Infection and Immunity Flashcards
Why is an infant unlikely to have a common viral infection when less than 3 months of age?
Still has passive immunity from their mothers
What are the components of a septic screen?
Blood culture
FBC
CRP
Urine sample
If indicated :
CXR LP antigen screen on blood/CSF/urine meningococcal & pneumococcal PCR on blood/CSF PCR in viruses in CSF
What are some clinical features of neonatal sepsis?
Fever Poor Feeding Vomiting Apnoea Bradycardia Resp. Distress Jaundice Neutropenia shock seizures
IN MENINGITIS
bulging fontanelle
head retractionn
What are some risk factors for infection?
illness of family members
illness in the community
unimmunized
recent travel
contact with animals
immunodeficient
What are some secondary causes of immunodefiency?
autosplenectomy
nephrotic syndrome
primary immune deficiency
What are some red flag symptoms in an infected child?
if 3 months old, anything higher than 38C
3-6 months higher than 39
pale mottled blue
decreased level of consciousness
neck stiffness
bulging fontanelle
status epilepticus
resp. distress
bile stained vomiting
sever dehydration and shock
What is the immediate management of febrile child?
- Septic Screen
- Abx - > 3 months (cefotaxime, ceftriaxone
- 1 - 3 months (cefotaxime for septicaemia/meningitis)
(ampicilin for listeria)
(aciclovir if herpes simplex suspected)
- antipyretics
child shouldn’t be undressed
What are the potential causes of meningitis?
Viral - most common and self-resolving
Bacterial - may have sever consequences, 5-10% mortality and 10% of survivors have long-term neuro impairment
Malignancy
Autoimmune
What is the pathophysiology behind meningitis?
Damage and inflamm caused by host response to infection rather than organism itself
- endothelial damage leads to cerebral edema causing increased ICP
- inflamm response also causes vasculopath which leads to cerebral cortical infarct
- fibrin deposits blocks CSF resorption and leads to hydrocephalus
Most common organism causing meningitis in a 3 month old?
Group-B strep
Most common organism causing meningitis in above one month olds?
Neisseria meningitidis and Strep Penumoniae
How does meningitis present?
If child old enough to talk:
- Neck Stiffness
- Headache
- Photophobia
if younger than that symptoms are unspecific
If septicaemic - can present with tachycardia, tachpnoea, prolonged cap refill and hypotension
What assumption is made if a febrile child presents with purpura?
meningococcal sepsis
What is a positive Brudzinski sign?
flexion of neck when supine causing flexion of knees and hips
What a is a positive Kernig sign?
Hips and knees flexed in the supine position , then when knee is extended = back pain
What investigations would you carry out for suspected meningitis?
FBC, U&Es, LFC, CRP
blood culture, throat swab, stoll sample, urine sample
rapid antigen test (blood, CSF or urine)
PCR blood and CSF
LP
What are contra-indications for an LP?
cardio-resp instability
focal neuro signs
increased ICP
coagulopathy
thrombobytopenia
infection @ LP site
causes delay in abx start
What should be done to a febrile child who has a purpuric rash?
given IM benzylpenicillin and transferred urgently to hospital
What are cerebral complications associated with meningitis?
Hearing loss - damage to cochlear hair cells
Local Vasculitis - cranial nerve palsies
Local cerebral infarction - seizures could lead to epilepsy
Subdural effusion - assoc w H. infuenzae and pneumococcal meningitis
Hydrocephalus -
Cerebral Abscess - clinical condition deteriorates
What can be prophylactically for meningitis?
Rifampicin - not required if patient has been given third-gen cephalosporin
Household contacts who hgad group c meningococcal meningitis should be vaccinated with Men C vaccine
What is partially treated bacterial meningitis?
When children are treated with abx for non-specific febrile illness
This will cause cultures to show up negative and mask early meningitis
What is encephalitis?
inflammation of the brain matter when exposed to a virus or foreign protein
How does encephalitis present?
fever
altered consciousness
seizures
How would you differentiate encephalitis from meningitis?
Its hard to distinguish, therefore if in doubt treat both
Why should all children with encephalitis be treated with high-dose acyclovir?
while rare Herpes Simplex Virus can be very bad and have long-term consequences. Acyclovir can treat it
What organisms cause toxic shock syndrome?
Staph Aureus and group A strep which release toxins
How does Toxic Shock Syndrome present?
temperature above 39 degrees
hypotension
diffuse erythematous macular rash resemblibg sunburn palms and soles
mucositis
vomiting/diarrhoea
clotting abnormalities
altered consciousness
How would you manage toxic shock syndrome?
ICU support for shock
debride sites of infection
3rd gen cephalosporin
Clindamycin ( turns off toxin product)
IV immunoglobin
What is panton-valentine leukocidin producing S. aureus?
particularly bad form of s. aureus that can cause necrotising fasciitis and necrotising haemorrhaging pneumonia
How does a Meningococcal infection present?
Septicaemia and purpuric rash
with legions that are non-blanching, irregular size and a necrotic centre
What is management for any child that presents with a purpuric rash?
Treatment with systemic abx such as penicilllin
Which is the most dangerous strain of meningococcal infection?
B
as there is vaccination available for A and C
What are some complications/presentations of a staphylococcal and group a streptococcal infections?
impetigo
boils
periorbital cellulitis
scalded skin syndrome
How do human herpes viruses operate?
primary infection - latency established - long-term persistence in host in dormant state - certain stimuli might cause re-activation
