Infectious Disease Flashcards
What is otitis media?
Rapid onset of S+S of ear infection
Inflammation in the middle ear
Associated with an effusion
From NICE CKS
Causes of acute otitis media?
what are the common pathogens?
Bacterial:
* Haemophilus influenzae
* Moraxella catarrhalis
* Streptococcus pyogenes
* Streptococcus pneumoniae - less of this now since pnuemococcal vaccine
Viral:
* RSV - respiratory syncytial virus
* rhinovirus
* adenovirus
* influenza virus
* parainfluenza virus
What are RF for acute otitis media?
(for children in particular)
- Young age.
- Male sex.
- Frequent contact with other children such as daycare or nursery attendance or having siblings (increases exposure to viral illnesses).
- Formula feeding — breastfeeding has a protective effect.
- Craniofacial abnormalities (such as cleft palate).
- Use of a dummy.
- Prolonged bottle feeding in the supine position.
- Family history of otitis media.
- Lack of pneumococcal vaccination.
- Gastro-oesophageal reflux.
- Prematurity.
- Recurrent upper respiratory tract infection.
- Immunodeficiency
from NICE CKS
What are RF for acute otitis media?
(for children in particular)
- Young age.
- Male sex.
- Frequent contact with other children such as daycare or nursery attendance or having siblings (increases exposure to viral illnesses).
- Formula feeding — breastfeeding has a protective effect.
- Craniofacial abnormalities (such as cleft palate).
- Use of a dummy.
- Prolonged bottle feeding in the supine position.
- Family history of otitis media.
- Lack of pneumococcal vaccination.
- Gastro-oesophageal reflux.
- Prematurity.
- Recurrent upper respiratory tract infection.
- Immunodeficiency
from NICE CKS
What are complications of acute otitis media?
- Persistent otitis media with effusion.
- Recurrence of infection.
- Hearing loss (usually conductive and temporary).
- Tympanic membrane perforation.
- Labyrinthitis.
- Rarely, mastoiditis, meningitis, intracranial abscess, sinus thrombosis, and facial nerve paralysis.
How does acute otitis media present?
Presentation Hx and examination findings
Older children:
* earache
* reduced hearing in affected ear
* balance issues and vertigo if affected vestibular system
Younger children
* holding, tugging or rubbing ear
* fever
* crying
* poor feeding
* restlessness
* behavioural changes
* cough
* rhinorrhoea
* reduced hearing in affected ear
On examination:
* distinctly red, yellow or cloudy TM
* bulging of the TM, has loss of landmarks and air-fluid level behind the TM
* Perforation of the TM and/or discharge in external canal
* reduced hearing in affected ear.
nice cks
Why is Dx of otitis media difficult in children younger than 6m?
from nice cks
- may have coexisting systemic illness - e.g. bronchiolitis
- symptoms are more non-specific when younger
- TM is not as visible in child as ear canal is small and tends to collapse
DDx for acute otitis media?
If PC is middle ear inflam or efffusion:
* OM with effusion aka glue ear
* chronic suppurative OM
* Myringitis
If PC is just earache
* Otitis externa
How is acute otitis media managed?
When need to admit?
treatment options in community?
Admit if:
* younger than 3m
* 3-6m with temp of 39+
* severe systemic infection (remember we have a low threshold for sepsis in children)
* present with complications of AOM.
In community:
* Analgesia - NSAIDs, paracetamol. Can be provided as an ear drop analgesia
* If think abx are needed = 5-7 day course amoxicillin. / clarithromycin or erythromycin. Co-amoxiclav can also be used if no response to these.
How is recurrent AOM managed?
Urgent referal (2weeks) to ENT specialist
- especiallly if they have Hx of cleft palate or Down’s syndrome
- have nosebleeds too
- have lymphadenopathy
If they don’t have these features:
* avoid exposure to passive smoking, dummies, flat supine feeding
* ensure they have had pnuemococcal vaccine
* ensure GORD is managed (as can present together)
What is tonsillitis?
Inflamation of the tonsils.
Can occur in isolation or as part of a generalised pharyngitis
What are common organisms causing tonsillitis?
Viral causes:
* Rhinovirus
* Coronavirus
* Parainfluenza virus
* Influenza type A and B
* Adenovirus
* HSV1
* EBV
Bacterial causes:
* Group A Streptococcal infection - Streptococcus pyogenes.
* Group C and G Beta-haemolytic streptococci. = Streptococcus pneumoniae
* Haemophilus influenzae
* Moraxella catarrhalis
* Staphylococcus aureus
- What is Waldeyer’s Tonsillar Ring?
- Why is it relevant in tonsillitis?
- A ring of lymphoid tissue made up of the adenoids, tubal tonsils, palatine tonsils and lingual tonsil.
- These get infected and enlarged in tonsilitis - the palatine tonsils are most commonly infected
How does acute tonsillitis present?
Hx and Ex
- Sore throat
- Fever (above 38C)
- Pain on swallowing
O/E:
* red, inflamed and enlarged tonsils
* can have exudate on = white pus on tonsil
* anterior cervical lymphadenopathy (in anterior triangle of neck)
What 2 criteria can be used to estimate probability that tonsillitis is due to a bacterial cause, and requires abx?
Describe each.
- Centor criteria - score of 3 or more = bacterial tonsilitis
* Fever over 38C
* Tonsillar exudate
* Absence of cough
* Tender anterior cervical lymph nodes (lymphadenopathy) - FeverPAIN Score - score of 4 or 5 = bacterial tonsillitis
* Fever above 38C
* Purulence (exudate)
* Attended rapidly (within 3 days)
* Inflamed tonsils (severe)
* No cough or coryza
You should consider admission for tonsillitis if the patient is…
- immunocompromised
- systematically unwell
- dehydrated
- has stridor
- has respiratory distress
- has evidece of peritonsillar abscess or cellulitis
How would you manage viral based acute tonsillitis?
- educate patients and parents
- Safety net - return if pain not settled after 3 days, or fever rises above 38.3C
- Simple analgesia
How would you manage bacterial acute tonsillitis?
Penicillin V = phenoxymethylpenicillin
10 day course
If allergic - Clarithromycin
What are complications of tonisillitis?
- Quinsy aka peritonsillar absces
- Otitis media
- Scarlet fever
- Rheumatic fever
- Post-strep glomerulonephritis
- Post-strep reactive arthritis
What is periorbital cellulitis (also called preseptal cellulitis)?
An infection of the soft tissues anterior to the orbital septum - this includes the eyelids, skin and subcutaneous tissue of the face, but not the contents of the orbit.
- What is pathophysiology of periorbital (preseptal) cellulitis?
- What organsisms commonly cause this infection?
- Infection spreads to structures around orbit from other sites = usually breaks in skin or local infections e.g. sinusiits, resp tract infections
- Staphylococcus aureus, staphylococcus epidermidis, Streptococci and anaerobic bacteria
What is the epidemiology of periorbital / preseptal cellulitis?
Children - usually under 10.
Median age = 21 months / around 2 years
More common in winter due to increased prevalence of respiratory tract infections
How does periorbital /preseptal cellulitis present?
- red, swollen, painful
- acute onset
- fever
O/E:
* erythema and odema of eyelid which can spread to surrounding skin
* partial or complete ptosis of eye due to swelling
Differentials of periorbital cellulitis?
Orbital cellulitis
Allergic reaction
What inv would you do for periorbital cellulitis?
- Bloods - raised inflammatory markers
- Swab of any discharge present
- Contrast CT of the orbit may help to differentiate between preseptal and orbital cellulitis. It should be performed in all patients suspected to have orbital cellulitis
How is periorbital cellulitis managed?
- All cases should be referred to secondary care for assessment
- Systemic antibiotics are frequently sufficient - usually co-amoxiclav (Iv or oral)
Children may require admission for observation as it can develop into orbital cellulitis
What is orbital cellulitis?
the result of an infection affecting the fat and muscles posterior to the orbital septum, within the orbit but not involving the globe
Presentation of orbital cellulitis?
- Redness and swelling around the eye
- Severe ocular pain
- Visual disturbance
- Proptosis
- Ophthalmoplegia/pain with eye movements
- Eyelid oedema and ptosis
- Drowsiness +/- Nausea/vomiting in meningeal involvement (Rare
What features would differentiate periorbital cellulitis from orbital cellulitis?
Orbital cellulitis has:
* reduced visual acuity,
* reduced eye movements
* proptosis (forward movement of eyeball),
* ophthalmoplegia/pain with eye movements
* abnormal pupil reactions
These are NOT consistent with preseptal cellulitis
What are RF for orbital cellulitis?
- Childhood - Mean age of hospitalisation 7-12 years
- Previous sinus infection
- Lack of Haemophilus influenzae type b (Hib) vaccination
- Recent eyelid infection/ insect bite on eyelid (periorbital cellulitis)
- Ear or facial infection
What investigations would you do for suspected orbital cellulitis?
- Full blood count – WBC elevated, raised inflammatory markers.
- Clinical examination involving complete ophthalmological assessment – Decreased vision, afferent pupillary defect, proptosis, dysmotility, oedema, erythema.
- CT with contrast – Inflammation of the orbital tissues deep to the septum, sinusitis.
- Blood culture and microbiological swab to determine the organism. Most common bacterial causes – Streptococcus, Staphylococcus aureus, Haemophilus influenzae B.
How is orbital cellulitis managed?
This is a MEDICAL EMERGENCY
Admission for IV abx
What is Rubella caused by?
Viral infection caused by togavirus
- How can child contract rubella?
- How long is incubation period for rubella?
- When are people infectious?
- Contracted during pregnancy in first 20weeks –> congenital rubella syndrome
- 14-21 days
- infectious from 7 days before symptoms appear to 4 days after onset of rash
Before - - - - how many - - - - weeks of gestation does rubella pose the highest risk to baby?
before 10 weeks of gestation
- damage to fetus is as high as 90% !
How can you prevent congenital rubella infection from mother?
Before getting pregnant:
* Women planning to become pregnant should ensure they have had the MMR vaccine.
* When in doubt, they can be tested for rubella immunity.
* If they do not have antibodies to rubella, they can be vaccinated with two doses of the MMR, three months apart.
When pregnant:
* Pregnant women should not receive the MMR vaccination, as this is a live vaccine.
* Non-immune women should be offered the vaccine after giving birth.
What are features of congenital rubella syndrome?
- Congenital sensiorineural deafness
- Congenital cataracts
- Congential heart disease - usually have PDA and pulmonary stenosis
- Learning diability
- Growth retardation
- Hepatosplenomegaly
- Purpuric skin lesions
- Salt and pepper chorioretinitis
- Microphthalmia
- Cerebral palsy
Dr Tom says know top 4 bullet points,.
When suspecting congenital rubella syndrome, what other condition should you investigate for, and why?
B19 Parovirus
Why? It’s hard to distinguish between parovirus and rubella so need to check both in serology.
In a women recently exposed to the rubella togovirus, what type of anitbodies will be raised?
IgM antibodies.
What commonly causes toxic shock syndrome?
Staphylococcal exotoxins = TSST-1 superantigen toxin
What is diagnostic criteria for toxic shock syndrome?
- fever: temperature > 38.9ºC
- hypotension: systolic blood pressure < 90 mmHg
- diffuse erythematous rash
- desquamation of rash, especially of the palms and soles
- involvement of three or more organ systems: e.g. gastrointestinal (diarrhoea and vomiting), mucous membrane erythema, renal failure, hepatitis, thrombocytopenia, CNS involvement (e.g. confusion)
How is toxic shock syndrome managed?
Remove infection focus - e.g. a retained tampon
IV fluids
IV antibiotics
Is viral gastroenteritis is contagious?
Highly contangious
What are the common causes of viral gastroenteritis?
- Norovirus
- Rotavirus
- Adenovirus - more subacute
What are differential diagnosis for child presenting with diarrhoea?
Infection (gastroenteritis)
Inflammatory bowel disease
Lactose intolerance
Coeliac disease
Cystic fibrosis
Toddler’s diarrhoea
Irritable bowel syndrome
Medications (e.g. antibiotics)
What is gastroenteritis?
How does it present?
Gastroenteritis is inflammation all the way from the stomach to the intestines and presents with nausea, vomiting and diarrhoea, fever and abdominal cramps, blood in stool.
What is main concern when a child presents with gastroenteritis?
Dehydration
How is gastroenteritis managed?
Mention all conservative measures that can be put in place.
Initially:
* Good hygiene helps prevent gastroenteritis.
* When patients develop symptoms they should immediately be isolated to prevent spread.
* Barrier nursing and rigorous infection control is important for patients in hospital to prevent spread to other patients.
* Children need to stay off school until 48 hours after the symptoms have completely resolved.
- A sample of the faeces can be tested with microscopy, culture and sensitivities to establish the causative organism and antibiotic sensitivities.
- The key to managing gastroenteritis is to ensure they remain hydrated whilst waiting for the diarrhoea and vomiting to settle.
- Attempt a fluid challenge.
- Rehydration solutions (e.g. dioralyte) can be used if tolerated.
- Dehydrated children or those that fail the fluid challenge may require IV fluids.
- Once oral intake is tolerated a light diet can be slowly reintroduced.
- Dry foods such as toast may be better tolerated.
What are possible post-gastroenteritis complications?
Lactose intolerance
Irritable bowel syndrome
Reactive arthritis
Guillain–Barré syndrome
How does upper resp tract infection present?
Coryzal symptoms - runny nose
Difficulty feeding
Difficulty breathing
Malaise / fatigue
O/E:
Acute pharyngitis - inflammed tonsils
Enlarged cervical lymph nodes
Inflamed tympanic membranes
Common age of presentation with viral URTI?
Toddlers starting nursery
Children starting school
Why are viral URTIs common in children of school age?
They become exposed to lots of viral infections they have no immunity to.
How is viral URTI managed?
Treated based on symptoms:
antipyretics - paracetamol
Saline drops for nasal congestion
No abx !
What are RF for URTI in children?
exposure to affected individuals
young age
winter season
day care attendance
What are RF for TB?
- Known contact with active TB
- Immigrants from areas of high TB prevalence
- People with relatives or close contacts from countries with a high rate of TB
- Immunosuppression due to conditions like HIV or immunosuppressant medications
- Homeless people, drug users or alcoholics
- Children less than 5 years old - esp for extrapulmonary TB
What organism causes TB?
Mycobacterium tuberculosis bacteria.
How is TB contracted in a person?
Inhalation of the bacteria in respiratory droplets that are releaseed when a person with infectious TB coughs
What areas does extrapulmonary TB affect?
- Lymph nodes. A “cold abscess” is a firm painless abscess caused by TB, usually in the neck. They do not have the inflammation, redness and pain you would expect from an acutely infected abscess.
- Pleura
- Central nervous system
- Pericardium
- Gastrointestinal system
- Genitourinary system
- Bones and joints
- Cutaneous TB affecting the skin
- What vaccine is offered for protection against TB?
- What are patients tested with before the vaccine?
- BCG vaccine which involves an intradermal infection of live attenuated TB (i.e. weakened TB)
- Mantoux test - only given vaccine if this is negative.
BCG vaccine is offered to patients that are at higher risk of contact with TB. Who does this include?
- Neonates born in areas of the UK with high rates of TB
- Neonates with relatives from countries with a high rate of TB
- Neonates with a family history of TB
- Unvaccinated older children and young adults (< 35) who have close contact with TB
- Unvaccinated children or young adults that recently arrived from a country with a high rate of TB
- Healthcare workers
What is the mantoux test?
- used to look for a previous immune response to TB. This indicates possible previous vaccination, latent or active TB.
- this involves injecting tuberculin (proteins from TB) into the intradermal space on the forearm.
- injecting the tuberculin creates a bleb under the skin. After 72 hours the test is “read”. This involves measuring the induration of the skin at the site of the injection. NICE suggest considering an induration of 5mm or more a positive result. After a positive result they should be assessed for active disease.
How does TB present?
In children can present with non specific S+S:
* poor weight gain
* faltering growth / failure to thrive
* fatigue
* persistent fever
More general symptoms:
* Lethargy
* Fever or night sweats
* Weight loss
* Cough with or without haemoptysis
* Lymphadenopathy
* Erythema nodosum
* Spinal pain in spinal TB (also known as Pott’s disease of the spine)
What investigations would you do for suspected TB?
CXR
* to look for upper lobe cavitation (in reactivated TB)
* bilateral hilar lymphadenopathy
Sputum smear:
* stained for presence of acid-fast bacilli (Ziehl-Neelsen stain)
Cultures:
* sputum culture = gold standard
* Mycobacterium blood cultures
* Lymph node aspiration or biopsy
NAAT - nucleic acid amplification test
* looks for DNA of TB bacteria
What is benefit of NAAT tests for TB?
Allows for rapid diagnosis within 24-48hrs
More sensitive than smear (but less sensitive than a culture)
Why are sputum cultures the gold standard investigation for TB?
More sensitive than sputum smear and NAAT
Can assess drug sensitivities
Who should be screened for TB?
Asymptomatic people at high risk of infection
* if been in contact with person w active pulmonary or laryngeal TB
* immunocompromised
* new to the UK
DDx for presentation of TB?
Viral URTI
Asthma
Chest infection
Lung fibrosis
(v unlikely for children - but COPD and lung cancer are mentioned in NICE too)
What does primary TB show on CXR?
Patchy consolidation, pleural effusions and hilar lympadenopathy
What does reactivated TB show on CXR
TB revision
Patchy or nodular consolidation
Cavitation usually in upper zones
What does disseminated miliary TB show on CXR?
See picture of ‘millet seeds’ uniformly distributed throughout lung fields.
How is acute pulmonary TB managed?
(from 1month old and above)
Management of active TB is coordinated by a specialist TB service with an MDT approach.
RIPE is the mnemonic used to remember the treatment for TB. It involves a combination of 4 drugs used at the same time:
R – Rifampicin for 6 months
I – Isoniazid for 6 months
P – Pyrazinamide for 2 months
E – Ethambutol for 2 months
- What is common side effect of isoniazid?
- What should be co-prescribed with it?
- What are other side effects of this drug?
- Peripheral neuropathy
- Pyridoxine (vitamin B6)
- hepatitis, agranuolocytosis
Can rememeber by I’m-so-numb-azid
Apart from pharmacological management, what else should you do to manage pt with TB?
- Test for other infectious diseases (HIV, hepatitis B and hepatitis C).
- Test contacts for TB.
- Notify Public Health of all suspected cases.
- Patients with active TB should be isolated to prevent spread until they are established on treatment (usually 2 weeks). In hospital negative pressure rooms are used to prevent airborne spread. Negative pressure rooms have ventilation systems that actively remove air to prevent it spreading out on to the ward.
- Management and followup should be guided by a specialist MDT.
- Treatment is slightly different for extrapulmonary disease and often includes using corticosteroids.
- Individualised drug regimes are required for multidrug‑resistant TB.
What are side effects of Pyrazinamide?
Can cause hyperuricaemia (high uric acid levels ) so causes gout
Arthralgia, myalgia
Hepatitis
What are side effects of Rifampicin?
- can cause red/orange discolouration of secretions like urine and tears.
- It is a potent inducer of cytochrome P450 enzymes therefore reduces the effect of drugs metabolised by this system. This is important for medications such as the contraceptive pill.
- Flu like symptoms
Red-an-orange-pissin
What are side effects of Ethambutol?
Colour blindness
Reduced visual acuity - optic neuritis
‘Eye-thambutol’
What TB drugs are associated to hepatotoxicity?
Rifampicin
Isoniazid
Pyrazinamide
- How is measles contracted?
- How long is incubation period/ when do symptoms start?
- When is measles infective from?
- respiratory droplets through aerosol transmission
- 10-14 days
- from prodrome until 4 days after rash starts
What is the presentation of measles?
- Fever, coryzal symptoms, irritability and conjunctivitis.
- Koplik spots typically develop before the rash and are white spots (‘grain of salt’) on the buccal mucosa
- rash starts behind ears (3-5 days after fever) then to the whole body
- rash is discrete maculopapular rash becoming blotchy & confluent
desquamation that typically spares the palms and soles may occur after a week - diarrhoea occurs in around 10% of patients
What feature are pathognomonic for measles (i.e. after seeing this feature, you can diagnose measles)?
Koplik spots
What are complications of measles?
- Most common = otitis media, which can cause hearing loss.
- Pneumonia = most common cause of death
- Diarrhoea
- Dehydration
- Encephalitis = usually 1-2 weeks after illness onset.
- Meningitis
- Vision loss = due to keratoconjunctivitis, corneal ulceration
- Death
What is management for measles?
Mainly supportive
Admission if immunosuppressed child
Isolate until 4 days after symptoms resolve
Notifiable disease - so report to public health
If child not immunised has come into contact with measles, MMR should be offered and given within 72hrs.
What is scarlet fever?
* describe cause
* ages it affects
* how it is spread
- A reaction to erythrogenic toxins produced by Group A haemolytic streptococci (usually Streptococcus pyogenes in tonsillitis ).
- It is more common in children aged 2 - 6 years with the peak incidence being at 4 years.
- spread via resp route by inhaling or ingesting resp droplets or by direct contact with nose and throat discharges - i.e sneezing, coughing.
Presentation of scarlet fever?
- fever: typically lasts 24 to 48 hours
- malaise, headache, nausea/vomiting
- sore throat
- ‘strawberry’ tongue
- rash –> a red-pink, blotchy, macular rash with rough “sandpaper” skin that starts on the trunk and spreads outwards. Rash described as fine punctate erythema (‘pinhead’). Spares palms and soles.
- Patients can have red, flushed cheeks.
- cervical lymphadenopathy
How is scarlet fever managed?
- oral penicillin V for 10 days
- patients who have a penicillin allergy should be given azithromycin
- children can return to school 24 hours after commencing antibiotics
- scarlet fever is a notifiable disease
Complications of scarlet fever?
Otitis media
Rheumatic fever
Acute post-streptococcal glomerulonephritis
Presentation of parovirus B19?
- mild fever
- coryza
- non-specific viral symptoms - myalgia, lethargy
- 2-5 days in = diffuse bright red rash on both cheeks ‘slapped cheek’
- reticular mildly erythematous rash on trunk and limbs that is raised and itchy
Management of parovirus b19?
self-limiting
rash fades over 1-2 weeks
fluids and analgesia
no longer infectious after rash forms
Who is at risk of complications from parovirus B19?
- immunocompromised
- pregnant (can affect fetus in first 20 weeks)
- sickle cell anaemia
- thalassaemia
- hereditary spherocytosis
- haemolytic anaemia
What are complications of parovirus?
Aplastic anaemia
Encephalitis or meningitis
Pregnancy complications - fetal death
What is roseola infantum?
A common disease of infancy caused by the human herpes virus 6 (HHV6).
It has an incubation period of 5-15 days and typically affects children aged 6 months to 2 years.
Presentation of roseola infantum?
- presents 1 – 2 weeks after infection with a high fever (up to 40ºC)
- fever comes on suddenly, lasts for 3 – 5 days and then disappears suddenly.
- there may be coryzal symptoms, sore throat and swollen lymph nodes during the illness.
- When the fever settles, the rash appears for 1 – 2 days. The rash consists of a mild erythematous macular rash across the arms, legs, trunk and face and is not itchy.
- Nagayama spots on the uvula and soft palate
- febrile convulsions due to high temperature
What are complications of roseola infantum?
febrile convulsions due to high temp
In immunocompromised = myocarditis, thrombocytopenia, guillain-barre syndrome
Primary Immunodeficiency
Define SPUR
Serious
Persistent
Unusual
Recurrent
PID
What would you ask in Hx of pt with suspected PID?
Infection history:
* site - different sites?
* frequency
* need for IV abx/admission in past for Infections
* microbiology - what organisms were identified in past infections?
Immunisation history
* have they got an infection because of a vaccine they have had
* have they had a poor vaccine response
Family history
* infections
* autoimmunity
* consanguinity
* neonatal deaths
Compare and contrast the innate immune system to the adaptive immune system, commenting on:
1. specificity?
2. time for resposne
3. cells involved
Innate vs Adaptive
1. non-specific vs pathogen specific
2. rapid onset vs slower onset
3. macrophages, complement and neutrophils vs B cells and T cells
List the categories of PID (primary immunodeficiency)
Antibody (B cells)
Combined (T cell +)
Complement
Phagocyte disorders
Those associated with syndromes
What is a common antibody deficiency (B cell)
X linked agammaglobulinaemia (XLA)
Others: common variable immunodeficiency, specific antibody deficiency, transient hypogammaglobulinaemia of infancy (goes away as child ages)
Name the types of antibodies and what they do
IgG = main one in blood, has lots of subtypes, part of memory response
IgM = early response, binds complement, has limited memory
IgA = most abundant overal, in the mucosa
IgE = for mast cell activation, allergy and parasitic repsonse
IgD
PID
Describe presentation of antibody deficiency infections
- Starts at around 4-6 months old
- Sino-pulmonary infections - encapsulated bacteria found
- Hospital admissions in the past
- Has CXR changes
- Gets recurrent otitis media with discharge
- May present with diarrhoea from giardia infection
Describe pathophysiology of X linked agammaglobulinaemia
X linked condition
Defect in B cell tyrosine kinase gene which is responsible for differentiation and maturation of B cells (so they become functional)
So can not respond to infection
How is Antibody deficiency PID (such as XLA) managed?
For XLA = IgG immunoglobulin replacement - given SC or IV
For others = prompt, prolonged anbx needed. Can consider abx prophylaxis.
What cells are affected in Combined Immune deficiencies (CID)?
T cell defects +/- others
Usually also affects antibodies too as there is interaction between T cells. and B cells to make antibodies.
What is function of T cells?
* mention function of CD4, CD8 and Tregs (regulatory T cells)
CD4:
* helper T cells, activate macrophages and B cells
CD8:
* these are cytotoxic
* anti-viral, induce apoptosis, anti-tumour
Tregs:
* immuoregulatory so body can recognise own cells as self; loss of these = autoimmunity
What are the types of combined immunodeficiency (CID)?
SCID = severe combined immunodeficiency
* All immunoglobulins production affected
* Presents in adulthood at 20-35yrs.
* Have recurrent respiratory and sinus infections.
HyperIgM syndrome
* defect in CD40 ligand
* Can not switch classes from IgM to IgG or IgA
Complete Di George
* No thymus
* So no T cells
* Presents like SCID
How do T cell combined immune deficiences (CID) present
(e.g. SCID, DiGeorge, HyperIgM)
- recurrent bacterial infections
- viral infections- systemic and persistent
- mycobacteria infections
- Candida infections
- aspergillus infections
- chronic diarrhoea and failure to thrive/faltering growth
May also present with low lymphocytes from blood test - < 2.8x10(9) /L before age of 1.
How is CID managed?
- SCID = need bone marrow transplant before significant morbidity
- Prophylactic abx and antifungals
- Immunoglobulin replacement
- Infection prevention measures - e.g. stop children playing in soil to prevent aspergillus
- use CMV negative, irradiated blood products
- Avoid live vaccines
What are functions of the complement?
- Part of the innate immune system
- Opsonisation = so will flag cells for phagocytosis
- Chemo-attraction to recruit more phagocytes
- Membrane attack complex will create holes in certain types of bacteria - e.g. encapsulated.
Complement disorders infection: how does it present?
- Recurrent invasive bacterial infections such as meningitis and pneumonia
- meningococcal, pneumococcal, Hib infections
- frequent sinopulmonary infection by the usual organisms
How are complement disorders managed?
- Penicillin prophylaxis
- Require additional immunisations - Men ACWY, MenB, Pnemovax (give this one after 5yrs old)
- Check green book for immunisations against infectious diseases
What is the role of neutrophils?
- Phagocytosis of bacteria and fungi
- Act as antigen presenting cells
PID
Name phagocyte disorders commonly seen in paeds immunology
Chronic Granulomatous Disease
Severe congenital neutropenia
Leucocyte adhesion defects
Bold = main one
What is chronic granulomatous disease - type of inheritance and presentation?
X linked or autosomal recessive
Presentation:
* recurrent abseccess from Staph aureus infections
* Liver abscess
* fungal chest infections
* osteomyelitis
* BCG-itis
* Early onset IBD - presents alongside this
PID
How are phagocyte disorders managed?
- Antifungal and antibiotic prophylaxis
- avoid fungal spores e.g. compost, leaves in garden
- Avoid BCG
- Consider bone marrow transplant if have an early diagnosisi
What syndromes are associated to immune deficiency?
DiGeorges
CHARGE
Ataxia Telangiectasia
How are syndromes associated to immune deficiency (DiGeorges, CHARGE etc) managed?
- These are usually to do with T cell type immunodeficiency - so need antibiotic prophylaxis if severe
For complete DiGeorge whcih can present like SCID:
* abx prophylaxis
* thymic transplant
For associated syndromes of PID (e.g. DiGeorges, charge etc), what other features are present that predispose these patients to frequent infections?
- Poor tone so have weak cough
- Reflux
- Indwelling devices
What investigations would you do for PID?
- FBC
- Lymphocyte subsets
- Total antibodies
- Specific antibodies - look at vaccination history
- neutrophil oxidative burst - to see if they are working normally (if not - could be phagocyte disorder)
- Complement levels
- HIV status
