Paediatrics - Dermatology, Allergy and Infectious disease Flashcards
A child presents with a non-blanching purple rash after having fever and lethargy. What is the diagnosis?
What causes the purpura
Meningococcal septicaemia refers to the meningococcus bacterial infection in the bloodstream. Meningococcal septicaemia is the cause of the classic “non-blanching rash” that everybody worries about. This rash indicates the infection has caused disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages.
Neisseria meningitidis is a gram-negative diplococcus bacteria. They are circular bacteria (cocci) that occur in pairs (diplo-). It is commonly known as meningococcus.
IT IS NOT THE SAME AS MENINGOCOCCAL MENINGITIS - they can be co-morbid or patients can simply have either (can have menigogococcal mengitis with the rash).
Meningococcal meningitis is when the bacteria is infecting the meninges and the cerebrospinal fluid around the brain and spinal cord.
What are the two most common causes of bacterial meningitis?
In neonates?
The most common causes of bacterial meningitis in children and adults are Neisseria meningitidis (meningococcus) and Streptococcus pneumoniae (pneumococcus).
In neonates the most common cause is group B strep (GBS). GBS is usually contracted during birth from GBS bacteria that live harmlessly in the mother’s vagina.
Presentation of meningitis:
- symptoms?
- Sx and Ix in infants?
- Special tests?
Sx:
- fever
- neck stiffness
- vomiting
- headache
- photophobia
- altered conciousness and seizures
Me - fever with neffstickness and headache is key, neck stiffness isnt seen in migraine or febrile convulsions (6 mths - 5y/o)
Neonates and babies can present with very non-specific signs and symptoms, such as hypotonia, poor feeding, lethargy, hypothermia and a bulging fontanelle.
NICE recommend a lumbar puncture as part of the investigations for all children:
Under 1 month presenting with fever
1 to 3 months with fever and are unwell
Under 1 year with unexplained fever and other features of serious illness
There are two special tests you can perform to look for meningeal irritation:
Kernig’s test
Brudzinski’s test
Kernig’s test involves lying the patient on their back, flexing one hip and knee to 90 degrees and then slowly straightening the knee whilst keeping the hip flexed at 90 degrees. This creates a slight stretch in the meninges. Where there is meningitis it will produce spinal pain or resistance to movement.
Brudzinski’s test involves lying the patient flat on their back and gently using your hands to lift their head and neck off the bed and flex their chin to their chest. In a positive test this causes the patient to involuntarily flex their hips and knees.
Management of bacterial meningitis in children:
Ix?
Rx?
Post exposure prophalaxis?
Meningococcal septicaemia and bacterial meningitis are medical emergencies and should be treated immediately.
Ix:
- blood culture
- lumbar punture
- Blood test for meningococcal PCR
Rx:
- Under 3 months – cefotaxime plus amoxicillin (the amoxicillin is to cover listeria contracted during pregnancy)
- Above 3 months – ceftriaxone plus dexamethsone (prevent hearing loss and neurological damage)
- notifiable disease
PEP:
Significant exposure to a patient with meningococcal infections such as meningitis or septicaemia puts people at risk of contracting the illness (direct contact through respiratory secretions). This risk is highest for people that have had close prolonged contact within the 7 days prior to the onset of the illness
The usual antibiotic choice for this is a single dose of ciprofloxacin. It should be given as soon as possible and ideally within 24 hours of the initial diagnosis.
Cause of viral meningitis?
Ix?
Rx?
- HSV
- enterovirus
- VZV
Ix - same as above to rule out bacteria but the CSF from lumbar puncture should be sent for viral PCR tesitng
Viral meningitis tends to be milder than bacterial and often only requires supportive treatment. Aciclovir can be used to treat suspected or confirmed HSV or VZV infection.
Interpretation of CSF results in meningitis
A lumbar puncture involves inserting a needle into the lower back to collect a sample of cerebrospinal fluid (CSF). The spinal cord ends at the L1 – L2 vertebral level, so the needle is usually inserted into the L3 – L4 intervertebral space. Samples are sent for bacterial culture, viral PCR, cell count, protein and glucose. A blood glucose sample should be sent at the same time so that it can be compared to the CSF sample. The samples need to be sent immediately.
Bacterial vs Viral?
TOM TIP: Interpreting lumbar puncture results is a common exam question. It is easier to think about what will happen to the CSF with bacteria or viruses living in it rather than trying to rote learn the results. It makes sense that bacteria swimming in the CSF will release proteins and use up the glucose. Viruses don’t use glucose but may release a small amount of protein. The immune system releases neutrophils in response to bacteria and lymphocytes in response to viruses.
Bacterial:
- cloudy
- high protein
- low glucose
- high neutrophils
- positive culture
Viral:
- clear
- normal or mildly raised protein
- normal glucose
- high lyphocyte count
- culture negative
complications of meningitis - 1 key one
Hearing loss is a key complication
Seizures and epilepsy
Cognitive impairment and learning disability
Memory loss
Cerebral palsy, with focal neurological deficits such as limb weakness or spasticity - i think only for infants?
Presentation of encephalitis?
Most common cause of encephalitis? Others?
Presentation
- altered conciousness
- altered behavoir and impaired cognition
- acute onset of focal neurological symptoms
- acute onset of focal seizures
- fever
Unlike meningitis with headache, photophobia, neck stiffness, vomiting, fever
Cause
Encephalitis means inflammation of the brain. This can be the result of infective or non-infective causes. Non-infective causes are autoimmune, meaning antibodies are created that target brain tissue.
The most common cause is infection with a virus. Bacterial and fungal encephalitis is also possible although much more rare in the UK.
The most common viral cause is herpes simplex virus (HSV). In children the most common cause is herpes simple type 1 (HSV-1) from cold sores. In neonates it is herpes simplex type 2 (HSV-2) from genital herpes, contracted during birth.
Other viral causes include varicella zoster virus (VZV) associated with chickenpox, cytomegalovirus associated with immunodeficiency, Epstein-Barr virus associated with infectious mononucleosis, enterovirus, adenovirus and influenza virus. It is important to ask about vaccinations, as the polio, mumps, rubella and measles viruses can cause encephalitis as well.
Encephalitis
Diagnosis?
Management?
Lumbar puncture - CSF for viral PCR testing
CT scan is LP is contraindicated (GCS <9, haemodynamically unstable, active seizsure)
MRI scan after the lumbar puncture to visualise the brain in detail
Others
Swabs of other areas can help establish the causative organism, such as throat and vesicle swabs
HIV testing is recommended in all patients with encephalitis
Management:
- Intravenous antiviral medications are used to treat the suspected or confirmed underlying cause:
Aciclovir treats herpes simplex virus (HSV) and varicella zoster virus (VZV) - usually started empirically until results are available
Ganciclovir treat cytomegalovirus (CMV)
- Repeat lumbar puncture is usually performed to ensure successful treatment prior to stopping antivirals
What is Kawasaki disease?
key complication?
Presentation?
Kawasaki disease is also known as mucocutaneous lymph node syndrome. It is a systemic, medium-sized vessel vasculitis.
It affects young children, typically under 5 years. There is no clear cause or trigger. It is more common in Asian children, particularly Japanese and Korean children. It is also more common in boys.
A key complication is coronary artery aneurysm.
Presentation:
A key feature that should make you consider Kawasaki disease is a persistent high fever (above 39ºC) for more than 5 days. Children will be unhappy and unwell. The key skin findings are a widespread erythematous maculopapular rash and desquamation (skin peeling) on the palms and soles of the feet.
Other features include:
Strawberry tongue (red tongue with large papillae)
Cracked lips
Cervical lymphadenopathy
Bilateral conjunctivitis
TOM TIP: If you come across a child with a fever persisting for more than 5 days, think of Kawasaki disease! A rash, strawberry tongue, lymphadenopathy and conjunctivitis will seal the diagnosis in your exams.
Investigations in kawasaki disease
There are several investigations that can be helpful in Kawasaki disease:
Full blood count can show anaemia, leukocytosis and thrombocytosis
Liver function tests can show hypoalbuminemia and elevated liver enzymes
Inflammatory markers (particularly ESR) are raised
Urinalysis can show raised white blood cells without infection
Echocardiogram can demonstrate coronary artery pathology
Disease course of kawasaki disease?
management?
further investigation that is indicated?
Disease Course
There are three phases to Kawasaki disease:
Acute phase: The child is most unwell with the fever, rash and lymphadenopathy. This lasts 1 – 2 weeks.
Subacute phase: The acute symptoms settle, the desquamation and arthralgia occur and there is a risk of coronary artery aneurysms forming. This lasts 2 – 4 weeks.
Convalescent stage: The remaining symptoms settle, the blood tests slowly return to normal and the coronary aneurysms may regress. This last 2 – 4 weeks.
Management
There are two first line medical treatments given to patients with Kawasaki disease:
High dose aspirin to reduce the risk of thrombosis
IV immunoglobulins to reduce the risk of coronary artery aneurysms
Patients will need close follow up with echocardiograms to monitor for evidence of coronary artery aneurysms.
TOM TIP: Kawasaki disease is one of the few scenarios where aspirin is used in children. Aspirin is usually avoided due to the risk of Reye’s syndrome. This is a unique fact that examiners like to test.
A child presents with:
- a red-pink, blotchy, macular rash with rough “sandpaper” skin that starts on the trunk and spreads outwards
- fever
- flushed cheeks
- sore throat
- strawberry tongue
- cervical lymphadenopathy?
Diagnosis?
Management?
Scarlet fever is associated with group A streptococcus infection, usually tonsillitis. It is not caused by a virus.
Treatment is with antibiotics for the underlying streptococcal bacterial infection. This is with phenoxymethylpenicillin (penicillin V) for 10 days. Scarlet fever is a notifiable disease and all cases need to be reported to public health. Children should be kept off school until 24 hours after starting antibiotics.
Patients can have other conditions associated with group A strep infection:
Post-streptococcal glomerulonephritis
Acute rheumatic fever
The other disease causing strawberry tongue and cervical lyphadenopathy is kawasaki disease, but here the fever is likely to last more than five days are there is often desquamatisation of the palms and soles of feet.
A child presents with:
- fever
- coryzal symptoms
- conjuctivitis
- 3-5 days later a macular (flat) rash appears on the face, behind the ears and then spreads to the rest of the body
Diagnosis?
pathognomonic sign?
management?
complications?
Measles is caused by the measles virus. It is highly contagious via respiratory droplets. Symptoms start 10 – 12 days after exposure, with fever, coryzal symptoms and conjunctivitis.
Koplik spots are greyish white spots on the buccal mucosa. They appear 2 days after the fever. They are pathognomonic for measles, meaning if a patient has Koplik spots, you can diagnose measles.
The rash starts on the face, classically behind the ears, 3 – 5 days after the fever. It then spreads to the rest of the body. The rash is an erythematous, macular rash with flat lesions.
Measles is self resolving after 7 – 10 days of symptoms. Children should be isolated until 4 days after their symptoms resolve. Measles is a notifiable disease and all cases need to be reported to public health. 30% of patients with measles develop a complication.
Complications include:
Pneumonia
Diarrhoea
Dehydration
Encephalitis
Meningitis
Hearing loss
Vision loss
Death
What causes slapped cheek syndrome/erythema infectiosum?
Presentation?
Management?
Complications?
Parovirus B19
Parvovirus infection starts with mild fever, coryza and non-specific viral symptoms such as muscle aches and lethargy. After 2 – 5 days the rash appears quite rapidly as a diffuse bright red rash on both cheeks, as though they have “slapped cheeks”. A few days later a reticular mildly erythematous rash affecting the trunk and limbs appears that can be raised and itchy. Reticular means net-like.
The illness is self limiting and the rash and symptoms usually fade over 1 – 2 weeks. Healthy children and adults have a low risk of any complications and are managed supportively with plenty of fluids and simple analgesia. It is infectious prior to the rash forming, but once the rash has formed they are no longer infectious and do not need to stay off school.
Patients that are at risk of complications include immunocompromised patients, pregnant women and patients with haematological conditions.such as sickle cell anaemia, thalassaemia, hereditary spherocytosis and haemolytic anaemia. These patients require serology testing for parvovirus to confirm the diagnosis and checking of the full blood count and reticulocyte count for aplastic anaemia. People that would be at risk of complications that have come in contact with someone with parvovirus prior to the rash forming, should be informed and may need investigations.
Complications:
**Aplastic anaemia
**Encephalitis or meningitis
Pregnancy complications including fetal death
Rarely hepatitis, myocarditis or nephritis
Key differential is scarlet fever because of the fever and flushed flushed cheeks. However scarlet fever caused by GA strept has a sandpaper rash, cervical lyphadenopathy, and strawberry tongue.
What is an exanthem and list causes of them
An “exanthem” is an eruptive widespread rash
- measels
- scarlet fever
- slapped cheeks syndrome
- rubella
- roseola infantum
- kawasaki disease
