Infections + immunity Flashcards
Meningitis pathology
Usually in first 5 years of life
Inflammation of leptomeninges surrounding brain tissue
Release of inflammatory mediators + activated leucocytes
Endothelial damage = causes cerebral oedema, raised ICP + decreased cerebral blood flow
Inflammatory response causes vasculopathy - causes cerebral cortical infarction
Fibrin deposits block reabsorption of CSF
Causes hydrocephalus
75% occur before age of 15
Incubation period for bacterial meningitis
2-10 days
Bacteria causing meningitis
Neonates = group B strep, E coli, Listeria
Infants + kids = Neisseria, strep pneumonia, Haemophilus influenza B
Adolescents = neisseria, strep pneumonia
S+S meningitis (+ for ages)
Shock = tachycardia, tachypnoea, prolonged cap refill General = fever, headache, photophobia, irritability, hypotonia, purpuric rash Infants = poor feeding, respiratory distress, coma Infants = lethargy, unsettled, refusing food Adolescents = muscle aches + pains, neck stiffness, N+V
Kernigs + Brudzinskis sign
Kernig = child lies supine, hips + knees flexed, back pain on extension of knee
Brudzinski’s = flexion of neck causes flexion of knees + hips
Complications of menigitis
Hearing loss Vasculitis Cerebral infarction = seizures Subdural effusion = especially H influenza Hydrocephalus Cerebral abscess
Investigations for meningitis
Lumber puncture Septic screen Bloods + glucose, lactate, cultures + gas Urine for M,C +S Nasal + throat swabs Viral/ bacterial PCRs
Management of bacterial meningitis
<3 months cefotaxime + amoxicillin Ceftrixone >3 months IM benpen in community Dexamethasone Rifampicin to family
S+S neonatal meningitis
Bulging fontanelle
Hyperextension of neck (opisthotonus)
Sepsis vs severe sepsis vs septic shock
Sepsis = infection + systemic inflammatory response Severe = sepsis + CV dysfunction/ acute respiratory distress Shock = Severe sepsis + CV dysfunction
Boundaries for tachycardia in children
<12 months = >160
12-24 months = >150
2-5 years = >140
Chicken pox incubation period + S+S
10-21 days (average 14)
Fever + itchy vesicular rash - mainly on trunk
Lasts 7 days
Complications of chicken pox
Secondary infection
Necrotising fasciitis
Encephalitis
VZV associated cerebellitis = ataxia + cerebellar signs = resolves within a month
Management of chicken pox
Fluids, paracetamol, calamine lotion
IV acyclovir if immunocompromised
Conjunctivitis organisms
Neonates = chemical (<24hrs), Neisseria gonorrhoea (<1 week), chlamydia (1-2 weeks)
Infants = H influenza, strep pneumoniae
School age = VZV, HSV, viral, allergic
S+S conjunctivitis
Purulent discharge (chlamydia + gonorrhoea) Blepharitis + dendritic ulcers (HSV) Red eye, discharge
Allergic vs chemical vs viral vs bacterial conjunctivitis symptoms
Allergic = itchy, swelling, watery discharge Chemical = neonatal Viral = sudden onset, pre-auricular lymphadenopathy, watery discharge Bacterial = purulent discharge
Management of conjunctivitis
Clean with saline
Neomycin
Gonococcal = cephalosporin
Chlamydia = erythromycin
Food allergy cause
IgE mediated
Infants = milk, egg, peanut
Older kids = peanuts, fish
S+S food allergies (IgE mediated vs not)
IgE mediated: facial swelling, anaphylaxis
Non IgE = D+V, abdo pain
Pathology of anaphylaxis
Maldistribution of fluid
Allergen reacts with IgE ab on mast cells + basophils (type 1 hypersensitivity reaction)
Causes capillary leakage, mucosal oedema + shock
Management of anaphylaxis
> 12 years = 500mcg IM adrenaline
6-12 = 300mcg
<6 = 150mcg
S+S infectious mononucleosis
Malaise Anorexia Low grade fever Tonsillitis/ pharyngitis Lymphadenopathy Spleno + hepatomegaly Maculopapular rash
Blood test results for infectious mononucleosis
Increased mononuclear cells
Atypical lymphocytes
Thrombocytopenia
Heterophile antibodies
Management of infectious mononucleosis
Supportive
DO NOT GIVE AMOXICILLIN
Pathology of Kawasaki’s disease
Systemic vasculitis
S+S of Kawasakis
Fever >5 days Non-purulent bilateral conjunctivitis Red mucous membranes Inflamed mouth, cracked lips Cervical lymphadenopathy Polymorphous rash Red palms + soles + peeling
Complications of Kawasakis
Coronary artery aneurysm leading to myocardial ischaemia
Management of Kawasakis
IV Immunoglobulin
Aspirin to reduce risk of thrombosis - continue until echo at 6 weeks shows no aneurysm
Measles incubation period + organism causing
7-12 days
Rubeola virus
S+S measles
Fever, cough, runny nose
Koplik spots, maculopapular rash
Rash starts behind ears on day 4 then spreads to face + trunk
Complications of measles + long term effects of this
Encephalitis - occurs about 8 days after onset
S+S = headache, convulsions
Long term effects: deafness, hemiplegia, learning difficulties
Pneumonia
Otitis media
Why is periorbital cellulitis a concern in children?
May be secondary to underlying bacterial sinusitis or due to spread from primary infection
What are complications of periorbital cellulitis?
Sub-periosteal abscess, cavernous sinus thrombosis, intracranial abscess
How to diagnose HIV in infants?
<18 mths = HIV DNA PCR
Over 18mths = detecting ab to virus
Incubation period for rubella
15-21 days
Pathology of rubella
RNA Rubella virus spread by droplet infection
Also called German measles
What are the complications of congenital rubella?
Malformations in cardiac, ocular, CNS + skeletal system
S+S of rubella
Headache, conjunctivitis, runny nose, maculopapular rash on face then spreading
Lymphadenopathy
Contraindications for LP
raised ICP,
thrombocytopaenia,
local infection at site of LP, extensive purpura
shock - stabilise first
after convulsions - stabilise first
respiratory insufficiency - stabilise first
CSF results for bacterial meningitis
Cloudy/ turbid
High protein (>1)
Low glucose
Neutrophils present
CSF results for viral meningitis
Clear fluid
Normal/ high protein
Normal glucose
Lymphocytes present
CSF results for TB meningitis
Clear/ slightly cloudy
High protein >1.5
Low glucose
Lymphocytes + acid-fast bacilli present
What infection is caused by herpes 4?
EBV
What antibodies are involved in HSP?
IgA + IgG interact + deposit in organs
What complication is associated with men B?
Febrile convulsions
Which vaccines are live?
MMR + BCG – avoid in immunocompromised kids
Describe the course of viral meningitis
starts with infection in mucus membrane, then lymph nodes, then causes initial viraemia then secondary viraemia (CNS infection)
What pathogens commonly cause viral meningitis?
entero, parechovirus, herpes (worst)
begin acyclovir for herpes one
What are the complications of meningitis + what measures are in place to detect these?
Septic shock, DIC, cerebral oedema, seizures
Long term: hearing loss, seizure, focal paralysis, cerebral palsy
All kids to have hearing test after 6 weeks from discharge
Which organism causing meningitis has the highest mortality?
Pneumococcal
What is the most common cause of meningococcal sepsis?
gram negative diplococci = Neisseria meningitis
What are the early S+S of sepsis?
leg pain, skin mottling, cold peripheries, breathing difficulties
Haemorrhagic rash = >12 hrs into illness
Late S+S of sepsis
Leaky vessels leads to poor perfusion so confusion, poor peripheral perfusion
Complications of sepsis (early + late)
Complications = DIC, AKI, adrenal haemorrhage, circulatory collapse
Late complications = deafness, renal failure, scarring, amputations
