microbiology

• •Meningism: Symptoms of headache, neck stiffness and photophobia often associated with meningitis
• qMeningitis: Inflammation of the meninges. Strictly a pathological diagnosis.
• Elevated CSF WCC and protein are normally used as indicators of inflammation
• Meningeal enhancement may be seen on contrast enhanced CTor MRI.
• Meningitis

  A rare condition that derives from systemic infection or peripheral nerve transmission with high fatality rates !
• Meningitis

  •non-infective

  • infective

  notify officer of the local authority on suspicion of meningitis or

  meningococcal septicaemia

  transfer to secondary care facility

  URGENT !!!  Call 999
• Meningitis

  Give antibiotic if suspicion when you have antibiotics when they are the right ones and there are no anticipated risks

  then administer them

  (particularly to children and young people)

  i.e., benzylpenicillin
• Blood brain barrier (BBB):

  A diffusion barrier that impedes the influx into brain parenchyma of certain molecules on the basis of polarity and size

  
• The path to CNS infections - Brain pathway is much thicker/tighter

  A) fenestrations

  B) endothelium

  C) basal membrane

  D) choroid cells

  E) tight junctions

  F) tight junctions

  G) endothelium

  H) basal membrane

  I) astrocyte

  
• The path to CNS infections

  A) thick

  B) apical tight junctions(gap junctions)

  C) yes

  D) no

  E) no

  F) thin

  G) no

  H) tight junctions (ependymal cells of the choroid plexus)

  I) yes leaky

  
• Different microorganisms, different “commuting ways to work”

  
• How to get through the BBB

  A) TRANSCYTOSIS

  B) PARACELLULAR infection

  C) RECEPTORHIGHJACKING

  D) TROJAN HORSE

  
• How to get through the BBB

  A) Cryptococcusneoformans

  B) Trypanosoma brucei

  C) HIV

  D) Neisseria meningitidis

  E) Toxoplasma gondii

  F) Listeriamonocytogenes

  G) Mycobacteriumtuberculosis

  
• Neisseria meningitidis - mediated meningitis

  Often referred to as: Meningococcal meningitis/disease
• Streptococcus pneumoniae - mediated meningitis

  Often referred to as: Pneumococcal meningitis
• meningitis

  •UK: leading cause of death in early childhood
• •main cause of meningococcal meningitis per capsule type has changed over time

  •pathogen replacement

  
• meningitis's

  •young children and the elderly are predisposed

  •different strains (capsular types) appear to have a differential incidence in selected population groups

  
• babies at most risk

  
• Respiratory microbiota - meningitis

  Meningococcal (meningitis & septicemia) - All

  Meningococcal (meningitis & septicemia) - MenB

  Pneumococcal

  Haemophilus influenzae

  
• Vaginal microbiota - (~10% of women)

  Neonatal group B Streptococcal septicemia

  ( Streptococcus agalactiae )

  
• causative agent frequency

  A) PROTOZOA

  B) FUNGI

  C) BACTERIA

  D) VIRUS

  E) Neisseria meningitidis

  F) HIV infection

  G) Treponema pallidum

  H) Mycobacterium tuberculosis

  
• Most septicaemias are accompanied by meningitis 

  
• Meningitis -

  A) dramatic

  B) rapid

  C) common

  D) rare

  E) not self limiting

  F) moderate

  G) slow

  H) very common

  I) self limiting

  
• bacterial meningitis

  A) N. meningitidis

  B) GBS

  C) Listeria monocytogenes

  D) S. pneumoniae

  E) Haemophilus influenza

  F) S. aureus

  G) M. tuberculosis

  H) Klebsiella pneumoniae

  I) E. coli

  J) Pseudomonas aeruginosa

  
• Virulence - meningitis

  A) Haemophilus influenza

  B) 1-2 days

  C) Neisseria meningitidis

  D) 6-24 hours

  E) Strep. pneumoniae

  F) acute

  G) sequelae

  H) nasopharynx

  I) droplets

  J) saliva

  
• Fungi & Protozoa - facts

  
• The other guys :  viruses (mild or no symptoms) - Not always possible to identify the virus

  •Herpes viruses:

  •HSV-1 - •HSV-1 less common that HSV-2 (more encephalitis)

  •HSV-2 - •Common cause of recurrent viral meningitis

  •VZV - •Connected to exanthemal illness

  •HHV-6 - •Connected to exanthemal illness; less common

  •In 40% of patients with unknown etiology
• The other guys :  viruses (mild or no symptoms) - Not always possible to identify the virus

  •Mumps - •Most common cause before MMR vaccine

  •Enteroviruses: Coxsackie (B) and Echovirus -

  •Most common cause of viral meningitis

  •Throat, flu-like symptoms, upset stomach/intestine

  •Mostly children

  •Summer and autumn (UK)

  •Transmission through contact

  •Rubella and Measles - •Connected to exanthemal illness
• Risk factors - meningitis

  •enabling access paths to the CNS (e.g., shunts)

  •dysfunction of selected organs (including cancer)

  •exposure (e.g., crowding)

  •selected bacterial infections (e.g., endocarditis, pneumonia)

  
• Bacterial meningitis must be the first and foremost consideration in the DDx of patients - Classic symptoms not common in children or the elderly !!!

  Only in less than 50% of adults
• •The triad - meningitis

  •fever / headache

  •neck stiffness (not so much in children  !!! )

  change in mental status
• •Other symptoms of meningitis

  •nausea and vomiting

  •photalgia (photophobia)

  •back rigidity

  •sleepiness

  •confusion

  •irritability

  •delirium

  •coma

  •seizures (uncommon)

  •neurological disturbances and profound alteration of consciousness – think encephalitis !
• The symptoms - Children

  •fever

  •bulging fontanelles - often absent in bacterial meningitis

  •leg pain, cold hands & feet and abnormal skin colour (12 hrs) - Indications of shock

  •haemorrhagic rash (petechial rash), meningism and impaired consciousness (after)

  •seizures (some children)
• Symptoms : Acute viral meningitis (enteroviruses)

  
• Symptoms : Chronic viral meningitis (enteroviruses)

  
• •The diagnostic challenges in patients with clinical findings of meningitis:

  •can we identify early and treat patients with acute bacterial meningitis?

  •if a CNS infection is suspected subacute or chronic meningitis treatable?

  •can we identify the causative organism?
• •CSF lumbar puncture:

  •Microbiology: Culture; microscopy

  •Cell count (T-cell, monocytes - increase)

  •Biochemistry (e.g., glucose & protein)

  •DNA (PCR) (e.g., N. meningitidis )
• •CSF lumbar puncture:risk of brain herniation (pressure differences):

  •>60 yr old

  •immunocompromised

  •history of neurological disturbances

  DON’T DO IT  IF :

  •reduced consciousness

  •very bad headache

  •frequent fits
• •Blood:

  •biochemistry (e.g., glucose, gases, electrolytes, urea, creatinine, …)

  •CBC (complete blood cell count)

  •coagulation profile (+ platelets)