Paediatrics NOTES 2 Flashcards
What causes chickenpox?
Primary infection with the varicella zoster virus
What is shingles?
The reactivation of the dormant virus in the dorsal root ganglion
How is chickenpox spread?
Via respiratory route, can be caught from someone with shingles
When is chickenpox infectious?
4 days before the rash, until 5 days after it appears
What is the incubation period of chickenpox?
10-21 days
What is the disease course for chickenpox?
Prodrome fever. Then itchy rash, starting on head/trunk then spreading. Initially macular then papular then vesicular.
When is chickenpox no longer infectious?
When the lesions are dry and have crusted over
Who should receive varicella zoster immunoglobulin?
Immunocompromised patients and newborns with peripartum exposure
What lotion should be given to help calm chicken pox scratching?
Calamine
When should IV aciclovir be considered in chickenpox?
immunocompromised patients and newborns with peripartum exposure who have recieved varicella zoster immunoglobulin (VZIG). If chickenpox develops then IV aciclovir should be considered
What is a common complication of chickenpox?
Secondary bacterial infection of the lesions
What might increase the risk of secondary bacterial infection of chickenpox lesions?
NSAIDs
If there is secondary bacterial infection of chickenpox, what can then happen to the infection?
Commonly it is just a small area of cellulitis, but in a small number of patients, invasive group A streptococcal soft tissue infections may occur resulting in necrotizing fasciitis
What are the possible complications of chickenpox?
Pneumonia, encephalitis, arthritis, nephritis, pancreatitis
When does chicken pox infection typically occur?
ages 1 to 6 years, maximal transmission during winter and spring
What are the features of fetal varicella syndrome (if baby encounters chickenpox whilst in utero)?
Skin scarring, eye defects, limb hypoplasia, microcephaly, learning disabilities
Who should recieve vaccination against primary varicella infection?
- healthcare workers who are not already immune to VZV
- contacts of immunocompromised patients
What dermatomes are most commonly affected by shingles?
T1-L2 (trunk)
What are the prodromal period for shingles?
Burning pain over the affected dermatome for 2-3 days, pain may be severe and interfere with sleep
What is the characteristic rash of shingles?
Initially erythematous, macular rash over the affected dermatome. Becomes vesicular Well demarcated by the dermatome
When are patients with shingles infectious?
Until the vesicles have crusted over
What causes diphtheria?
Gram positive corynebacterium diphtheriae
What is the diphtheric membrane seen in diphtheria infection?
Membrane on tonsils caused by necrotic mucosal cells. Grey, pseudomembrane on the posterior pharyngeal wall
What is the presentation of diphtheria?
Sore throat with diphtheric membrane, bulky cervical lymphadenopathy, high temperature, sore throat, difficulty breathing and swallowing
How is diphtheria diagnosed?
Culture of throat swab; uses tellurite agar or Loeffler’s media
What is the pathophysiology of diphtheria?
Exotoxin is released, which leads to necrosis of tissue
What is the management of diphtheria?
Antitoxin (must be given quickly, won’t work once the exotoxin is bound with tissues), and antibiotics
What antibiotics are given in diphtheria?
Erythromycin or IM penicillin
What is the cause of tuberculosis?
Mycobacterium tuberculosis
What is the pathophysiology of tuberculosis?
Primary infection of the lungs occurs. A small lung lesion (Ghon focus) develops. This is composed of tubercle-laden macrophages. Leads to granuloma formation, with necrosis in the centre. This either heals by fibrosis via a type 4 hypersensitivity reaction, though in immunocompromised disseminated disease may occur
What is the gold standard diagnosis method of TB?
Sputum culture
How is latent tuberculosis diagnosed?
Mantoux test (inject tuberculin in the intradermal space in forearm). If >5mm= positive result
What is a ghon focus in tuberculosis?
pulmonary lesion (disease laden macrophages) with ipsilateral hilar lymph node involvement
What drugs are given in TB, and what are the side effects?
Rifampicin, isoniazid, pyrazinamide, ethambutol
What are side effects of TB drugs?
R: orange/red urine
I: burning sensation in feet
P: joint pains
E: visual impairment
4 for 2 months, 2 for 4 months
What is the presentation of TB in children?
chronic cough, haemoptysis, lethargy, fever or night sweats, weight loss, lymphadenopathy, erythema nodosum (tender, red nodules on the shins cause by inflammation of subcutaneous fat), spinal pain
What is erythema nodosum?
Tender, red nodules on the shins caused by inflammation of subcutaneous fat
What does acid fast mean in the context of TB?
M.tuberculosis has a waxy coating, makes gram staining ineffective. Resistant to acids used to stain; making them acid fast
What stain is used to diagnose TB?
Zeihl-Neelsen stain
What is seen on a chest xray in a patient with disseminated miliary tuberculosis?
Millet seeds (small nodules throughout the lungs)
What is usually prescribed alongside Isoniazid and why?
Pyridoxine (vitamin B6): reduces peripheral neuropathy
What are the most common causes of bacterial meningitis in children and adults?
Neisseria meningitidis (meningococcus) and streptococcus pneumoniae (pneumococcus)
What is the commonest cause of bacterial meningitis in neonates?
Group B strep
What is meningococcal septicaemia referring to?
A meningococcus bacterial infection in the bloodstream
What causes the classic non-blanching rash in meningococcal septicaemia?
Infection has caused DIC and subcutaenous haemorrhages
Do all forms of meningococcal septicaemia present with a non-blanching rash?
No, classically only meningococcal septicaemia
What is the classic presentation of meningitis?
Fever, neck stiffness, vomiting, headache, photophobia, altered consciousness, seizures
What are signs of bacterial meningitis that might present in neonates/babies?
Generally very non specific. Hypotonia, poor feeding, lethargy, hypothermia, bulging fontanelle
When do NICE recommend lumbar puncture as part of investigations?
All children:
- under 1 month presenting with fever
- 1 to 3 months with fever and unwell
- under 1 year with unexplained fever and other signs of illness
What are the special tests that can look for meningeal irritation?
Kernig’s test, Brudzinski’s test
What is kernig’s test?
Lie the patient on their back, flex one hip and knee to 90 degrees, then slowly straighten the knee whilst keeping the hip flexed at 90 degrees. Creates slight stretch in the meninges; if meningitis, will produce spinal pain
What is Brudzinski’s test?
Lie patient flat on back, gently lift head and neck off bed and flex chin to their chest. Will cause patient to involuntarily flex their hips and knees
How should suspected meningococcal meningitis be treated in the community?
Stat IM BenPen
How should meningococcal meningitis be dx?
meningococcal PCR (tests directly for meningococcal DNA)
When is vancomycin added to meningitis treatment regime?
Risk of penicillin resistant pneumococcal infection, for example recent foreign travel or prolonged antibiotic exposure
Why are steroids used in meningitis treatment? What is the regime, and for what age?
Reduce frequency and severity of hearing loss and neurological damage. Dexamethasone given 4 times daily for 4 days to children over 3 months
What is the treatment for meningitis (under 3 months vs over 3 months)?
- under 3 months: cefotaxime plus amoxicillin
- over 3 months: ceftriaxone
What is the prophylaxis treatment for meningitis?
Single dose of ciprofloxacin
Is viral or bacterial meningitis worse?
Viral tends to be milder and require only supportive treatment
What are the most common causes of viral meningitis?
Herpes simplex, enterovirus, varicella zoster virus
What are potential complications of meningitis?
- sensorineural hearing loss
- seizures and epilepsy
- memory loss
- cerebral palsy with focal neurological deficits
What is found in a CSF sample with bacterial infection present?
Cloudy, high protein, low glucose, high neutrophils
What is found in a CSF sample with viral infection present?
Clear, normal protein and glucose, high lymphocytes
Why is amoxicillin given to neonates with meningitis?
To cover listeria infection
What is Waterhouse-Friderichsen syndrome, and how does it link to meningococcal meningitis?
Patients with meningococcal meningitis are at risk of Waterhouse-Friderichsen syndrome (adrenal insufficiency secondary to adrenal haemorrhage).
What are contraindications to performing a lumbar punctures?
- focal neurological signs
- papilloedema
- significant bulging of the fontanelle
- DIC
- signs of cerebral herniation
What is the treatment of meningitis that may be viral, before cultures return?
If suspected viral, still start on broad spectrum IV abx until results back
What is encephalitis?
Inflammation of the brain
What is the most common cause of encephalitis?
Infection with a virus; most commonly herpes simplex virus. Also varicella zoster virus.
Which type of herpes simplex virus most commonly causes encephalitis (children vs neonates)
Children: HSV-1 from cold sores
Neonates: HSV-2 from genital herpes
What is the presentation of encephalitis?
Altered consciousness, altered cognition, unusual behaviour, acute onset focal neurological symptoms, acute onset focal seizures, fever
What is the diagnosis of encephalitis?
- LP: CSF for viral PCR
- CT scan (if LP C/I)
- MRO scan
- EEG
- HIV testing
What is the management of encephalitis?
Antiviral medications: aciclovir (used empirically)
What investigation is done before stopping antiviral medication?
Repeat lumbar puncture to ensure successful treatment
What parts of the brain are typically affected in encephalitis?
Temporal and inferior frontal lobes
What is impetigo?
Superficial bacterial skin infection
What typically causes impetigo?
S.aureus (though rarely also S.pyogenes)
What is the characteristic presentation of a staphylococcus skin infection?
A golden crust
What is the difference between bullous and non bullous impetigo? Which is more common?
Non-bullous; blisters are not present. Most common
Bullous: fluid filled blisters present.
Why does impetigo occur?
When bacteria enters via a break in the skin. Can occur also related to eczema or dermatitis
Where does non-bullous impetigo typically occur?
Around the mouth or nose
What is the treatment for localised non-bullous impetigo?
Hydrogen peroxide 1% cream is first line. Then topical fusidic acid
What is the treatment for wide spread or severe impetigo?
Oral flucloxacillin
What causes the vesicles in bullous impetigo?
Due to s.aureus bacteria, which produce epidermolytic toxins that break down the proteins holding skin cells together. Causes 1-2cm fluid filled vesicles.
Is there systemic symptoms in impetigo?
Non-bullous: no
Bullous: yes (feverish and generally unwell)
What is severe infections with widespread bullous impetigo lesions called?
Staphylococcus scalded skin syndrome
How is bullous impetigo diagnosed?
Swabs of the vesicles
What is the treatment of bullous impetigo?
Oral or IV flucloxacillin
What are possible complications of impetigo?
Cellulitis, sepsis, scarring, Staphylococcus scalded skin syndrome
How is impetigo spread?
Spread is by direct contact with discharges from the scabs of an infected person. The bacteria invade the skin through minor abrasions and then spread to other sites by scratching. Infection is spread mainly by the hands, but indirect spread via toys, clothing, equipment and the environment may occur.
Whats the incubation period for impetigo?
Between 4 and 10 days
What is toxic shock syndrome?
Acute disease that is characterised by fever, diarrhoea, nausea, diffuse erythema, shock that is associated with the presence of a bacterium (S. aureus)
What causes toxic shock syndrome?
Staphylococal exotoxins, the TSST-1 superantigen toxin
What are the symptoms of toxic shock syndrome?
Systemic illness with high fever, GI (vomiting, watery diarrhoea), shock and hypotension, severe myalgia, rash
What rash is seen in toxic shock syndrome?
Red mucous membranes and diffuse macular rash; 10 days after infection desquamation of the palms, soles, fingers and toes
What is the diagnostic criteria for staphylococcal TSS?
Temperature over 39 degrees celsius, low systolic blood pressure, rash, involvement of 3 or more organ systems
What are the causative organisms of toxic shock syndrome?
S.aureus or group A streptococcus
What is the treatment for toxic shock syndrome?
IV fluids and resuscitation, abx against staphylococci and streptococci, IV immunoglobulin
What is staphyloccal scalded skin syndrome?
Skin breaks down due to staphyloccus aureus bacteria producing epidermolytic toxins that break down the proteins that hold the skin together
What is the difference in presentation between toxic shock syndrome and scalded skin syndrome?
The latter has less specific systemic manifestations: though still fever, irritability, lethargy. SSS has no involvement from other organ systems
What is nikolsky sign?
Where gentle rubbing of the skin causes it to peel away. No scarring
When is nikolsky’s sign present?
Stevens-Johnson syndrome and scalded skin syndrome
How does scalded syndrome present?
Generalised patches of erythema, skin looks thin and wrinkled. Followed by formation of bullae, which burst and leave sore erythematous skin below
What is the treatment of scalded skin syndrome?
IV flucloxacillin
What bacteria usually keeps candida albicans under control?
Lactobacillus
What are the predisposing factor to thrush?
Moist body folds, treatment with broad spectrum abx, immunosuppression, diabetes
What is the treatment of thrush?
Fluclonazole
What are possible causses of nappy rash?
Irritant dermatitis, candida dermatitis, seborrhoeic dermatitis, psoriasis, atopic eczema
What is the most common cause of nappy rash? Why does it occur?
Irritant dermatitis due to the irritant effect of urinary ammonia and faeces. Creases characteristically spared
What is signs that would indicate candidal infection rather than just simple nappy rash?
Rash extending into skin folds, larger red macules, well demarcated scaly border, satelline lesions (small patches near main leison), circular pattern to the rash spreading outwards
Where does eczema typically present?
Flexor surfaces, with dry, red, itchy sore patchs of skin
What type of virus is HIV?
RNA retrovirus (mostly HIV-1)
What is the basic pathophysiology of HIV?
The virus enters and destroys CD4 T helper cells. Initial seroconversion flu like illness occurs within a few weeks of infection. Then asymptomatic until it progreses and the patient becomes immunocompromised
How is HIV transmitted?
Sexual activity, mother to child (pregnancy, birth, breastfeeding –> vertical transmission), mucous membrane/blood/open wound exposure
How should HIV transmission during birth be prevented?
Via determining viral loads.
<50 copies/ml (normal vaginal delivery), C-section if >50 copies and in all >400 copies/ml. IV zidovudine with c-section if unknown viral load or >10,0000 copies/ml
What prophylaxis treatment can be given to prevent transmission of HIV during birth?
- low risk: zidovudine for 4 weeks
- high risk: zidovudine, lamivudine, nevirapine for 4 weeks
Is breastfeeding ever recommended for mothers with HIV?
No, as it can also be transmitted, even if the viral load is undetectable
When might a child get a false positive result for HIV?
Positive results may be due to maternal antibodies in children aged under 18 months. This does not necessarily mean they are HIV positive
What are the two options for testing HIV?
- HIV antibody screen (can take 3 months to become positive)
- HIV viral load
When are babies to HIV positive parents tested for HIV?
- HIV viral load test at 3 months (if negative, means they have not contracted HIV during birth)
- HIV antibody test at 24 months
What are the key principles of HIV treatment?
- antiretroviral therapy to suppress HIV infection
- normal childhood vaccines
- prophylactic co-trimoxazole for children with low CD4 to protect against pneumocystis jirovecii pneumonia (PCP)
- treatment of opportunistic
What are later features of paediatric HIV infection?
GI: chronic diarrhoea, failure to thrive, CNS: delayed development and cerebral palsy, recurrent bacterial and viral infection, opportunistic infections, respiratory distress: cough, hypoxaemia, bilateral nodule infiltrates on CXR
What opportunistic infections may occur in HIV?
pneumocystis carinii, Candida, herpes virus, varicella, and atypical mycobacteria