37  Meningitis (bacterial)

37.1 Definition

Inflammation of the meninges due to bacterial infection. The onset of symptoms is classified as acute (symptoms evolving rapidly over 1-24hrs), sub-acute (1-7 days), and Chronic (> 1 week). Infants, children, and young adults are most likely to suffer from bacterial meningitis.

37.2 Incidence/prevalence

An estimated 2.5 million cases of meningitis occur globally each year, with approximately 250,000 deaths.(PATH 2021) In 2023, information from LHIMS, Komfo Anokye Teaching Hospital, Kumasi indicated a rate of 1.5% or 15/1000 admissions through the Paediatric Emergency Unit (PEU) were diagnosed as meningitis. Most of the KATH cases were not confirmed.

37.3 Aetiology

Several different bacteria can cause meningitis. Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis are the most frequent ones. N. meningitidis, causing meningococcal meningitis, has the potential to produce large epidemics. 12 serogroups of N. meningitidis have been identified, 6 of which (A, B, C, W, X and Y) can cause epidemics.(Organization 2021) Viral, fungi and Mycobacterium species can also cause meningitis. This write-up is limited to bacteria.

37.4 Pathogenesis

The bacterial gain access to the central nervous system through

1. Invasion of mucosal surface (respiratory tract) then, hematogenous to the brain;
2. Spread from Para meningeal focus(otitis media, sinusitis); penetrating head trauma, and previous neurosurgical procedure.

Bacterial meningitis is distinguished by the introduction of bacteria into the cerebrospinal fluid (CSF) and the subsequent proliferation of bacteria in this compartment, leading to inflammation both within the CSF and in the brain tissue next to it. By production and/or release of virulence factors into and stimulating the formation of inflammatory cytokines within the central nervous system, meningeal pathogens increase the permeability of the blood-brain barrier, thus allowing protein and neutrophils to move into the subarachnoid space.(Hoffman and Weber 2009)

37.5 Signs and symptoms

Infants: Temperature instability, convulsions, meningeal irritation (stiff neck, positive Kernig’s sign, Positive Brudzinski’s sign), bulging fontanelles and increased head circumference are common and may be late signs. Signs are very non-specific. Examine for spinal or cranial abnormalities

Older children: Fever, headache, photophobia, Changes in mental status (Irritability, lethargy, coma, and confusion), and End organ dysfunction (Heart, Lung, Kidney, Liver). Meningeal irritation (neck stiffness, positive Kernig’s sign), cranial nerve palsies, and purpuric rash – meningococcal meningitis.

37.6 Investigations

Lumbar puncture: White Blood Cells, Red Blood Cells, protein content, Glucose content (2/3 blood glucose), Culture and sensitivity, Serology (latex agglutination test), PCR

Table 37.1: Lumbar puncture findings in different meningitis

Item	Bacterial	Viral	Fungal	Tuberculous
Opening pressure	Elevated	Slightly elevated	Normal or high	Unusually high
Appearance	Turbid	clear	Turbid	Cob-web
Proteins	Very high	Normal	High	High
Glucose	Low	Normal	Low	Low
RBCs	Few	None	None	None
WBCs	>200	<200	<50	20-30
Differential	Polymorphonuclear cells	Monocytes	Monocytes	Monocytes

Blood: Glucose, culture and sensitivity

Imaging: (CT Scan/MRI) helps identify: brain abscesses, meningeal inflammation, infarction, haemorrhages, subdural effusion, focal infections (sinusitis)

37.7 Contraindications

Focal neurologic deficit or signs of increased intracranial pressure, deep coma, protracted seizures, cranial nerve palsy, pupillary dilatation, bleeding disorders, septic lesion at the site of LP.

37.8 Treatment

37.8.1 General and supportive measures

Close cardio-respiratory monitoring, frequent neurologic assessment, strict fluid balance, frequent urine specific gravity assessment, nil per os until neurologically stable, isolate until the organism is known, daily weighing, and frequent BP monitoring may be needed, monitor and treat for (hypoglycaemia, hyponatraemia, Acidosis, Septic shock, DIC, Seizures, Increased intracranial pressure)

37.8.2 Definitive treatment

Ceftriaxone is the drug of empiric choice beyond the neonatal period (cefotaxime is preferred in the first 2 weeks of life). Modify after culture and sensitivity results are available. Look out for focus if the response to antibiotics is sub-optimal. Steroids such as dexamethasone may be used depending on the organism isolated. Anticonvulsants (phenobarbitone, diazepam, and midazolam) and analgesics may also be required.

37.8.3 Prophylaxis

Close contacts especially for patients with Neisseria meningitidis meningitis will need post-exposure prophylaxis preferably within 48 hours. Options are ciprofloxacin or rifampicin.

37.8.4 Vaccines

Vaccines are available for use, especially during outbreaks

37.9 Complications

These include seizures, persistent focal seizures, neurological deficits, cerebral oedema, visual impairment, ataxia, hearing loss, hydrocephalus, cranial nerve palsy, mental retardation, severe behavioural problems, syndrome of the inappropriate release of antidiuretic hormone (SIADH), and vegetative state.

37.10 Prognosis

Even with timely, appropriate treatment, bacterial meningitis can be fatal in 5 to 20% of newborns and 5 to 15% of older infants and children.(Skar et al. 2024)

37.11 Differential diagnosis

Differential diagnoses include cerebral malaria, liver failure, brain abscess, encephalitis, brain tumour, and subarachnoid haemorrhage.

37.12 Sample questions

1. A neonate presented at 24 hours post-delivery with fever, floppiness, and poor feeding. These were your CSF chemistry report

Appearance	Proteins	Glucose	WBCs	Differentials
Turbid	High	low	<50	Monocytes

Which of the following diagnoses is most likely?

1. Bacterial
2. Fungal
3. Tuberculosis
4. Viral

This CSF characteristic is more consistent with the fungal cause of meningitis. There will be a need to investigate immunosuppression.

2. You suspect a 10-year-old presenting with focal seizures and febrile illness had meningitis. You were not able to do a Lumbar puncture. You started treatment with ceftriaxone. Three days into treatment, the child still had a fever (39.7^oC) and focal seizures. What will be your best next step?

   1. Increase the ceftriaxone dose
   2. Modify antipyretic dose
   3. Immediate lumbar puncture
   4. Imaging of the head

   Imaging (CT scan /MRI) will be the best option to help identify the focus of infection especially abscesses.

Practice question

3. You worked as Director of Public Health in a rural facility. There was a sudden increase in the number of students admitted to your facility from a particular secondary school with meningitis. Enumerate the steps you will take to stop the outbreak.

Hoffman, Olaf, and Joerg R. Weber. 2009. “Review: Pathophysiology and Treatment of Bacterial Meningitis.” Therapeutic Advances in Neurological Disorders 2 (6): 401–12. https://doi.org/10.1177/1756285609337975.

Organization, World Health. 2021. “Defeating Meningitis by 2030: A Global Road Map.” World Health Organization. https://apps.who.int/iris/handle/10665/342010.

PATH. 2021. “Toward a World Without Meningitis.” PATH Impact Stories. https://www.path.org/our-impact/articles/toward-world-without-meningitis/.

Skar, Gwenn, Lillian Flannigan, Rebecca Latch, and Jessica Snowden. 2024. “Meningitis in Children: Still a Can’t-Miss Diagnosis.” Pediatrics In Review 45 (6): 305–15. https://doi.org/10.1542/pir.2023-006013.