MENINGOCOCCEMIA
DEFINITION:
A bacterial infection of the blood caused by Neisseria
meningitidis.
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- children <5 years; peak between 6-12 months
- risk factors:
- season: winter, spring (first 4 months of the year)
- genetic: M > F (3:2); HLA-B27
- route: indirect - aerosolization or contact with respiratory
secretions
- environ: endemic - in temporate & tropical climates-Group
B,C; epidemic - in cyclic waves every 10 years, Group A & C
- social: overcrowding, poor general health & living
conditions, military recruits, gays
- diseases: influenzae, sickle cell disease, splenectomy, CSF
leak immunodeficiencies:
- agammaglobulinemia, selective IgA deficiencies
- complement deficiencies (particularly C5-C9):
- primary - inherited
- acquired - hepatic disease, SLE, multiple myeloma
PATHOGENESIS:
- a gram negative, encapsulated coccus
- at least 13 serogroups based on surface capsular
polysaccharides
- meningococcal disease associated with 5 serogroups:
- A, B, C, and less commonly W135, Y
- carriage rates range from 2-5% (healthy children) to 40%
(gays) to 90% (during an epidemic)
- generally a disease of children who acquire the organism
from an adult carrier, usually in the same family (likelihood of
meningococcemia in a familty contact is 1% (increased 1000x)
- virulence factors: pili, antiphagocytic capsules,
lipopolysaccharides (endotoxins), leukocyte-activating factor,
protein and peptide (IgA) hydrolases (degrade both serum and
secretory IgA)
2. Pathogenesis
- at any one time, 5-10% of healthy individuals carry
meningococci in their nasopharynx and carriage may be transient,
intermittent or chronic lasting up to 2 years
- those persons newly colonized with meningococcus are at risk
- initially colonizes the nasopharynx -> mucosal penetration
-> blood -> organs (meninges, lungs, heart, adrenals, joints,
ears, eyes)
- release of interleukins and tumor necrosis factor with
complement activation -> diffuse vasculitis, DIC, hemorrhage and
necrosis of end organs
- fetus may receive antibodies transplacentally which persist
up to 3-6 months of age; the lowest level of bactericidal
antibody occurs between 6-24 months and thereafter the
antibodies increase linearly until 12 years of age
- both circulating IgG & secretory IgA contribute to host
defences
CLINICAL FEATURES:
- upper respiratory tract infection
- fever, malaise, myalgias, arthralgias, headache,
nausea/vomiting, abdominal pain
2. Fulminant Disease
- petechial, purpuric, or morbilliform lesions
- septic shock (hypotension)
- disseminated intravascular coagulation (DIC)
- mortality rate: 15-20%
3. Complications
- fever, malaise, headache, nuchal rigidity, nausea and
vomiting, altered consciousness, coma
2. Others
- acute bilateral deafness, acute cerebellar ataxia, brain
abscesses, diabetes insipidus, encephalitis, hemiparesis,
hydrocephaly, neuropathies (peripheral & cranial nerves
3,4,6-8), quadriparesis, seizures, SIADH, subdural
effusions, spinal cord infarction, subarachnoid hemorrhage,
transient hemiballismus (infants)
- conus medullaris syndrome
2. Respiratory
- pneumonia, pleural effusions, empyema, abscesses, ARDS
3. Cardiovascular
- myocarditis, endocarditis, pericarditis (+/- tamponade),
- heart failure
4. Renal
- oliguria -> acute renal failure, renal infarcts
5. Others
- peritonitis
- arthritis (knee), bony infarcts -> skeletal deformities,
epiphyseal avascular necrosis, epiphyseal-metaphyseal defects
- secondary infection, gangrene, necrosis
- episcleritis, conjunctivitis, endophthalmitis,
panopthalmitis, periorbital cellulitis, retinal detachment
- Waterhouse-Friderichsen syndrome (adrenal hemorrhage)
INVESTIGATIONS:
- blood, CSF, urine, skin lesions, nasopharynx, oropharynx
- culture medium, latex agglutination, CIE to capsular
antigens
- blood cultures are positive in 75% of cases
2. Serum
- elevated ESR, C-reactive protein
- leukocytosis
- DIC - elevated PT, PTT, D-dimer
- decreased fibrinogen, platelets
- CH50 screen (to look for specific complement deficiencies)
- low plasma cortisol (bilateral adrenal hemorrhages)
3. CSF
- acute bacterial meningitis (low glucose, high protein, high
WBC with polymorphs >90%; median count of 1,200)
- gram stain and culture are positive in over 90% of patients
with meningitis
4. Urinalysis
MANAGEMENT:
- treatment for shock (dopamine), DIC (FFP), acute renal
failure
2. Medications
- treatment of choice
- 300,000 U/kg/day IV q4h (max. 24 million units/d) or
- 40,000 U/kg/dose IV q4h
2. Cephalosporins
- 200 mg/kg/day IV q8h or 50 mg/kg/dose IV q6h
2. Ceftriaxone
- 500 mg/kg/dose IV q12h
- antibiotics for 7 days
2. Corticosteroids
- for immune-complex disease
- for adrenal hemorrhage and insufficiency
3. Chemoprophylaxis
- household, school, and daycare contacts
- should be given within 24 hours of diagnosis of primary case
- drug of choice
- eradicates carriage in 60-90% of individuals although
10-25% will develop resistant strains
- 10 mg/kg/dose po q12h x 48 hours
- will develop reddish urine and tears; do not wear contact
lenses during treatment
2. Ceftriaxone
- single 125 mg IM injection
4. Meningococcal Vaccines
- monovalent ©, bivalent (A+C), quadrivalent (A,C,Y W135)
- there is no effective vaccine available against Group B
- in children less than 2 years of age, Group A vaccine
requires two doses
- vaccine may be advocated when there is a spread of
meningococcemia beyond a small, confined group who have received
prophylaxis
5. Poor Prognosticators:
- hypotension, coma, absence of meningismus, hypothermia,
rapid appearance of petechiae (1 hour), end organ failure
respiratory, cardiac, renal), rapid progression of rash
2. Laboratory
- leukopenia (<5,000)
- thrombocytopenia (<100,000)
- absence of CSF pleocytosis in presence of bacteria
- low fibrinogen
- low ESR
|