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
Which body parts do HSV 1 & 2 normally infect?
HSV1 - lip & skin
- gingivostomatitis
- cold sores
HSV2 - genitals
How does chicken pox present? A rough timeline of the symptoms?
fever
papules - vesicles - pustules - crusts
200-500 lesions on head and trunk which spread to peripheries
When is a chicken pox infection at its most infectious?
-2 to 6 days of illness
What complications can arise from a chicken pox infection?
secondary bacterial infection
encephalitis
purpura fulminans
if immunocompromised - progressive disseminated disease
What organism is responsible for chicken pox?
primary varicella zoster
What is shingles?
reactivation of latent varicella- zoster virus
vesicular eruption in dermatomal distribution of sensory nerves
In children which population are more likely to develop shingles?
Those who had a primary varicella-zoster virus infection in the first year of life
What conditions do Epstein - barr cause?
Glandular fever (infectious mononucleosis)
Burkitt lymphoma, lymphoproliferative disease and nasopharyngeal carcinoma
How does infectious mononucleosis present? how long do they last?
fever
malaise
tonsillopharyngitis
lymphadenopathy
also petechiea on soft palate, splenomegaly, hepatomegaly, maculopapular rash
jaundice
last for 1 -3 months
How would you diagnose infectious mononucleosis?
atypical lymphocytes
+ve monospot test
How do measles present?
cough throughout
conjunctivitis and coryza start to middle of infection
koplik’s spots (white spots on buccal mucosa) in middle of infection
rash towards the end
What complications associated with measles?
Encephalitis
Subacute sclerosing panencephalitis (SSPE)
- on average presents 7 years after infect
- can cause neuro dysfunction - dementia - death
What is most feared compication associated with mumps?
Orchitis - unusual in pre pubertal males
What is Kawasaki’s? Why is it’s diagnoses impt?
Systemic Vasculitis
can cause aneurysms of coronary arteries which can be potentially fatal
What age group and ethnicities are affected by Kawasaki’s?
6 months- 4 years
Japanese and afro-carribean
What are the diagnostic criteria for Kawasaki’s?
Fever lasting more than 5 days
4 of these 5 :
conjunctival infection
mucous membrane changes (red, dry cracked lips, strawberry tongue)
cervical lymphadenopathy
rash
extremities ( red oedematous palms + soles + peeling of fingers and toes
What is the treatment for Kawasaki’s?
IV immunoglobulin
aspirin to reduce the risk of thrombosis
antiplatelet aggregation
infliximab for persistent inflamm and fever
How would diagnoses of HIV be done in a child older than 18 months?
diagnosing antibodies to the virus
How would diagnoses of HIV be done in a child younger than 18 months?
transplacental maternal IgG HIV antibodies would confirm exposure not infection
HIV DNA PCR is most sensitive
- two negative HIV DNA PCRs within the first 3 months, after 2 weeks completing antiretroviral therapy = not infected
- confimed by loss of transplacental maternal HIV antibodies
How would HIV present?
Some symptomatic in the first year
Others asymptomatic till later in life
If mild - lymphadenopathy, parotitis
moderate - recurrent bacterial infections, candidiasis, chronic diarrhoea and lymphotic interstitial pneumotitis
What is treatment for HIV?
infants - starts antiretroviral
in older - prophylaxis against organisms with - co-trimoxazole
immunise except for BCG
What immunisations are given to newborns?
Only in high-risk infants - BCG jab is given
What does the 5-in-1 jab consist of? when is it given?
diptheria, tetanus, pertussis, h. influenzae b and polio
2,3 and 4 months
What is the PCV13 vaccine? When is it given?
pneumococcal conjugate vaccine
2, 4 and 13 months
When is the rotavirus vaccine given? what route?
2 and 3 months
orally
What jabs are given between 12 and 13 months?
booster Hib, Men C and MMR
How would immunune deficiencies present?
recurrent bacterial infections
sever infections such as meningitis, osteomyelitis and pneumonia
infections usually severe
severe long-lasting warts
extensive candidiasis
abscesses of internal organs
What organism is responsible for scalded skin syndrome?
localised staphylococcal infection
What are the clinical features of scalded skin syndrome?
fever, irritability then redness of skin
formation of blisters 24-48 hrs after
top layer of skin begins to peel of - Nikolsky sign
How would you treat scalded skin syndrome?
IV flucloxacillin
What organism responsible for Slapped-Cheek?
parvovirus B19
How does slapped-cheek present?
mild feverish illness
rose-red rash which makes cheeks red (doesn’t involve palms and soles)
Child feels better as rash appears
What is treatment for slapped cheek?
normally none needed
What is peculiar about the rash in slapped cheek?
Can be triggered months after infection
by heat, warm bath, sunlight
What organism responsible for Scarlet fever?
Group A haemolytic strep
How does scarlet fever present?
incubation period of 2-4 days
fever
malaise, headache, nausea/vomiting
sore throat
strawberry tongue
fine pin head rash on torso and more obvious on flexures
‘sandpaper’
desquamation around fingers and toes in late disease
How would you diagnose scarlet fever and treat?
throat swab
oral penicillin V for 10 days
What complications can arise from scarlet fever?
otitis media
rheumatic fever
acute glomerulonephritis
What organism responsible for hand, foot and mouth?
Coxsackie A16
How does hand, foot and mouth present?
mild fever and sore throat
oral ulcers
vesicles on palms and soles
What form of TB is more common in children?
Paubacillary, TB more likely to progress from TB infection to TB disease in children and infants
*in adults its more likely to be TB INFECTION
How would asymptomatic TB present?
50% of infants and 90% of older children will show minimal signs and symptoms of infection
disease will remain latent and develop into active disease later in time
Matoux test may be positive > initiaite treatment
How would symptomatic TB present?
fever
anorexia and weight loss
cough
local enlargement of peribronchial lymph nodes
pleural effusions
Where can a extra-pulmonary TB infection manifest?
central nervous system (tuberculous meningitis - the most serious complication)
vertebral bodies (Pott’s disease)
cervical lymph nodes (scrofuloderma)
renal
gastrointestinal tract
How would you diagnose TB in children?
NG tube to get gastric aspirate
Mantoux test - >10mm, >15mm with BCG
interferon-gamma release assays (IGRA)
CXR - hilar lymphadenopathy (can be mistaken for lymphoid interstitial pneumonitis)
What from patients history should be taken into account when doing Mantoux test?
BCG vaccination
Disadvatage of Mantoux test?
can’t reliably distinguish between TB infection and TB disease
will be non-responsive if patient has HIV (immunocompromised)
How would you treat TB?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Rifampicin and Isoniazid after 2 months
- in tuberculous meningitis give dexa for first month atleast
- if Mantoux positive but asymp > rifampicin and isoniazid for 3 months
What does
High IgG + high IgM mean?
recent infection
What does High IgG + normal IgM mean?
previous infection or vaccination
What does Normal IgG + normal IgM mean?
no previous exposure
