli)
• Group B Streptococcus (GBS)
• In Our Environment: In our specific environment, which may have different epidemiological factors, the leading pathogens responsible for bacterial meningitis are typically:
• Streptococcus pneumoniae
• Listeria monocytogenes
• Pseudomonas
• Proteus

The symptoms and signs of bacterial meningitis include:

• They are often similar to those of septicaemia.
• Patients tend to be either highly irritable or lethargic.
• Convulsions are frequent in cases of bacterial meningitis.
• Anterior Fontanelle: A notable physical sign is the presence of a full, tense, bulging anterior fontanelle.
• Brudzinksi, Kerning signs, and neck stiffness are not demonstrable in a newborn.

The diagnosis of bacterial meningitis typically involves the following tests and evaluations:

• CSF Analysis:
  • Biochemistry: This includes the examination of protein and glucose levels in the cerebrospinal fluid (CSF).
  • Microscopy: Microscopic examination of the CSF is performed.
  • Culture & Sensitivity: CSF is cultured to identify the causative bacteria, and sensitivity testing is done to determine antibiotic susceptibility.
• RBS (Routine Blood Sugar)

Lumbar Puncture in the Diagnosis of Bacterial Meningitis in Newborns

Lumbar puncture (LP), also known as a spinal tap, is a crucial diagnostic procedure used to assess cerebrospinal fluid (CSF) in newborns suspected of having bacterial meningitis. This procedure helps identify the presence of infection, its causative agent, and guides appropriate treatment. However, performing LP in newborns requires special considerations due to their unique physiology and increased vulnerability to potential complications.

Procedure:

1. Patient Positioning: The newborn is usually placed in a lateral decubitus position or, occasionally, in a seated position with the legs flexed. This position maximizes the space between the lumbar vertebrae.
2. Sterile Preparation: The procedure area is meticulously cleaned and draped in a sterile fashion to minimize the risk of introducing infection.
3. Local Anesthesia: A local anesthetic, such as lidocaine, is administered to numb the skin and underlying tissues at the puncture site. Newborns may exhibit pain responses despite anesthesia, so gentle handling is crucial.
4. Needle Insertion: A fine-gauge spinal needle is carefully inserted between the lumbar vertebrae (usually L3-L4 or L4-L5) to access the subarachnoid space. The needle should be advanced slowly and steadily, with minimal rotation, to avoid damaging the surrounding structures.
5. CSF Collection: CSF is collected into sterile tubes for analysis. The amount of CSF collected is typically around 0.5 to 1 milliliter due to the limited CSF reservoir in newborns.

Two bottles are used to for CSF, one fluoride oxalate bottle for CSF protein and glucose and a sterile plain bottle for MCS.

Another fluoride oxalate bottle is used to collect blood for random blood sugar.

6. Closure: After CSF collection, the needle is removed, and a sterile dressing is applied to the puncture site. Gentle pressure may be applied to prevent CSF leakage.

Contraindications: Lumbar puncture is a relatively safe procedure, but contraindications in newborns include:

• Severe Bleeding Disorders: Newborns with coagulation disorders or thrombocytopenia are at increased risk of bleeding complications.
• Infection at the Puncture Site: If there is evidence of skin or soft tissue infection at the puncture site, LP should be postponed until the infection resolves.
• Increased Intracranial Pressure: In cases of significantly elevated intracranial pressure, LP may be contraindicated to avoid potential herniation.

Findings in Possible Bacterial Meningitis: The analysis of CSF obtained through LP in newborns with suspected bacterial meningitis typically reveals the following findings:

1. Elevated White Blood Cell Count (WBC): Bacterial meningitis is characterized by an increased WBC count in the CSF, predominantly neutrophils. A typical range is 1,000 to 5,000 white blood cells per microliter (µL) of CSF.
2. Elevated Protein Levels: In bacterial meningitis, CSF protein levels are often elevated, typically ranging from 100 to 500 milligrams per deciliter (mg/dL) or higher. CSF protein > 150 mg/dl is suggestive of infection.
3. Decreased Glucose Levels: Bacterial pathogens consume glucose in the CSF, leading to decreased glucose levels compared to normal serum glucose levels. A CSF glucose concentration of less than 40 mg/dL is highly suggestive of bacterial meningitis. CSF glucose is normally about half to one-third of the serum glucose.
4. Positive Bacterial Culture: CSF samples obtained during LP are cultured to identify the causative bacterial pathogen. A positive culture confirms the presence of bacteria and guides antibiotic selection for treatment.
5. Elevated CSF Pressure: In cases of bacterial meningitis, CSF pressure may be elevated due to increased intracranial pressure associated with inflammation and swelling.

Effective treatment of bacterial meningitis in newborns involves the following approaches:

• Specific Treatment: Empirical antibiotics are typically initiated immediately upon suspicion of bacterial meningitis. In newborns, a common choice is a 3rd generation cephalosporin antibiotic e.g. ceftriaxone. The choice of antibiotic may be adjusted based on the causative pathogen identified through CSF analysis.
• Supportive Care: In addition to antibiotics, supportive care is crucial for managing newborns with bacterial meningitis. This may include:
  • Steroids: In some cases, steroids e.g. dexamethasone may be administered to reduce inflammation. It is also known to reduce the risk of deafness. The steroids should be started before or at the same time with the antibiotics.
  • Anticonvulsants: Newborns with bacterial meningitis may be at risk of seizures. Anticonvulsants may be prescribed to manage and prevent seizures. Paraldehyde or diazepam can be used to abort seizure in a newborn. Phenytoin or phenobarbital can be used for long-term managemennt.
  • Fluid Management: Fluid intake should be carefully monitored and restricted to around two-thirds of maintenance levels to avoid excessive intracranial pressure from SIADH.
  • Mannitol: Mannitol, an osmotic diuretic, may be administered in some cases to reduce intracranial pressure. 10% mannitol is used in the newborn at 1g/kg given 4-6 hourly for up to 3 times.
• Monitoring: Daily monitoring of the newborn's head circumference (OFC - Occipitofrontal circumference) is essential to assess for any signs of subdural effusion.

Bacterial meningitis can lead to various complications, which can be categorized as:

• Acute Complications:
  • SIADH (Syndrome of Inappropriate Antidiuretic Hormone)
  • Cerebral Edema (Swelling of the Brain)- features of cerebral edema include recurrent seizures despite antibiotics, deepening unconsciousness, abnormal breathing, Cushing's triad.
  • Cranial Nerve Palsy (Dysfunction of Cranial Nerves)
  • Subdural Effusions (Accumulation of Fluid between Brain and Its Coverings)
  • Ventriculitis (Inflammation of Brain Ventricles)
  • Brain Abscess (Localized Collection of Pus in the Brain)
• Long-Term Complications:
  • Deafness (Hearing Loss)
  • Abnormal Behavior
  • Cerebral Palsy
  • Hydrocephalus (Buildup of Fluid in the Brain)
  • Seizure Disorder (Epilepsy)

Bacterial meningitis is associated with a high mortality rate and long-term morbidity.