Meningitis Flashcards
What is meningitis?
Inflammation of the two inner meninges (the pia and arachnoid mater) of the brain and spinal cord.
What is encephalitis?
Inflammation of the brain tissue itself.
What are the causes of meningitis?
Infective e.g. bacterial, viral and fungal
Non-infective e.g. certain cancers, autoimmune disorders, and drugs
What is bacterial meningitis?
Differentiate between meningococcal and pneumococcal disease.
Bacterial meningitis is a life-threatening condition that affects all ages, but is most common in babies and children.
Meningococcal disease is infection with Neisseria meningitidis.
- It can result in meningococcal meningitis (15% of cases) or meningococcal septicaemia (25% of cases) or a combination of both (60% of cases).
Pneumococcal disease is infection with Streptococcus pneumoniae (also called pneumococcal). .
What are most common causative organisms of acute bacterial meningitis in children aged 3 months or older and adults?
Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib).
What is the most common caustative organisms for meningitis in neonates?
In neonates the most common cause is Group B Streptococcus (GBS). GBS is usually contracted during birth from the GBS bacteria that can often live harmlessly in the mothers vagina.
Briefly describe Neisseria meningitidis
Note: gram stain, commensal, transmission
Neisseria meningitidis is gram negative bacteria.
URT commensal in ~10% adhering to non-ciliated epithelial cells in nasopharynx and tonsils.
Person-to-person transmission is via droplets and URT secretions.
Briefly describe the various strains of Neisseria meningitidis
Note: vaccination programme
There are 12 capsular groups of meningococci- B, C, W, and Y were historically the most common in the UK, however, after the introduction of the meningococcal C vaccination programme, group B (MenB) now accounts for the majority of cases.
MenB is responsible for the majority of invasive meningococcal disease cases in people aged under 25 years.
Briefly describe Streptococcus pneumoniae
Note: gram stain, commensal, transmission
Streptococcus pneumoniae is a gram positive bacteria.
Some serotypes of pneumococcus may be carried in the nasopharynx without symptoms, with disease occurring in a small proportion of infected people.
Direct person-to-person contact via respiratory droplets.
What are the risk factors for meningitis?
- Young age
- Old age >65 years
- Immunocompromised state (e.g. HIV infection or chemotherapy)
- Incomplete immunisation
- Crowding
- Exposure to pathogens
- Sickle cell disease
- Cranial anatomical defects
- Cochlear implants
What are the common non-specific signs and symptoms of meningitis?
- Fever
- Vomiting/nausea
- Lethargy
- Irritability/unsettled behaviour
- Ill appearance
- Refusing food/drink
- Headache
- Muscle ache/joint pain
- Respiratory symptoms/signs or breathing difficulty
What are the common specific signs and symptoms of meningitis?
- Non-blanching rash
- Stiff neck
- Capillary refill time of more than 2 seconds
- Cold hands and feet
- Unusual skin colour
- Shock and hypotension
- Leg pain
- Back rigidity
- Bulging fontanelle
- Photophobia
- Kernig’s sign
- Brudzinski’s sign
- Unconsciousness or toxic/moribund state.
- Paresis
- Focal neurological deficit including cranial nerve involvement and abnormal pupils
- Seizures
How may neonates and children appear with meningitis?
Neonates and babies can present with very non-specific signs and symptoms such as hypotonia, poor feeding, lethargy, hypothermia and a bulging fontanelle.
What is Kernig’s sign?
Unable to fully extend at the knee when hip is flexed.
What is Brudzinski’s sign?
Person’s knees and hips flex when neck is flexed.
What are the features of shock?
- Capillary refill time of more than 2 seconds, cold hands and feet
- Unusual skin colour
- Tachycardia and/or hypotension
- Respiratory symptoms or breathing difficulty
- Leg pain
- Toxic/moribund state
- Altered mental state/decreased conscious level
- Poor urine output
How may a meningitis rash appear?
Petechial rash: red or purple non-blanching macules smaller than 2 mm in diameter.
Purpuric (haemorrhagic) rash: spots larger than 2 mm in diameter. This may be absent in the early phase of the illness and may initially be blanching or macular in nature.
How can a meningitis rash be assessed?
Consider checking for non-blanching rashes using the ‘glass test’.
- This involves pressing the side of a glass or tumbler firmly against the rash to see if the rash fades or loses colour under pressure.
- A petechial or purpuric rash does not fade.
What does a non-blanching rash indicate?
Meningococcal septicaemia is when the meningococcus bacterial infection is in the bloodstream. Meningococcal refers to the bacteria and septicaemia refers to infection in the blood stream.
Meningococcal septicaemia is the cause of the classic “non-blanching rash” that everybody worries about as it indicates the infection has caused disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages.
Compare and contrast a lumbar puncture from bacterial and viral meningitis
Note: appearance, protein, glucose, white cell count and culture
Tip: it is easier to think about what will happen to the CSF with bacteria or viruses living in it rather than trying to rote learn the results. It makes sense that bacteria swimming in the CSF will release proteins and use up the glucose. Viruses don’t use glucose but may release a small amount of protein. The immune system releases neutrophils in response to bacteria and lymphocytes in response to viruses.
