1 Flashcards
complications of meningitis
sensorrineural hearing loss (most common)
seizure
focal neurological deficit
infective: sepsis or intracerebral abscess
pressure: brain herniation, hydrocephalus
AB for under 3 months
IV cefotaxime + amoxicillin
AB for 3 months to 50 yrs
IV cefotaxime or ceftriaxone
AB over 50
IV cefotaxime or ceftriaxone + amoxicillin
AB meningococcal meningitis
IV benzyle penicillin or cefotaxime or ceftriaxone
AB pneumococcal meningitis
IV cefotaxime or ceftriaxone
AB haemophilus influenzae meningitis
IV cefotaxime or ceftriaxone
AB listeria meningitis
IV amoxicillin+ gentamycin
red light temp
over 38 in infant 0-3 months
amber light temp
tmep over 39 for 3-6 month
tachypnea
over 60 for 0-5 months
over 50 for 6-12 months
over 40 for over 1 year old
tachycardia
over 160 if pt under 1 year
over 150 if pt 1-2 years old
over 140 if pt 2-4 years old
cap refil
more than 3 seconds= dangerous
non blanching rash
send to ED, but give IM or IV benzyl penilcillin
how quickly to see pt
life threatning-999
red features but not life threatening= seen by paediatrician within 2 hours
amber: HCP discretion and can safety net
green: managed at home
safety net
seizure, develop non blanching rash, less well, fever more than 5 days, parent distressed.
Colour of skin traffic light
Green= normal
Amber= pallor
Red= pale, mottled, ashen, blue
Activity traffic light
Green; respond well to social ques, smile, stay awake, strong normal crying.
Amber= not responding to social cue, no smile, wake only to prolonged stimulation, dec activity
Red= no response to social cues, appears I’ll, not wake , weak or continuous cry
Traffic circulation
Green= normal skin and eyes, moist mucous membranes.
Amber= tachy cardia, CRT above 3, dry mucous membranes, poor feeding, reduced urine output
Red= reduced skin turgor
Most common cause of meningitis
Neisseria meningitidis; meningococcal
Strep pneumonias; pneumococcal
Haemofilus influenzae
Common features of meningitis, meningococcal disease, meningicococcal septicaemia
Fever, nausea and vomiting, head ache, non blanching rash, altered mental state and can also include lethargy, joint pain, muscle ache
Meningitis specific Exam
Photophobia
Kernig’s sign
Brudzinskis sign
Kernigs sign
Lie child on back, flex knee to right angle to body and completely extend leg at knee joint- cause stretching of meninges leading to pain which positive sign
Brudzinskis sign
Flex neck forward, child deletes hips and knees to avoid pain
Signs of septicaemia
Shock, hypotension, unusual skin colour, cold hands and feet, increased CRT
Suspected meningitis or meningococcal septicaemia in primary care
Transfer young pt with non blanching rash to hospital
with benzyl penicillin IV or IM
Primary care, no rash
Send to hospital but don’t give AB
How much benzyl penicillin do you give
300 mg if under 1 year old, or 600 for 1-9 years old
How would you investigate meningitis in hospital
Start ceftriaxone ASAP
Full set of bloods including clotting to test for coagulopathy
Blood cultures= N. Meningitits
Please= primary so do unless contraindications but don’t delay ABx,
What is contraindicated for LP
Raised, ICP, shock or hypovolaemia, neurological signs, unequal pupils or coagulation abnormalities
What do you look for in CSF
WBC, check total protein, glucose concentrations, gram staining, microbiology culture
Normal CSF
5-20 pressure, normal, 0.18-0.46 protein. 2.5-3.5 glucose, normal stain, less than 3 WCC
Bacterial CSf
Pressure over 30, turbid appearance, protein more than 1, glucose less than 2.2
Viral CSF
Normal or mildly increased pressure, clear appearance, less than 1 protein, normal glucose and normal gram stain. Monocytes.
Fungal or TB CSF
Fibrin web, less protein, less glucose, monocytes
SBAR
S- pt status, really unwell or stable (need to stabilise with ABC+ Resus)
B= pt details, age, condition, contraindications to GA, drug allergies, treatment received so far
A= recent obs, PEWS
R= anaesthetic review and assessment how to prepare for sedation and procedure
How do you prepare for operaiton
NBM for 6 hrs, water for 2
Pre op assessment
Consent
AMPLE
Allergies, medication (coagulation) , past history, last meal, events
Suspected meningitis and recent travel
Vancomycin and ceftriaxone/ cefotaxmine
Ca2+ containing infusion
Don’t use ceftriaxone use cefotaxime. Also don’t use ceftriaxone III premature babies, babies with jaundice, hypoalbuminuriaor acidosis
HiB meningitis
IV ceftriaxone for 10 days in total
S. Pneumonia meningitis
IV ceftriaxone for 14 days
Group B strep meningitis
IV cefotaxime for 14 days
L monocytogenes bacterial meningitis
IV amoxicillin of ampicillin for 21 days and gentamicin for at least first 7 days
Gram negative bacilli bacterial meningitis
IV cefotaxime for 21 days unless directed otherwise
Over 3 months unconfirmed uncomplicated suspected bacterial meningitis
IV ceftriaxone for 10 days
Under 3 months
Cefotaxime or amox for 14 days
Meningococcal
IV ceftriaxone for 7 days
What should you monitor
Hypoglycaemia, acidosis, hypokalaemia, hypocalcaemia, hypo afnesaemia, anaemia, coagulopathy
Assess for shock, raised ICP, dehydration using enteral fluid or feeds or IV isotonic fluids (NaCl 0.9% with glucose or dextrose 5% or 10% for neonates)
IV fluid resuscitation
Sign of shock= bonus of 20ml/kg NaCl 0.9% over 5-10 min via IV and then reassess
Shock persists
Second bonus of 20ml/kg of IV of NaCl0.9% or human albumin 4.5% solution over 5-10 min
Sign of shock after first 40ml/kg
3rd bolus, anaesthetic review, vasoactive treatment (adrenaline-NA?) . May need large fluid bolus
how else can you test for bacteria in CSF
GRAM STAIn, bacterial Ag
how else can you test for whihc virus in CSF
PCR
how else can you test for TB
Ziel Neelsen stain, flourecnesnce test, PCR
main cell type in CSF
b: neutrophil, V: lymphocyte
resp support for resp distress
15L face mask O2 via reservoir re breathing mask
threat to loss of airway patency or need assisted ventilation, hypoventilation, apoea
prepare for tracheal intubation, but prepare for sudden deterioration of pt - anticipate aspiration, pulmonary oedema, worsening shock, GCS under 9
feature of resp failure
irregular inspiration, hypoxia, decO2 saturation, hypercapnia
corticosteroids in pt under 3 months
DO NOT USE!
when to give dexmethasone for bacterial meningitis
ASAP if LP reveals: purulent CSF, WCC over 1,000, raised protein conc, bacteria on gram stain
max dose of dexmethasone given
0.15 mg/KG max dose 10mg QDS for 4 days straight
administer 1st dose within 4 hours of starting AB but don’t start dexmethasone more than 12 hours after starting ABx
meningococal septicaemia
DONT GIVE HIGH DOSE STEROIDS can give hydrocortisone 25mg/m2 QDS if pt unresponsive to vasoactive agents
what stain is N. meningitidis and does it have vaccine
gram negative, coffee bean shaped diplococci
MenB vaccine
what stain is strept pneumoniae and does it have vaccine
gram positive, mix of single cocci and chains. PCV13 vaccine
what stain is group B strep
gram posiitve, mix of single cocci and chains no vaccine
what protects N. menin.
polysaccharide capsule- coat bacteria and allow it to hide from phagocytes
factor H binding protein
super oxide dismutase to inactivate ROS
what protects strep pneumoniae
polysaccharide capsule
neuraminidase
IgA protease
pneumolysin (porin)- pore forming toxin which punch hole in immune cell and lyse cell
what protects group B strep
polysaccharide capsule
ScpB-C5a peptidase
IgA protease: degrades IgA
sod A
nuclease A degrade NETs
what is reverse vaccinology
genome based approach to identify vaccine candidates
antigens induce humoral AB located in extracellular or outer membrane region
Men B vaccine
Research through genome database and look for transcripts of proteins that are presented on surface of bacteria so presented out into extra cellular space (where IS interacts with them). In theory these can be used as antigens in humoral response.
Need to find a target which is important for bacteria so unable to down regulate it or hide it, without compromising their own survivability
We find 4 antigens that fit target and now made into multi component vaccine- mix different antigens together and different epitopes from antigens are combines with an attachment and adjuvant.
Group A stroptococcus infection pathway
GAS or s.pyogenes
asymptomatic carrier
non invasive infection
systemic comlications
immune sequelae
invasive infection
waht is non invasive infection of GAS
EG PHARYNGITIS OR STREP THROAT
systemic complications of GAS
scarlet fever where GAS produces streptococcal pyrogenic exotoxins A,B and C (SPE) which can induce inflammation
invasive infection in GAS
super antigens (strep pyrogenic exotocins) lead to super antigens so cause massive inflammation in host so direct systemic inflammation eg necrotiisng fascitis
immune sequelae GAS
M protein in pathogen similar to cardiac myosin so cause acute rheumatic fever
If unchecked, can result in immune sequelae where responses against toxins such as result in autoimmune responses resulting in rheumatic heart disease and glomerular nephritis.
necrotising fascitis
rapidly progressive infection that destroys deep soft tissues eg muscle fascia
M: surgical debridement of necrotic tissue and broad spec ABx (peniiclin)
pathology of necrotising fascitis H292
border of venule lumen, inside blood cells and tissues. bacteria surrounding it but neutrophils not able to get out and attack pathogen.
abnormal as 1st line defence= neutrophils but neutrophils unable to find pathogen and get into tissues
H292 hypothesis
molecule that interferes with neutrophil recruitment
so cell neutrophils unable to go and attack host due to H292 strain of GAS which results in fatality
neutrophil specific chemoattractant
CXCL8/IL8
C5a
how can you assay for levels of CXCL8
ELISA
western blot
CXCL8 degradation
Blood from invasive and throat from s. pyogenes outlets and measured rate of degradation of neutrophil attracting chemokine 68/ IL8 after incubating it with bacteria, degraded CXCL8 so suggests something in islets of invasive GAS which is degrading CXCL8
inactivation of CXCL8 (assessed by IL8 on ELISA) by blood isolates
Q. What molecules might H292 be producing?
A CXCL8-specific protease.
cleaved (cuts of C terminal 13 amino acid) then digested by H292- mass migration (stops this from happening?)
Q. How might we assess the effects of such a protease ?
SDS-PAGE analysis of CXCL8 digested with H292.
Mass spectrometry.
chemokine
40 soluble proteins
each binds to specific GPCR to elicit responses indluding chemotaxis, adhesion, release of anti microbial
cepA
gene encoding SpyCEP is upregulated in strains associated with necrotising disease
serine protease with homolgy to S8 proteases
catalytic triad
cell wall anchored by LPXTG motif
cepA -mine
cepA: can kill its own host and usually bacteria don’t want that as they loose their home. Mutation in regulatory part of the gene which lifts that expression.
Catalytic triad important for breaking apart substrate and chemokine. so the triad seen in very rare cases of necrotising GAS
what does SpyCep do molecularly
cleaves all ELR+ neutrophil recruiting chemokines (end terminal -ELR- important to recognise substrate) then proteases break down neutrophil recruiting chemokines
how do neutrophils usually work
migration (measured via live cell assay) measure neutrophile chemotaxis via chemokine gradient. recruit cells to CXCL8- very strong directional response
how does SpyCEP interfere with neutrophil function
SpyCEP has catalytic triad which digest the chemokines so fewer cells recruited and so less gradient so bacteria more likely to survive.
prove this with animal model that knocks in SpyCEP and see the impact of it
knock out SpyCEP - H575
necrotising strain in mice not kill them, because not on cell wall. SpyCEP knocked out, so not spread as much and not spread to lymph nodes so no fatality
SpyCEP knocked in-l.lactis
Knock in spycep gene- becomes deadly. Inject into thigh- allow bacteria to survive in tight and then spread to lymph nodes, liver and spleen
SpyCEP summary
Invasive strains of GAS produce SpyCEP.
SpyCEP selectively cleaves CXCL8, impairing neutrophil recruitment.
Knockout of cepA results in impaired GAS survival and spread to the regional lymph nodes.
Knock-in of cepA into L. lactis results in enhanced survival and rapid spread to organs.
AB and SpyCEP
AB available that recognises intact form of CXCL8 but none that recognise inactivated form.
CXCL8 incubated with bacterial lysate (so lyse cxcl8- inactive) and so then inject inactivated CXCL8 to mice, produce antibodies that complement inacitve CXCL8 and collect those AB.
then add the inactive cxcl8 with catalytic triad so that nocks out the enzymatic function wihhout losing structure (so makes competetive antagonist)
Km
the Michaelis Constant and is defined as the concentration of substrate at which a particular enzyme works at half its maximal velocity
compar strenght of enzyme substrate complexs
lowe KM means tight binding of substrate to enzyme
high KM: low affinity
K cat
number of substrate molecules processed per second.
Km of SpyCEP
Spycep very strong- only need small amount to be potent because CXCL9 is very strong
Different concentrations of CXCL8 degraded them with spycep over time, translate with mass spec, to work out Kcat
Km very low: as very high potency of CXCL8 (active even if tiny concentration), enzymes need to be sooo strong to cut all the CXCL8, so enzyme sooo potent
inhibitor of SpyCEP
Inhibitor 1: add to neutrophils, not reduce migration.
Spycep: add to neutrophils then reduces migration but then inhibitor 1 rescues that migration back so able to defeat pathogen
Spycep +inhibitor 1
infection of mice with l.lactic+ spycep knocked in
-spycep: ensures neutrophils don’t get rid of l. lactis so l.lactis can grow
-inhibitor 1: promotes local tissue clearance of SpyCEP bacteria
mice vaccination
Look at immunogenicity of recombinant spycep.
Took catalytically dead spycep (with catalytic traid shape but non functioning) and injected into mice to induce immune response and then measure anti spycep IgG took out antibodies from mice. So these antibodies stop CXCL8 from being cleaved by competitively antagonizing (so antibodies can now bined to spycep –as it was based on non functioning spycep- and stop it from working)
human vaccine
Best Epitope to be put in vaccine using crystallography and NMR to see which epitope are exposed on surface of vaccine on proteins and include them in vaccine
q
unclear how catalytic triad cooperate with each other
unclear how CXCL8 us bound and gets access to catalytic traid
need to generate structure which has CXCL8 bound to spycep
what awill be put in vaccine
deat mutants of spycep complexed with CXCL8
C5a
SCPA- c5a peptidase affect symptoms in beginning of infection. copy the techniques so both scpA and SpyCEP (CXCL8 peptidase- late stage or necrotising infections) in 1 vaccine
