BACTERIA MENINGITIS FOR UNDERGRADUATE STUDENTS

FOR INTERMEDIATE LEVEL STUDENTS

1. MENINGITIS
Dr Abdu Hussein Mogella

2. Learning Objectives
•Define meningitis
•Describe aetiology and risk factors of meningitis
•Describe mode of transmission of Meningitis
•Describe the epidemiology of Bacterial meningitis
•Identify the clinical presentation of meningitis.
•List the common complications of meningitis.
•Describe the most commonly used tests for the
diagnosis of meningitis.
•Describe the management of meningitis.
•Describe the methods of prevention meningitis.

3. Introduction to Meningitis
•Definition- is an inflammation of the
arachnoid layer of the meninges and the
fluid that circulates, in the ventricles and
sub-arachnoid space (CSF) .

4. Major etiological agents
1.Bacteria
S. pneumoniae, N. meningitidis, gp B
streptococcus
•Post-op or hospital acquired – MRSA, Ps.
Aeruginosa, Mycobacterium tuberculosis
2.Viruses
•Enterovirus, coxsackie virus, echovirus, HSV-2,
Fungi
•Coccidioides, cryptococcus, candida,
Histoplasma
3.Protozoa-
•Toxoplasma, Amoeba

5. Risk Factors for Meningitis
•Age
–The very young and the very old
•Alcoholics
•Neural tube defects
•CNS trauma, or after neurosurgical intervention
•Immunodeficiency for any reason
•Sickle cell anemia
•Cardiac and pulmonary anomalies

6. Bacteria Meningitis
The causes of bacterial meningitis vary with age:
•Infants (< 1 year): E. coli, group-B streptococcus, Listeria
monocytogenous are the commonest causative agents.
•Young children/toddlers (age 1- 6 years ) : Haemophilus
influenza, Meningococcus account for > 50 % of cases
•Adolescents and Adults: Meningococcus, Pneumococcus
are the commonest etiologies
•In immunocompromised hosts and cancer patients:
Listeria, Staphylococcus, Pseudomonas aeruginosa

7. Rout of infection
•Droplet infection through the upper airways: E.g. In
Meningococcus meningitis, with possibly epidemic
spread
•Haematogenous spread: e.g. in Pneumococcus
pneumonia
•Contagious spread from adjacent sites : e.g. in otitis
media , sinusitis
• Direct: e.g. in open head injury

8. Epidemiology
•Bacterial meningitis is the most common form of
suppurative CNS infection.
•In the West due to the availability of vaccines for N.
meningitidis and H. influenza, S.
•Pneumonie has become the leading cause of bacterial
meningitis.
•However, in African and most developing countries,
including Tanzania N. meningitidis is still the leading
cause of bacterial meningitis in adolescents and
adults.

9. Clinical Presentation-1
•Incubation period: the incubation period for
Meningococcal meningitis may range from 1-10
days, but mostly the clinical manifestations occur
within in 2-4 days
•Meningitis may manifest as an acute fulminant illness
that progress rapidly in few hours or as a subacute
infection that progressively worsens over several
days.

10. Clinical Presentation-2
•The classic clinical triad of meningitis is fever,
headache and nuchal rigidity (neck
stiffness) , which are seen in > 90 % of
patients .
•Alteration in mental status can occur in > 75 %
of patients and can vary from lethargy to
comma.

11. Clinical Presentation-3
•Nausea and vomiting are common symptoms.
•Avoiding light (photophobia) is seen in some
patients.
•Convulsion occur in 20-40%
•Rash may occur

12. Meningeal Signs
•Neck stiffness: when head is flexed passively
•Kerning’s sign: when one leg which is flexed at the
hip and knee joints, is passively extended at the knee
joint, the other leg flexes at the knee.
•Brudzinski’s sign: Upon passively flexing the head,
one notices flexion of both legs at the knees
Note: These classic meningeal signs may not be seen in
infants, old persons and patients in coma.

14. Complications
•Brain oedema,
•Hydrocephalus
•Brain abscess,
•Septic vein thrombosis
•Hearing impairment
•Fulminant meningococcal sepsis: Waterhouse-
Friedrichsen syndrome is a clinical
•Disseminated intravascular coagulation (DIC)

15. Diagnostic approach
•History, physical examination,
•Search for possible source of
infection(pneumonia , otitis media , sinusitis , head
injury)
•CSF analysis
•Identify the organism from CSF and blood
(culture, PCR etc.)
•Serologic antibody test : latex agglutination test

16. CSF Finding

17. Differential diagnosis
•Virally caused meningoencephalitis (Coxsackie-,
Echo-, Mumps-virus, HIV, measles, CMV, VZV,
HSV)
•Chronic meningitis : Tuberculous meningitis ,
Cryptococcal meningitis
•Subarachnoid haemorrhage

18. Treatment
•Bacterial meningitis is a medical emergency and
antibiotics should be initiated immediately before the
results of the CSF gram stain and culture are known.
Antibiotics should be given intravenously, at higher
doses
•Benzathine penicillin(IV/IM) 300,000U/kg/day with
a maximum dose of 24MU/day for 10- 14 days, give
4 million units 4 hourly IV in adults

19. If no improvement in 3 days’ give
• ceftriaxone (IV) 2g 12 hourly for 10- 14 days
AND
Dexamethasone (IV/IM) 0.15mg/kg with a maximum
dose of 10mg 8hourly for 3 days

20. Specific Meningitides

21. Viral meningitis
•More common than bacterial meningitis, but less
severe
–Appears much like flu and may have milder
symptoms
•Also known as Aseptic meningitis as bacterial
cultures are always negative
•Common symptoms of viral meningitis include:
–headaches
–fever
–generally not feeling very well

22. Viral Meningitis
•More severe symptoms
– nausea and vomiting, neck stiffness, muscle or
joint pain diarrhea, photophobia
•Common; rarely serious infection of fluid in
the spinal cord or fluid that surrounds the brain

23. Signs and symptoms of viral
meningitis
•Usually occur one week after exposure
•Fever
•Headache
•Stiff neck
•Tiredness
•Rash -Viral exanthem
•Sore Throat
•Vomiting

24. Treatment of Viral meningitis
•Usually clears up in a week or two with no
specific treatment
•Antibiotics are not effective on viruses
•Symptomatic management
–Analgesics, antiemetics, anticonvulsants,
antipyretics

25. Meningococcal Meningitis
•Caused by N.meningitidis
–Habitat: human nasopharynx in 10-25%
–Spread by droplets aerosols
–Occurs in outbreaks
•Potentially severe illness
•If septicemia present, it leads to abrupt obtundation
due cerebral edema and circulatory collapse

26. Meningococcal meningitis
Presentation:
•A petechial rash on the trunk & lower body in 70% of
cases.
–may coalesce into purpura - sign of disseminated
meningococcemia & DIC. Distal extremity necrosis
may also occur.
•Rx is effective as the disease usually occurs in
immunocompetent patients, so the case fatality rate is
relatively low at 3%.
•Common complications: cutaneous scars, amputation,
hearing loss, and renal injury.

27. Treatment and prevention
•Penicillin-resistant strains are uncommon- drugs of
choice are penicillin. Ceftriaxone or cefotaxime
response is also excellent.
•A polysaccharide vaccine has been available for a
number of years & routinely recommended for all
adolescents. It has also been useful in pts with risk
factors such as asplenia.

28. Meningococcal meningitis
•Antimicrobial prophylaxis is recommended for
contact cases
–should be done within 24 hours after exposure
because secondary disease occurs within several
days.
–Rifampicin is given bd for two days, but is
contraindicated during pregnancy.
–One dose of ciprofloxacin or ceftriaxone is an
alternative, and ceftriaxone can be given to
pregnant patients

29. Adjuvant therapy
•Dexamethasone was shown to significantly reduce
morbidity and mortality in S. pneumoniae, but no
effect could be demonstrated for N. Meningitidis.
•Dexamethasone has been shown to reduce hearing
loss in H. influenzae meningitis
•Dexamethasone should be given before or with the
first dose of antibiotic, at a dose of 10 mg IV every 6
hours for 4 days for adults

30. Prognosis and complications
•Death occurs in 25% of cases.
•Complications of the disease include brain
infarction in 25 to 40% due to involvement of
perforating vessels at the base of brain.
•Infarction of the basal ganglia is especially
common.
•Hyponatremia due to hypothalamic involvement
may also occur.

31. CRYPTOCOCCAL MENINGITIS
•Etiology-C. neoformans) or C. gatti)
• Neoformans tends to affect
immunocompromised hosts while C. gatti
which tends to affect immunocompetent
hosts
•Infection-inhalation of airborne encapsulated
yeast from soil contaminated with pigeon
droppings

32. Clinical presentations
•Asymptomatic or self-limited pneumonitis
•Only 2% of HIV+ patients present with pulmonary
symptoms including productive cough, chest tightness,
and fever
•Frequently disseminates in HIV+ population
•Leading cause of meningitis in patients with HIV

33. Investigations
•Serum cryptococcal antigen
• CSF for meningitis
– India-ink stain
–Cryptococcal antigen test
–Culture to confirm
CSF
•High opening pressure >40cm H20

34. Treatment

35. Thank You for Listening