Infections and Immunity Flashcards
What immunisations are given <1yr? (8)
8 weeks (2 months):
1) 6-in-1 vaccine
2) Pneumococcal (PCV) vaccine
3) Rotavirus vaccine
4) MenB
12 weeks (3 months):
5) 6-in-1 vaccine - 2nd dose
6) Rotavirus vaccine - 2nd dose
16 weeks (4 months):
7) 6-in-1 vaccine - 3rd dose
8) PCV - 2nd dose
9) MenB - 2nd dose
What immunisations are given aged 1-15yr? (10)
1 year:
1) Hib/MenC - 1st dose
2) MMR - 1st dose
3) PCV - 3rd dose
4) MenB - 3rd dose
2-10yrs:
5) Flu vaccine - every year
3yrs and 4 months:
6) MMR - 2nd dose
7) 4-in-1 pre-school booster
12-13yr:
8) HPV vaccine
14yr:
9) 3-in-1 teenage booster
10) MenACWY
What immunisations are given to adults? (3)
65yr:
1) Pneumococcal (PPV) vaccine
2) Flu vaccine (and every year after)
70yr:
3) Shingles vaccine
What immunisations are offered to pregnant women? (2)
Flu vaccine - during flu season Whooping cough (pertussis) vaccine - from 16 wks
What is in the 6-in-1 vaccine?
DHHPTW
1) Diptheria
2) Hep B
3) Hib - Haemophilus influenza type b
4) Polio
5) Tetanus
6) Whooping cough - pertussis
What is in the 4-in-1 pre-school booster?
DTPP
1) Diphtheria
2) Tetanus
3) Whooping cough - pertussis
4) Polio
What is in the 3-in-1 teenage booster?
DTP
1) Diphtheria
2) Tetanus
3) Polio
Which vaccines are live? (3)
1) Influenza
2) MMR
3) Rotavirus (oral)
+ BCG
When does meningitis mostly occur in children?
Mostly in first 5 years of life
75% of cases are <15yrs
Younger children are at greater risk of brain damage and are more difficult to diagnose
How does bacterial infection of the meninges occur, and why is this more likely to occur in children?
Colonisation of nasopharyngeal epithelium
Invasion of blood then meninges - BBB is less developed in children so these bugs are more likely to reach the meninges and cause infection
Cerebral oedema caused by inflammation + leaky vessels
What is the pathophysiology of viral meningitis?
Infection of a mucus membrane followed by lymph node involvement
Primary viraemia = causes viral illness
Secondary viraemia = involved organs such as liver
What are some risk factors for neonatal meningitis? (6)
1) Low birth weight (<2500g)
2) Prematurity
3) Premature rupture of membranes
4) Traumatic delivery
5) Fetal hypoxia
6) Maternal peripartum infection
What are the most common bacterial causative organisms of meningitis in neonates? (3)
1) Group B strep
2) E coli
3) Listeria monocytogenes
+ other coliforms
What are the most common bacterial causative organisms of meningitis in infants (1 month to 2 years) (4)
Streptococcus pneumoniae
Neisseria meningitides
Haemophilus Influenza B
Meningococcus C
**The last 2 are both now vaccinated against and so their incidence has dropped
What are the most common causative organisms of meningitis in adolescents / adults? (3)
1) Neisseria meningitidis
2) Streptococcus pneumoniae
3) Listeria monocytogenes
What symptoms may meningitis present with? (13)
Photophobia, neck stiffness and headache are the classical distinguishing symptoms but the young child (infant) might not have these making diagnosis more difficult
Infants may have non-specific signs of infection
- High-pitched cry
- Bulging fontanelle
- Poor feeding
- Respiratory distress
Other meningitic signs
- Irritable
- Vomitting
- Drowsiness
- Seizures
What are some signs of raised ICP? (6)
1) Papilloedema
2) Altered / LOC
3) Bulging fontanelle in neonates
4) Increased BP
5) Decreased HR
6) Irregular respirations
7) Focal neurological signs
What is meningitis vs meningococcal septicaemia?
Meningitis = inflammation of the leptomeninges that surround the brain and spinal cord
- Various causative organisms
- May have neck stiffness / photophobia
- Unlikely to have a rash
Meningococcal septicaemia = systemic infection
- CAUSED BY NEISSERIA MENINGITIDIS
- Rapidly spreading purpuric rash
- May or may not also have meningitis
- Often fatal
What signs of meningism can be found on examination
1) Kernig’s sign - unable to extend knee when thigh flexed to 90 degrees
2) Brudunski’s sign - involuntary lifting of leg when lying supine and head is raised
What investigations are done in meningitis? (6)
Do not delay abx by more than 30 mins
1) Bloods - FBC, U&Es, CRP, glucose, blood cultures, gases
2) CT head
3) LP unless contraindicated
4) Urine for MC+S
5) Nasal / throat swabs
6) CXR - lung abscess
What would the LP results be in bacterial vs viral meningitis?
Viral:
- Clear / hazy appearance
- Lymphocytes +
- Protein +
- Glucose = Normal
Bacterial:
- Cloudy / purprulent
- Neutrophils ++
- Protein ++
- Glucose = Low
List some contraindications to LP (7)
1) Raised ICP = stabilise first
2) Shock = stabilise first
3) After convulsions = stabilise first
4) Respiratory insufficiency = stabilise frist
5) Abnormal clotting
6) Infection at LP site
7) Extensive purpura
What is a pyrexia?
What is a red flag?
What is an amber flag?
Temp of 38 degrees celsius or more
Infants <3 months, fever of more than 38 = red flag
Infants 3-6 months, fever of over 39 = amber flag
What is the treatment of suspected meningococcal meningitis in the community?
If in doubt - treat as bacterial
IM benzylpenicillin single dose
<10yr = 1g 1-9yr = 600mg <1yr = 300mg
What is the treatment of suspected bacterial meningitis in hospital?
<3 months = IV cefotaxime + amoxicillin/ampicillin to cover listeria
> 3 months = IV ceftriaxone
+ dexamethasone to reduce neurological sequelae
Symptomatic treatment - antipyretics, analgesics, IV fluids
Inform PHE - they offer ciprofloxacin to all close contacts
Which bacterium and which virus cause the highest morbidity/mortality in meningitis?
Streptococcus pneumoniae
HSV
What are some complications of meningitis?
Immediate:
- Septic shock
- Seizures
- DIC
- Cerebral oedema
- Hydrocephalus (blockage of ventricular outlet)
Delayed:
- Hearing loss (follow up includes hearing test)
- Epilepsy
- Cerebral palsy (if <2yr)
What vaccinations are given as prevention for meningitis and when are they given?
Men B vaccine is given at 2, 4 and 12-13 months
Meningitis ACWY given at 13-18 years old
What type of bacteria is Neisseria meningitides?
Gram -ve diplococci
What groups are there of Neisseria meningitides?
A, B, C, W, Y
What are the early signs of meningococcal septicaemia? (6)
1) Fever
2) Mottling
3) Leg pain
4) Cold peripheries
5) Breathing difficulties
6) Non-blanching rash >12hrs
What are some early complications of meningococcal septicaemia? (4)
1) DIC
2) AKI
3) Adrenal haemorrhage
4) Circulatory collapse
How should non-blanching rash lesions be referred to depending on their size?
<3mm = petechial 3-10mm = purpura >10mm = ecchymosis
What is the classic surgical sieve pneumonic
VITAMIN CDE
Vascular Infective / Inflammatory Trauma Autoimmune Metabolic Iatrogenic Neoplastic Congenital / Coagulopathy Developmental / Digestive Endocrine / Environment
What is a vascular condition causing purpura?
Henoch-Schonlein purpura
What is the distribution of purpura in Henoch-Schonlein purpura?
What is the platelet count?
Pupura distributed across extensor surfaces, buttocks and ankles
Normal platelet count
What is an infective / inflammatory cause of purpura?
Meningococcal disease
What is the distribution of purpura in meningococcal disease?
Diffuse macular rash - appear before your eyes
Give immediate IM Benzylpenicillin !!!!
What coagulopathies can cause purpura?
Thrombocytopenia
DIC
Scurvy (vit C deficiency causes weak capillary walls)
What is the course of purpura in thrombocytopenia?
Petechial rash followed by a purpuric rash
Usually acute onset in the weeks following a URTI
What is Henoch-Schonlein purpura? What are it’s main features?
IgA-mediated, autoimmune hypersensitivity vasculitis of childhood
Main features:
- Purpura
- Arthritis
- Abdominal pain
- GI bleeding
- Glomerulonephritis
Define:
1) Sepsis
2) Septicaemia
3) Septic shock
Sepsis = systemic inflammatory response + source of infection
Septicaemia = blood borne infection which causes sepsis
Septic shock = severe sepsis causing hypotension and compromised tissue perfusion
Describe the process of septic shock
Bacterial toxins cause systemic inflammatory response:
1) Vasodilation
2) Increased microvascular permeability
3) Tissue hypoxia
4) Myocardial depression
5) DIC
How may early signs of compensated shock present?
Tachycardia Cool peripheries Tachypnoea Decreased urine output Inc cap refill time O2 sats <95% Confusion / LOC Hypotension (later)
NB high fever can also cause tachycardia and peripheral vasoconstriction which may present similarly to early compensated shock
If septicaemia is meningococcal = look for signs of meningitis and non-blanching petechial/purpuric rash as an early sign (not always present) - in 30% rash is blanching and maculopapular
What is involved in a septic screen in children?
Septic screen = CRAP blood
Cultures - blood, urine, stool, CSF (if no raised ICP), indwelling catheters
Radiography - CXR, AXR
ABG - metabolic acidosis
Pee (urinalysis)
Bloods - FCB (raised WCC), U&Es, LFTs, CRP, ESR, glucose, calcium, phosphate, clotting
Which vaccine commonly gives a fever in the days following its administration?
MMR
Parents often bring children to A&E but advise them this is a self-limiting reaction
List some ddx for a child presenting with a fever and a rash (7)
1) Measles
2) Rubella
3) Roseola
4) Scarlett fever
5) Fifth disease
6) Hand food and mouth disease
7) Chicken pox
8) Meningococcaemia
List some ddx for a febrile child with a swelling in the neck (5)
1) Cervical adenitis
2) Infectious mononucleosis (EBV)
3) Mumps
4) Thyroiditis (often no fever)
5) Mastoiditis
List some ddx of a child with pyrexia of unknown origin (6)
1) Infective endocarditis
2) Osteomyelitis
3) Collagen vascular disease
4) IBD
5) Neoplastic disease
6) Factitious fever
List some ddx of a febrile child with recurrent infections (2)
1) HIV / AIDS
2) Hyposplenism / splenectomy
What virus causes chickenpox?
Varicella-Zoster virus (HHV-3)
What does reactivation of VZV lead to?
Shingles
What is the incubation period of chicken pox?
10-21 days
What is the usual duration of the rash in chickenpox?
6-10 days
What is the recommended isolation period for chicken pox?
Until all the lesions are crusted over (usually 5-6 days)
Describe the type of rash and distribution in chickenpox
Vesicular rash
Occurs in crops starting on trunk and spreading to face and extremities
Erythematous macules -> papules -> vesicles filled with clear fluid on erythematous base -> eruption of vesicles -> crusted papules -> hypopigmentation of healed lesions
Can have multiple stages on body at once
What is the first feature of chickenpox? How long does this last?
Pyrexia and malaise for 1-2 days prior to onset of lesions
How else does chickenpox present?
Headache Malaise Abdo Pain Itchy rash Shallow ulcers of the mucous membranes Coryzal
What may occur when immunocompromised get chickenpox?
Pneumonia
Large and bleeding vesicles
DIC
What investigations are done for chickenpox?
Diagnosis clinical
PCR of vesicle fluid - confirms diagnosis
What is the management of chickenpox in an otherwise healthy individual?
- Advise re fluid intake, avoid scratching and keep nails short, avoid contact with pregnant women/neonates/immunocompromised
- Use paracetamol for analgesia and pyrexia
- Antihistamines and emollients for pruritis
Why are NSAIDs not advised for chickenpox?
Possible association with necrotising soft tissue infections
What populations require antiviral treatment for chickenpox?
IV aciclovir:
- Immunocompromised
- Systemic disease
- Pt on high dose steroids
- New lesions appearing after 8 days
PO aciclovir:
- >12yr
What are some complications of chickenpox?
1) Secondary infection of skin lesions (e.g. Group A strep (step pyogenes) can produce necrotising fasciitis and toxic shock syndrome)
2) Viral pneumonia
3) Encephalitis
4) CNS complications e.g. benign cerebellar ataxia
Why is chickenpox late in pregnancy concerning?
It can cause premature delivery
If rash appears within a week of delivery or 2 days after, there is a risk of neonatal chickenpox
Why is neonatal chickenpox concerning?
There is transplacental transmission of virus but not antibody, and there is no time for IgG to develop and the baby is at 30% risk of death from severe pneumonia or fulminant hepatitis
NB IgG can cross the placenta (initial IgM cannot) - so if at least a week passes between rash and delivery is fine as IgG will have developed
Why is chickenpox within first 2 weeks of pregnancy concerning?
Risk of congenital varicella syndrome
- IUGR
- Microcephaly
- Cortical atrophy
- Limb hypoplasia
What is the treatment of neonatal chickenpox?
Immunoglobulin and aciclovir
How is chickenpox transmitted?
Respiratory droplets or direct contact with vesicular fluid
When should parents be advised they can reenter their children to school with chickenpox?
6 days after the last spots appear
Why is ceftriaxone contraindicated in babies < 3 months?
It displaces bilirubin from albumin binding sites, resulting in higher levels of bilirubin that accumulate in the tissues
