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what are the 3 most common causes of bacterial meningitis?
- neisseria meningitides
- streptococcus pneumoniae
- haeomophilus influenzae
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which investigation can give an early clue of which one of the 3 primary pathogens is causative?
gram stain can differentiate between the 3
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how do you define a neonate?
birth to 28 days (4weeks)
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what are the commonest causes of neonatal meningitis?
- Group B streptococcus
- E coli, other coliforms
- Listeria monocytogenes
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which organism would cause a more chronic meningitis?
TB meningitis
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what are the 3 main causes of meningo-encephalitis?
- spirochaetes:
- leptospira
- Treponema pallidum (syphilis)
- borrelia burgdorferi (lyme)
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what are the commonest causes of viral meningitis? which group and name 3 in that group
- ENTEROVIRUSES
- 1. echoviruses
- 2. coxsackie virus A & B
- 3. poliovirus
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which herpes virus is more assoc with enceph and which with meningitis?
- HSV1: encephalitis
- HSV2: meningitis
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which virus that causes parotid gland problems can also cause enceph?
paramyxovirus that causes mumps can become complicated and cause enceph
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which viruses cause meningo-encephalitis? (4)
- HSV1
- arbovirus - tropical
- rabies virus (fatal)
- MMR virus
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which is the main fungus meningitis? who? give full name of fungus
- cryptococus neoformans
- HIV immunocompromised
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name 3 causes of protozoal meningitis?
- amoebe:
- naegleria
- acanthamoeba
- other: toxoplasma gondii
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what has acanthamoeba been associated with?
- keratitis
- meningitis
- assoc with contact lens fluids (when weren't sterile)
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what does normal CSF look like?
clear
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what is normal range for CSF lymphocytes ?
0-5/mm3
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how much protein is in normal CSF?
0.15-0.4 g/l
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how much glucose?
2.2-3.3 mmol/l
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how much glucose in CSF should there be in relation to blood glucose?
CSF glucose should be 50% or more of blood glucose
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in a neonate how many PMN are normal?
up to 15-30 polymorphs as BBB is not fully established so get leakage of WBC into neonatal CSF
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what does the CSF look like in bacterial meningitis? what is change in WBC?
- turbid
- increase in polymorphs 100-2000
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in peripheral blood, what is rough ratio of RBC to WBC?
1 WBC to 500 RBC
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in CSF if there were 15,000 RBC and 60 white cells is that normal proportion or something worrying?
-
what happens to protein levels in bacterial meningitis and why?
- increases 0.5-3.0
- bacterial proteins
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what happens to glucose in bacterial meningitis?
- falls precipitously
- because bacteria are using the glucose as energy source for multiplication
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what is the other name for viral meningitis?
asceptic meningitis
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what does the CSF look like in viral meningitis? what is change in WBC?
- clear or slightly turbid
- mainly lymphocytes 15-500
- but polymorphs may predominate in ACUTE STAGE
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what happens to protein levels in viral meningitis and why?
- not that high as active replication inside the CSF is NOT happening
- but there are some viral proteins liberated into the CSF so marginally higher 0.5-1
-
what happens to glucose in viral meningitis?
- as virals are intracellular organisms they use the cell machinery and so don't use up glucose
- glucose levels stay normal (2.2-3.3)
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what is the differential for viral meningitis? 2
- 1. partially treated bacterial meningitis
- 2. brain abscess
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what does the CSF look like in TB meningitis? what is change in WBC?
- CSF: clear, slightly turbid, fibrin clots in CSF
- cells: mainly lymphocytes, also some polymorphs
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what Ix would you want if suspect TB meningitis?
- auramine stain
- suspect on: duration of illness, travel, ethnic origin
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what is the main thing to remember in TB meningitis when looking at CSF?
- protein is very HIGH as organism has a protein rich coat
- 1.0-6.0
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what happens to glucose in TB meningitis?
falls as organism uses it to grow
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what is differential for TB meningitis?
- 1. brain abscess
- 2. cryptococcal meningitis
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what is special about the crying in a baby with meningitis?
- incessant
- doesn't stop when you pick it up (whereas would if just hungry)
- when pick up, jiggles head and irritate membranes more so crying gets worse when pick up
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on examination, what are signs in a baby to pick up for meningitis?
- fever
- rash
- bulging fontanelles
- crying when head movement
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why would a child get conjunctival haemorrhage in meningitis? what do you need to do?
- earliest phenomenon of DIC in a meningococcal infection
- check for non-blanching rash: leaking of blood from small blood vessels in skin, also happening in conjunctiva
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what are the 2 peaks of meningococcal meningitis? why?
- 5-6 months
- 15-25 years age - university
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how would you describe meningococcus on gram stain and microscopy?
meningococcus: gram -ve, intracellular diplococci
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how does meningococucs spread?
- airborne transmission
- close contact
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when are the 2 peaks of meningococcal meningitis and why?
- at 5-6months: creche or nursery
- 15-25 university: crowding of students in closed spaces, military barracks, large events - rebreathing of air in closed spaces
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how do some meningogoccal meningitis present initially?
- flu like illness due to
- viral flu which encourages the organism with colonises airways to penetrate through an inflamed mucosa directly thought cribriform plate.
- (or via bloodstream)
-
which blood tests do you do in suspected meningitis?
- FBC: WCC count, platelets
- CRP
- coagulation screen: DIC in meningococcal and pneumococcal
- blood cultures
- give abx then LP
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what are the contraindications to LP?
- 1. raised ICP
- 2. rash - rapidly spreading purport as shows DIC and means low platelets
- 3. abnormal coagulation screen
- 4. seizures
- 5. severe respiratory compromise - must secure airway first
-
when doing an LP, what 2 things should be notes?
- 1. opening pressure
- 2. when hold CSF up to light - clear or turbid with pus?
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what are the signs of raised ICP?
- 1. neonate: bulging fontanelles
- 2. cushing's reflex: bradycardia with hypertension
- 3. fluctuating GCS
- 4. focal neurology eg hemiparesis
- 5. poorly responsive pupils, papilloedema
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what is single most important factor that predisposes to complications in meningitis?
- delay in giving first antibiotics esp in meningococcal disease because endotoxin released is bad - stimulate whole TNF cytokine cascade
- causes SIRS, DIC, shock
- one arm antibiotic, one arm take bloods. see that is given yourself
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if GP comes to see child at home, what abx they give? why?
- im benpen
- cheap so if goes out of date doesn't matter
- need this one as will treat neisseria meningitides which is the worse one as rapidly evolves and get DIC, endotoxic shock which want to prevent
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what is empirical Rx of meningitis in hospital? why?
- ceftriaxone iv 2g bd
- catch all - treat the top 3 pathogens: meningococcal, pneumococcal and h.influenzae
-
what do you have to do with all meningitis cases in terms of public health?
- all meningitis is statutory notifiable to public health physician
- in UK: CCDC: consultants in communicable disease control
- treating doctor & microbiologists must notify them.
- give them a list of contacts
-
how do you define a contact?
- close household sleeping and kissing contacts
- eg child - mum, dad, siblings
- all kids in creche
- school class
- halls of residence -: everyone in that residence
- hospital staff: mouth to mouth or if intubating had significant aerosol exposure in face
- give prophylaxis to primary contact, not contact of contact
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what is the prophylaxis for meningitis?
- adult: single 500mg tablet ciprofloxacin
- children: rifampicin bd for 2 days - warn secretions may turn orange, don't worry
- pregnant: im ceftriaxone, not cipro in preg
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how quickly do you have to give prophylaxis?
incubation period 5-7 days
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how many groups of meningococcus are there?
-
which is commonest strain of meningococcus in western world?
B
-
which was 2nd commonest strain of meningocooccus?
men c
-
which strain of meningococcus does vaccine cover?
Men C: given as part of universe immunisation of childhood but still need prophylaxis if come across meningitis as no vaccine for men B
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where are men A&C found?
tropics: asia, india, africa near equator
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whose decision is it to re-open school?
with CCDC
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what is the other vaccine given as meningitis prophylaxis?
- quadrivalent vaccine: A C Y W135
- travel vaccine: pilgrimage to Haj, north india…elective
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what is a complication of meningococcal meningitis related to rash
bleeding under skin (ecchymosis when purport coalesce), all tissue superior to that is dead. complications of meningococcal diseases - no blood supply distal to bleeding point so get black digits, black toes - gangrene - not treated quick enough - loss of limb
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what are the risk factors for pneumococcal meningitis?
- 1. age
- 2. splenectomy
- 3. smoking
- 4. alcohol: nutrition is poor, immune status poor
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what is the difference in management of meningococcal and pneumococcal meningitis?
- no contact tracing
- no prophylaxis in pneumococcal
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which cause of meningitis do you add steroids to the management and when?
- only with strep pneumo
- add with 1st dose of abx or within 4 hours
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what is a complication of strep pneumo?
deafness
-
what would strep pneumo look like on culture?
clear area around the bug, which is the capsule
-
what are predisposing factors to neonatal sepsis?
- 1. prolonged labour
- 2. difficult delivery
- 3. PROM > 24 hours
- 4. maternal pyrexia
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what is management of presumed GBS sepsis?
- benzyl penicillin
- add gentamicin for anti microbial synergy
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how to prevent GBS sepsis in neonate?
- screening based: USA not UK. low vaginal swab between 35-38wk gestation look for GBS. if found then get iv ben pen across labour
- risk based strategy: hx of previous baby with GBS sepsis (she is colonised with organism), maternal UTI in this pregnancy with GBS (indicates she's colonised), prolonged ROM, instrumental, maternal pyrexia, prolonged labour, vaginal swab which found GBS
- iv ben pen THROUGHOUT LABOUR as want to saturate fetal tissue with it as it passes through a colonised birth canal
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why does UK follow risk based approach?
- 1. new first time hx of anaphylaxis presents when give ben pen to labour.
- 2. medicalises labour
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what does GBS look like on microscopy?
gram +ve cocci in long chains
-
blood agar plate for GBS?
clear beta haemolysis
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if based on CSF results it looks like viral meningitis, what is your immediate management?
- still give ceftriaxone until you know more - until senior dr has come
- send for bacterial and viral examination - PCR
- commonest virus: enteroviruses
-
what happens in a cell culture infected with ENTEROVIRUS?
- vacuolation of cells
- disruption of smooth monolayer
-
why should children not get herpes virus MENINGITIS?
- because that is much more related to HSV2 which is acquired through genital infection
- don't expect children to get genital infection as usually sexually transmitted
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what is a child likely to get in the brain if they have a coldsore and why?
HSV 1 encephalitis (meningo-encephalitis) as HSV 1 causes oral infections
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which antiviral treats enteroviral group?
none
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if suspect HSV1 or 2 what to give?
ceftriaxone + aciclovir
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how would you differentiate meningitis from meningo-encephalitis?
-
what is more common viral or bacterial meningitis?
viral meningitis more common - but less serious, less sequelae assoc with it
-
what are CSF changes in encephalitis?
- not consistent
- cells - pleomorphic
-
what is encephalitis?
inflammation of the brain due to an infection
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what is the commonest cause of encephalitis?
viral
-
how do viruses gain access to CNS?
- through blood
- or travel within nerve cells (neurones)
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what are the 2 main manifestations of encephalitis?
-
what is primary encephalitis?
first exposure to a virus results in the virus directly affecting the brain and spinal cord
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what is secondary encephalitis?
- virus first infects another part of the body, lies LATENT for a while
- and secondarily affects CNS when REACTIVATED
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What is the commonest cause of acute viral encephalitis?
herpes simplex virus
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which other viruses cause encephalitis and how are they transmitted?
- arbovirus: arthropod borne viruses transmitted by mosquitoes, ticks
- rabies virus: certain animal bites/saliva
-
when can you get secondary encephalitis in children?
after common childhood viral infections eg measles, mumps, rubella, chickpox or EBV
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what are the symptoms of most cases of encephalitis?
- headache
- irritability
- lethargy
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what happens in severe encephalitis?
- seizures
- N&V
- sudden fever
- altered levels of consciousness
-
what is the most common method of diagnosis for viral encephalitis?
CSF or blood nucleic acid - PCR
-
how do you confirm diagnosis of viral encephalitis?
viral culture and antigen detection
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on CT or MRI what does abscess look like?
encapsulated, well demarcated lesion
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what are the 4 sources of brain abscesses?
- 1. nasopharyngeal infection: otitis media, mastoiditis, sinusitis
- 2. blood stream
- 3. dental abscess (prev lung abscess)
- 4. direct to brain due to trauma eg fracture or surgery
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what are the most likely organisms of brain abscesses and why?
- reflect oro-nasopharyngeal flora
- aerobic G+ve cocci: strep milleri, staph aureus
- anaerobic G-ve: bacteroides, fusobacterium
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name 4 organisms that immunocompromised patients are likely to get causing a brain abscess
- protozoan parasite: toxoplasma gondii
- fungi: aspergillus, candida,
- norcardia
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what are 4 symptoms of brain abscesses?
- fever
- headaches
- focal seizures
- altered mental status
-
what 2 investigations are needed for diagnosis of brain abscess?
- image: MRI or CT
- diagnostic aspiration of the pus: microbiological smear and culture analysis
-
what is the empirical treatment of brain abscess?
- ceftriaxone and metronidazole
- or chloramphenicol if allergic to ceftriaxone or if pen resistant organism
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how do you treat staphylococcal brain abscesses?
chloramphenicol or linezolid
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