Flashcards in Infection/immunology || Deck (76):
What is meningococcal disease/meningococcaemia?
Infections caused by Neisseria meningitidis
What 2 conditions do meningococcaemia cause?
1. Meningococcal meningitis
2. Meningococcal septicaemia
What are the 3 main causes of bacterial meningitis?
1. Streptococcus pneumoniae
2. Group B Streptococcus
3. Neisseria meningitidis
What age group do Neisseria meningitidis usually affect?
The age of over 1 month
What serotypes of Neisseria meningitidis are there (5)?
Group A, B, C, W, Y
What meningococcal vaccinations are there and what age are they given (3)?
MenC = 1 year
MenB = 2 months, 4 months, 1 year
MenACWY = 14 years
What is the pathophysiology of Neisseria meningitides?
Gram-negative bacterium found in the nasopharynx.
Lipopolysaccharide (LPS) is a component of the outer membrane of N. meningitidis which acts as an endotoxin and is responsible for septic shock and hemorrhage due to the destruction of red blood cells.
They produce an IgA protease, an enzyme that cleaves IgA class antibodies and thus allows the bacteria to evade a subclass of the humoral immune system
What is the mortality of bacterial meningitis?
What % of survivors of bacterial meningitis have long-term neurological impairment?
How does meningococcal meningitis present i.e. what are the 3 classical symptoms?
2. Neck stiffness
How does meningococcal meningitis present, other than the classical 3 symptoms (7)?
2. Poor feeding/vomiting
What does purpura in a febrile child indicate?
How should they be treated (2)?
Meningococcal sepsis - meningitis may or may not be present
1. Urgent admission
2. Immediately with iv penicillin or iv 3rd gen cephalosporin
What is a purpuric rash?
Red or purple discolored spots on the skin that do not blanch on applying pressure. Irregular in size and outline and may have a necrotic centre
What is the definition of a fever in a child?
How do you measure temperature in a child less than 4 weeks of age, and between 4 weeks to 5 years?
<4 weeks = electronic thermometer in axilla
4 weeks-5 years = Electronic or chemical dot thermometer in the axilla or infrared tympanic thermometer
In the assessment of how ill a child is, what red flags would you look for (6)?
1. Fever >38
2. Pale, mottled, cyanosed
3. Reduced consciousness, neck stiffness, bulging fontanelle, status epilepticus, focal neuro signs or seizures
4. Significant respiratory distress
5. Bile-stained vomiting
6. Severe dehydration or shock
What is the management of a febrile child that is not seriously ill?
Managed at home with a regular review by parents who have been given clear instructions
What is the management of a febrile child that are significantly unwell and have no focus of infection (6)?
1. Be in hospital
2. Investigations: Bloods, culture, swabs, LP, PCR etc
3. Septic screen
4. Parenteral Abx given immediately e.g. cefotaxime
5. Supportive care
6. Antipyretic agents e.g. paracetemol/ibrupofen
What are the investigations done for the work up of meningococcal sepsis and meningitis (5)?
1. Bloods: FBC, U+E, CRP, LFT
3. Blood culture
5. Throat swabs for bacterial culture and viral PCRs
What is the management of meningococcal sepsis and meningitis (2)?
1. Abx - Ceftriaxone
2. Supportive therapy
Do not delay
Is meningococcaemia a notifiable disease?
Can a septic child without a purpuric rash have meningococcaemia?
What are the possible complications of meningococcaemia (6)?
1. Hearing impairment
2. Local vasculitis
3. Local cerebral infarction
4. Subdural effusion
6. Cerebral abscess
What is sepsis?
When bacteria proliferate in the bloodstream, where the host response, which includes release of inflammatory cytokines and activation of endothelial cells
What are the common organisms that cause sepsis in neonates?
Early onset (2)
Late onset (1)
Early onset: Group B strep and E. coli
What are the common organisms that cause sepsis in infants and young children (5)?
1. Streptococcus pneumoniae
2. Neisseria meningitidis
3. S aureus and group A streptococci
4. Haemophilus influenzae type b
5. Bordetella pertussis
What are the red flag signs or symptoms of a febrile child on the NICE 'traffic light assessment' (8)?
1. Pale or mottled, or ashen or blue.
2. No response to social cues. Unable to rouse, or if roused does not stay awake.
3. Weak, high-pitched, or continuous cry.
4. Grunting. Tachypnoea (respiratory rate of 60 breaths per minute or more). Moderate or severe chest indrawing.
5. Reduced skin turgor.
6. Temperature of 38°C or higher in children 0–3 months of age.
7. Non-blanching rash. Bulging fontanelle. Neck stiffness.
8. Status epilepticus. Focal neurological signs. Focal seizures.
What are the amber flag signs or symptoms of a febrile child on the NICE 'traffic light assessment' (11)?
1. None of the red symptoms or signs.
2. Pallor reported by parent or carer.
3. Does not respond normally to social cues. Does not smile. Wakes only with prolonged stimulation. Decreased activity.
4. Nasal flaring. Tachypnoea (respiratory rate more than 50 breaths per minute in children aged 6–12 months, and more than 40 breaths per minute in children over 12 months of age). Oxygen saturation equal to or less than 95% in air. Crackles.
5. Poor feeding in infants.
6. Dry mucous membranes. Capillary refill time of 3 seconds or more. Reduced urine output (in infants ask about wet nappies).
More than 160 beats/minute under 1 year of age.
More than 150 beats/minute 1–2 years of age.
More than 140 beats/minute 2–5 years of age.
8. Temperature of 39°C or higher in children 3–6 months of age.
10. Fever for 5 days or more.
11. Swelling of a limb or joint. Not weight bearing or not using a limb
What is shock?
The circulation is inadequate to meet the metabolic demands of the tissues
What are the features of early shock (8)?
Normal bp maintained by:
3. Re-distribution of blood from venous reserve volume
4. Diversion of blood flow from nonessential tissues such as skin+peripheries
5. Delayed cap refill time
6. Sunken eyes and fontanelle
7. Decreased skin turgor
8. Decreased urinary output
What are the features of late shock (6)?
1. Falling bp as compensatory responses are failing
2. Acidosis (Kussmaul breathing)
4. Confusion/depressed cerebral state
5. Blue peripheries
6. Absent urine output
What Abx are given to community acquired sepsis in children up to the age of 17?
ceftriaxone 80 mg/kg once a day with a maximum dose of 4 g daily at any age
What Abx are given to neonates up to the age of 3 months for sepsis?
Ceftriaxone as well as ampicillin or amoxicillin which is active against Listeria
What is the immediate management of shock (7)?
2. Fluid resuscitation
If there is no improvement following fluid resus, PICU for:
3. tracheal intubation and mechanical ventilation
4. invasive monitoring of bp
5. ionotropic support
6. correction of haematological, biochemical and metabolic derangements
7. support for renal failure
What are common causes of sepsis in 'at risk' groups (3)?
1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Neisseria meningitidis
What is Kawasaki disease?
A systemic vasculitis
What is the main complication of Kawasaki disease?
What are the main CV signs (3)?
Aneurysms of the coronary arteries -> sudden death
Cardiovascular signs: gallop rhythm, myocarditis, pericarditis
What are the diagnostic criteria for Kawasaki disease?
Fever >5 days AND 4/5 of:
2. Mucous membrane changes e.g. red, dry, strawberry tongue
3. Cervical lymphadenopathy
4. Rash (polymorphous)
-red and oedematous palms and soles
-peeling of fingers and toes
How is Kawasaki disease diagnosed?
Based on clinical findings
What are some presenting features of Kawasaki disease (3)?
1. Young infants are miserable
2. High fever that is difficult to control
3. Inflammation of the BCG scar
What age does Kawasaki disease usually affect?
6 months - 4 years
What investigations can be done for Kawasaki disease (2)?
1. CRP, ESR, WCC = high inflammatory markers
2. Platelet count rises in 2nd week of the illness
What treatment is given for Kawasaki disease (4)?
1. Prompt treatment with iv immunoglobulins within first 10 days - reduces risk of aneurysms
2. Aspirin - reduce risk of thrombosis
3. Children with giant coronary artery aneurysms may require long-term warfarin therapy and close follow-up
4. Those with persistent inflammation and fever: Corticosteroids, infliximab or cyclosporin
Globally, how many children are affected by HIV?
Which country has the most children affected by HIV?
What is the estimated number of adolescents worldwide affected by HIV?
How many adolescents in UK are affected by HIV?
What are the short term risks of HIV?
A proportion of HIV-infected infants progress rapidly to symptomatic disease and onset of AIDs in the first year of life
Some remain asymptomatic for months/years
What does clinical presentation of HIV depend on?
The degree of immunocompromise
What are the possible presentations of children with mild immunocompromise (2)?
2. Parotid enlargement
What are the possible presentations of children with moderate immunocompromise (4)?
1. Recurrent bacterial infections
3. Chronic diarrhoea
4. Lymphocytic interstitial pneumonitis
What are the possible presentations of children with severe AIDs (4)?
1. Opportunistic infections: e.g. PCP
2. Severe growth faltering
4. Malignancy (rare)
More than one clinical feature is often present
What are the prevention measures of vertical transmission of HIV (5)?
1. Use of effective HRT during pregnancy
2. Postexposure prophylaxis given to infant after birth
3. Avoidance of breastfeeding
4. Active management of labour and delivery to avoid PROM
5. Prelabour C-section if mother's viral load is detectable
What is the treatment of HIV in children (5)?
1. Combination of 3-4 antiretroviral drugs
2. Prophylaxis against PCP with cotrimxazole
4. MDT management e.g. family clinic
5. Regular follow up
What is the pathophysiology of allergic disease?
Allergic diseases occur when individuals make an abnormal immune response to harmless environmental stimuli, usually proteins. The developing immune system must be 'sensitized' to an allergen before an allergic immune response develops.
The immune responses are classified as IgE mediated or non-IgE mediated. Most are IgE mediated.
What is the pathophysiology of IgE mediated allergic responses?
Early phase = within mins of exposure to allergen, caused by release of histamine and other mediators from mast cells. Causes urticarial, angioedema, sneezing etc
Late phase = occurs after 4-6 hours. Causes nasal congestion in the upper airway, and cough and bronchospasm in the lower airway
What are the common allergens for allergic disease (3)? What are their clinical presentations?
1. Inhalant allergens e.g. house dust mite, plant pollen - Red irritated eyes, constant sneezing, runny nose
2. Ingestant allergens e.g. cow's milk, nuts, soya - range of symptoms from urticarial to facial swelling to anaphylaxis usually 10 mins after food.
3. Insect stings/bites, drugs and latex - Pain, redness, swelling, itching, hives
What are the initial investigations of common allergies (2)?
1. History + examination
2. Referral to paediatric allergists - identify triggers to avoid
What is the management of common allergies (3)?
1. Specific allergen immunotherapy for treating allergic rhinitis and conjunctivitis, insect stings, anaphylaxis and asthma
2. Food allergies - Avoid relevant foods, antihistamines, adrenaline Epipen for severe reactions
3. Adrenaline Epipen for severe reactions
What are common drug allergies seen in children?
What tests can be done to support a diagnosis of a drug allergy (3)?
1. Allergy skin test
2. Allergy blood tests
3. Drug challenge -> may be the only way to conclusively confirm or refute the diagnosis
How do you report severe drug allergies?
On drug chart, there is a box for allergies
What is the immediate treatment of drug allergies (4)?
1. Antihistamines to relieve mild symptoms such as rash, hives, and itching
2. Bronchodilators for asthma-like symptoms
3. Corticosteroids applied to the skin, given by mouth, or given through a vein (intravenously)
4. im adrenaline for anaphylaxis
What is the causative agent of infectious mononucleosis?
How does infectious mononucleosis present in children (4)?
3. Severe tonsillitis/pharyngitis
4. Cervical lymphadenopathy
What is the treatment of infectious mononucleosis (5)?
What do you need to advise parents if children have infectious mononucleosis (2)?
Symptomatic as it is self-limiting
4. Corticosteroids - for airway compromise
5. Penicillin - for those with Group A Streptococcus on tonsils as well
1. May feel malaise for a few months after, but return back to normal activities when they can
2. Advise avoidance of contact sports to decrease the risk of splenic rupture
What are the complications of infectious mononucleosis (3)?
1. Splenomegaly and hepatomegaly
3. Airway obstruction
What are 2 the types of immunodeficiency in children? Which is more common?
Primary and Secondary (more common)
What are the causes of primary immunodeficiency (2)?
Genetically determined defect, usually:
2. Autosomal recessive disorders
What mneumonic describes the characteristics of infections that lead you to consider immunodeficiency?
What are the causes of secondary immunodeficiency (6)?
Caused by another disease or treatment
3. HIV infection
4. Immunosuppressive therapy
6. Nephrotic syndrome
What is the management of immunodeficiencies (6)?
1. Antimicrobial prophylaxis
-T cell and neutrophil defects:
cotrimoxazole to prevent PCP and itraconazole to prevent other fungal infections
-For B-cell defects:
Azithromycin to prevent recurrent bacterial infections
2. Abx for prompt treatment of infections
3. Screening for end-organ disease
4. Immunoglobulin replacement therapy
5. Bone marrow transplantation
6. Gene therapy
What are the clinical features of typhoid fever (8)?
1. Worsening fever
4. Abdo pain
8. 2nd week = constipation/diarrhoea
What is the treatment of typhoid fever (2)?
Cephalosporin or azithromycin
What are the clinical features of malaria (6)?
Onset occurs 7-10 days after inoculation:
2. Diarrhoea and vomiting
3. Flulike symptoms
What are the clinical features of cerebral malaria (6)?
1. Abnormal posturing
3. Conjugate gaze palsy (failure of the eyes to turn together in the same direction)
4. Opisthotonus (severe hyperextension of the body)