Paeds Immunology and Infectious Disease Flashcards
When does post vaccination fever start and end?
Begins within 24hrs of shot
Lasts 2-3 days
Usually mild fevers
How high is too high for a fever related to teething?
Fevers related to teething should not exceed 38.5C
If higher than this suspect another source
What is the most common cause of serious bacterial infection (SBI) without an obvious cause?
Urinary tract infections (UTI)
Peaks in 2nd yr of life for girls (8.1%)
Uncircumcised boys much higher rate than circumcised in 1st year of life, then both drop off
What is the rate of occult bacteraemia and what are the usual causes?
Used to be 10% but now <0.5%, largely due to HiB and pneumococcal vaccines
Thus unvaccinated and pre-vaccinated children have much higher rates
Other causes although rare include Salmonella species, E.coli and Meningococcus
What is the most common cause of occult bacteraemia (OB) in age group 3months to 5yrs?
Strep pneumoniae
Although with the advent of vaccines it rarely causes serious invasive infections (<5%)
Independent of vaccination status, which risk factors increase the rate of OB becoming an SBI?
Indigenous status
Nephrotic syndrome
Asplenia
Active cancer (+/- on chemo)
Intracranial shunt
Cochlear implant
Immunosuppresive therapy
HIV/AIDS/congenital immune deficiency
Which is the highest risk age groups for bacterial meningitis?
90% of bacterial meningitis occurs in children <5yo
Neonates have the highest mortality rate of 20%
1/3rd of children will have ongoing neurological sequelae post infection
What are the most common organisms causing meningitis in children <3mo?
Listeria monocytogenes
E.coli/Klebsiella/enterobacter
Group B strep
Usually acquired by vertical transmission from the mother
What are the most common organisms causing meningitis in children >3mo?
Neisseria meningitides
Strep pneumoniae
Previously H. influenzae prior to vaccination (much higher risk in unvaccinated)
Usually acquired by encapsulated strains entering the bloodstream and crossing the BBB, thus asplenia is a significant risk factor
What are the most common causes of viral meningitis?
Coxsackie virus
Enterovirus
Paraechovirus
HSV meningitis is uncommon and usually recovers well, but if becomes HSV encephalitis has very poor outcomes
What are the risk factors for meningitis in a febrile child?
Recent neurosurgical procedure
VP shunt or cochlear implant
Immunocompromised (consider cryptococci and mycobacteria)
Maternal GBS in <3mo
Contact with patients with enterovirus, HSV cold sore or meningitis
Overseas travel
How does giving antibiotics first alter the findings of an LP in meningitis?
Does not alter the cell count, protein levels or glucose levels
PCR for pneumo/meningococcus still highly sensitive and specific
Much lower likelihood of culturing the bacteria (although only 70-80% chance in those without antibiotics)
What are the normal values for paediatric CSF?
In a traumatic tap the RBC’s should be disregarded and the WCC’s treated as normal, if they are high then treat
When should dexamethasone be considered in meningitis and what is the evidence?
0.15mg/kg QID IV for any cases in children over 3mo
No evidence for or against <3mo
Older than 3mo shown to reduce rates of hearing loss
Poor evidence if partially treated (ie on amoxicillin for URTI)
What are the TORCH infections?
Toxoplasmosis
Other (Syphilis, VZV)
Rubella
CMV
Herpes Simplex Virus
In utero infections leading to severe downstream complications
Who gets idiopathic facial cellulitis?
Usually in children aged 0-5yrs
It can be caused by bacteraemia and blood cultures are often indicated
What are the indications for antibiotics in otitis media?
- Systemically unwell
- <6months old
- ATSI
- Immunocompromised
- Affecting the only hearing ear
- Cochlear implant on that side
- Likely suppurative complication (ie mastoiditis etc)
What are the signs of mastoiditis?
Protruding auricle
Posterior auricular swelling and erythema
External auditory canal oedema
What is the treatment for mastoiditis?
Urgent paeds ENT referral
Fast
analgesia
50mg/kg of Flucloxacillin + 50mkg/kg of ceftriaxone/cefotaxime
What are the Major Jones criteria for Acute Rheumatic Fever?
Arthritis
- Poly low risk, mono high risk
Carditis/Valvulitis
Sydenhams Chorea
- CNS involvement
Subcutaneous nodules
Erythema marginatum
What are the minor Jones criteria for Acute Rheumatic Fever
Arthralgia
- Poly low risk, mono high risk
- Only used if arthritis absent
Fever >38.5C
Prolonged PR interval
- Only used if Carditis absent
- prolongation varies with age from 110 neonate to 200 in late teens
Elevated inflammatory markers
- CRP >30
- ESR >60 low risk and >30 high risk
How is the diagnosis of acute rheumatic fever made
Must have recent suspected GAS infection
+
Child meets 2 major criteria
Or
1 Major and 2 minor criteria
What is a mnemonic for the major jones criteria?
JONES
J- Joints ie arthritis
O- pericardial effusion makes heart shaped like an O
N- subcutaneous Nodules
E- erythema marginatum
S- Sydenhams chorea
What are the antibiotics given for suspected meningoencephalitis in different age groups?
<2 months
- Cefotaxime 50mg/kg and Benzylpenicillin 60m/kg
> 2months
- Ceftriaxone 50mg/kg +/- Vancomycin 15mg/kg if MRSA suspected/confirmed
Consider Aciclovir 20mg/kg if suspected viral cause (ie HSV)
