Meningitis & N. meningitidis Flashcards
Explain N. meningitidis.
Neiserria meningitidis is meningococcus found in upper respiratory tract as a commensal.
It adheres to non-ciliated epithelial cells in the nasopharynx and tonsils.
Explain N. meningitidis transmission.
Person to person via droplets or upper resp tract secretions.
Most strains are harmless but induce immunity.
The pathogenic, virulent strains are mostly encapsulated and have the potential to cause septicaemia and meningitis.
Serogroups A, B, C, W and Y account for nearly all invasive forms.
Epidemiology of N. meningitidis.
< 2 years of age and around 18 years.
Incubation is 2-7d.
Risk factors such as complement system defects, hyposplenism and HIV.
Presentation of N. meningitidis.
Meningitis
Meningococcaemia
Explain presentation of meningitis due to N. meningitidis.
Main proliferation of the bacteria is in the CSF.
There is an insidious onset with malaise, nausea, headache and vomiting.
Later in the meninginism there is headache, vomiting, nuchal/back rigidity, photophobia and altered consciousness.
Complications of meningitis due to N. meningitidis.
Sensorineural hearing loss
Impaired vestibular function
Epilepsy
Diffue brain injury
Explain meningococcaemia due to N. meningitidis.
The symptoms depend on the amount of circulating bacteria in the blood.
Mild disease presents with fever, macular rash but no signs of shock.
Severe disease causes pyrexia and septic shock within 6 to 12h due to rapidly escalating endotoxin levels.
There is circulatory failure and coagulopathy with skin haemorrhage.
Thrombosis of extremities/adrenals, AKI, ARDS.
Complications of meningococcaemia due to N. meningitidis.
Amputation
Skin necrosis
Pericarditis
Arthritis
Ocular infection
Pneumonia (Y and W)
Permanent adrenal insufficiency
Investigations of N. meningitidis.
Intra and extracellular diplococcia on microscopy of CSF/blood/skin lesions.
PCR of CSF/blood/skin lesion.
Treatment of N. meningitidis.
Do not wait for confirmation if meningitis or meningococcal sepsis are possible diagnoses.
Urgent antibiotics treatment of benzylpenicillin, ceftriaxone.
Cefotaxime, chloramphenicol and meropenem are also bactericidal.
Prevention of N. meningitidis.
Routine infant vaccination against capsular group C in UK.
Capsular group B vaccine in UK infants since 2015
Quadrivalent ACWY vaccine at age 14 and if high-risk travel.
Additional B, C, ACWY doses if hyposplenism and complement deficiency.
Prophylaxis can also be given if in close contact with infected.
If a non-blanching rash is present, what intervention should be done?
Give Benzylpenicilline 1.2g IM/IV before admitting.
Organisms causing meningitis.
Meningococcus or pneumococcus.
Less commonly H. influenzae, Listeria monocytogenis, HSV, VZV, enteroviruses, CMV, Cryptococcus or TB
If immunocompromised, e.g. HIV +ve, organ transplant and malignancy.
Differential of meningitis.
Malaria
Encephalitis
Septicaemia
Subarachnoid
Dengue
Tetanus
Early features of meningitis.
Headache
Fever
Leg pains
Cold extremities
Abnormal skin colour
Later features of meningitis.
Meninginism - neck stiffness, photophobia, Kernig’s sign, Brudsinzki’s sign.
Decreased GCS and coma
Seizures, +/- focal CNS signs +/- opisthotonus
Non-blanching petechial rash.
Shock with prolonged capillary refill time, DIC, decreased BP
Signs of disease causing meningitis.
Zoster
Cold sore/genital vesicles (HSV)
HIV signs of lymphadenopathy, dermatitis, candidiasis and uveitis.
Bleeding +/- red eye in leptospirosis.
Parotid swelling in mumps
Sore throat +/- jaundice +/- nodes (glandular fever)
Splenectomy scar
Management algorithm of suspected bacterial meningitis and meningococcal sepsis.
ABCs
IVI + Fluid resus
Check and correct blood glucose
Then assess whether the patient is meningitic or septicaemic.
Management algorithm of meningococcal sepsis.
Such as shock, prolonged capillary refill, cold hands and feet as well as low BP.
Also evolving petechial rash.
Get ICU help;
Take blood cultures
IV antibiotics
Airway support/pre-emptive intubation
Fluid resus/ionotropes/vasopressors and aim for MAP > 70 mmHg and urine output > 30ml/h
Delay LP investigation until stable.
Management algorithm of meningitic meningitis.
Such as neck stiffness and photophobia without the shock.
Take blood cultures
Assess whether there is signs of increased ICP or midline shift of brain. (Papilloedema, uncontrolled seizures, focal neurology, GCS 12 or less)
If Yes;
Get ICU help;
IV antibiotics
Dexamethasone 10mg IV
Airway support
Fluid resus
Delay LP until stable
Nurse at 30C
If No;
Get senior help;
Perform an LP within the hour
IV antibiotics pre-LP if the LP is delayed > 1h
Dexamethasone 10mg IV
Subsequent therapy of meningitis.
Discuss antibiotic therapy with microbiology and adjust based on organism and local sensitivities.
Maintain normovolaemia with IVI if needed.
Isolate for 1st 24h
Inform public health
Explain the regimen of initiating early antibiotics.
Take blood cultures first.
Perform LP prior to an antibiotic only in patients wihout any evidence of shock, petechial rash, or raised ICP.
Consult local policies and seek advice.
Empirical options of antibiotics include ceftriaxone 2g/12h IV add e.g. amoxicillin 2g/4h IV if > 60 years or immunocompromised.
Other investigations in meningitis.
U&Es
FBCs
LFTs
Glucose
Coagulation
Throat swabs
CXR
Consider HIV and TB tests if relevant.
Prophylaxis of meningitis.
In those of household contacts in droplet range, those who have kissed the patient’s mouth.
Give ciprofloxacin 500mg PO 1 dose
Normal values are
5 or less lymphocytes/mm3
No neutrophils
Protein 0.15-0.45 g/L
CSF glucose 2.8-4.2 mmol/L
Treatment of viral meningitis
Often milder and might not even require any specific treatment but only supportive.
If it does get bad -> Aciclovir for HSV meningitis
Explain investigations and treatment of meningitis
Ideally a blood culture and a lumbar puncture for cerebrospinal fluid (CSF) should be performed prior to starting antibiotics however if the patient is acutely unwell antibiotics should not be delayed.
Send blood tests for meningococcal PCR if meningococcal disease is suspected. This tests directly for the meningococcal DNA. It can give a result quicker than blood culture depending on local services and will still be positive after the bacteria has been treated with antibiotics.
There should be a low threshold for treating suspected bacterial meningitis, particularly in babies and younger children. Always follow the local guidelines however typical antibiotics are:
< 3 months – cefotaxime plus amoxicillin (the amoxicillin is to cover listeria contracted during pregnancy from the mother)
> 3 months – ceftriaxone
Steroids are also used in bacterial meningitis to reduce the frequency and severity of hearing loss and neurological damage. Dexamethasone is given 4 times daily for 4 days to children over 3 months if the lumbar puncture is suggestive of bacterial meningitis.
