Paediatric Infectious Disease Flashcards by Jack Pechey

At what age are children most at risk of sepsis?

The younger they are the more at risk of sepsis

1 in 200 children under 1yr get sepsis

Fatality rate is around 10% for children who get sepsis

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What is sepsis?

it’s a systemic inflammatory response syndrome + suspected or proven infection

Sepsis = SIRS + infection

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What are the requirements for a child to be classified as having a systemic inflammatory response syndrome (SIRS)?

Need to have 2 or more of:

Temperature: >38 or <36
WCC: >15x10^9/L or <5x10^9/L
Tachycardia > 2SD above normal for age
Tachpnoea > 2SD above normal for age

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What is severe sepsis? What is septic shock?

Severe sepsis = sepsis + organ dysfunction

Septic shock = sepsis + CVS dysfunction

(Sepsis = SIRS + infection)

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What are some particularly worrying signs that point towards sepsis in children?

Change in skin colour (pale / blue)
Low activity, not responding to social cues, crying
Grunting, tachypnoea, laboured breathing
Tachycardia, reduced cap refill, reduced skin turgor
High temperature, neurological signs, neck stiffness

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What is the paediatric SEPSIS 6?

Temperature: >38 or <36
Inappropriate tachycardia
Poor peripheral perfusion
Altered mental state
Inappropriate tachypnoea
Hypotension

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What are some factors that predispose infants < 3 months to infection (sepsis)?

Prematurity 
Prolonged rupture of membranes 
Maternal pyrexia / chorioamnionitis 
Maternal group B strep 
Previous pregnancy / child with group B strep
Maternal STI

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How do you treat a child with sepsis?

Give high flow oxygen
Take bloods
Give IV antibiotics
Consider fluid resuscitation
Consider inotropic (heart contraction) support

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What fluids do you give to a child experiencing sepsis?

20mL/kg of 0.9% NaCl

2mL/kg of 10% dextrose (don’t ever forget glucose)

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What antibiotics are used to treat a child with sepsis?

3rd generation cephalosporin (cefotaxime)

Add IV amoxycillin if <1 month old

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Which bloods do you want to take for a child with sepsis?

FBC 
CRP
Coagulation screen (DIC)
Blood gas (metabolic acidosis, raised lactate)
Glucose 
Blood culture

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What cultures would you do for an infant suffering from sepsis?

Blood

Urine

CSF

+/- stool depending on history of diarrhoea?

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What are the main organisms causing sepsis in neonates less than one month old?

Group B streptococcus

E. Coli

Listeria Monocytogenes

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What are the main organisms causing sepsis in infants older than 1 month and older children?

Streptococcus pneumoniae

Nisseria Meningitidis

Group A streptococcus

Staphylococcus Aureus

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What are some of the characteristics of staphylococcus aureus?

Gram positive cocci

Coagulase positive (turns fibrinogen - fibrin)

Colonizes skin and mucosa

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What are some of the characteristics of sreptococcus pyogenes?

Gram positive cocci

Beta haemolytic

Colonizes the oropharynx

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what are the majority of skin and soft tissue infections caused by?

Staphylococci and Streptococci

Mostly staph aureus and step pyogenes

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What is staphylococcal scalded skin syndrome? Characteristics?

Condition characterized by initial bullous lesions followed by widespread desquamation (loss of skin)

Severe widespread erythema
Nikolsky sign: press on what seems to be intact skin and it desquamatizes on minimal pressure
Mild fever
Purulent conjunctivitis

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How do you treat staphyloccocal scalded skin syndrome?

IV antibiotics - Flucloxacillin

IV Fluids

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What organism causes scarlet fever? How does scarlet fever tend to present?

Group A Strep (strep pyogenes) (toxin mediated)

At first - fever, malaise, sore throat 
Then:
- Very red "strawberry" tongue 
- Sandpaper erythematous rash 
- Rash isn't on: palms, soles of feet, around mouth

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How is scarlet fever managed?

Notifiable disease - inform public health

10 day course of antibiotics: phenoxymethylpenicillin (penicillin V)

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What are some of the complications of scarlet fever? (incidence reduced by antibiotic use)

Retropharyngeal or peritonsillar abscesses (quincy)
Acute rheumatic fever (most common cause of acquired heart disease in children)
Post-streptococcal glomerulonephritis

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How does acute rheumatic fever present?

Occurs 2/3 weeks after pharyngitis
Arthritis
Carditis
Chorea (involuntary, unpredictable movements)
Erythema marginatum
Subcutaneous nodules

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What is the causative organism for toxic shock syndrome? How severe is this condition? What is the mechanism of the condition?

Caused by gram positive bacteria (S aureus and group A strep)(fatality much higher with GAS)

Very severe - can rapidly progress to shock and multiorgan failure

Superantigen causes intense T cell stimulation: excessive immune activation and pro-inflammatory cytokine release

What is group A strep?

Streptococcus pyogenes

What is the initial presentation of toxic shock syndrome?

- Non-purulent conjunctivitis - Swollen lips - Strawberry tongue - Diffuse, maculopapular "sunburn" rash - If S. Aureus: severe diarrhoea

What are some signs that toxic shock syndrome is progressing?

- Tachycardia - Prolonged Capillary refill - Hypotension (more rapid onset than usual) - Reduced GCS - Renal impairment - Transaminitis (high liver enzymes)

Investigations for toxic shock syndrome?

Cultures: - Bloods - Throat swabs - Wounds

Management of toxic shock syndrome (TSS)?

- Give oxygen and take bloods - Fluid resuscitation (.9% NaCl & 10% dextrose) - IV antibiotics: flucloxacillin and clindamycin - IV immunoglobulins (IVIG) Avoid NSAIDS (can cause necrotizing fasciitis)

What is one very important step in the management of toxic shock syndrome?

Surgical debridement: if there are any areas of pus remaining there is still ongoing toxin production and inflammatory response

What is meningitis? What is meningism?

Meningitis - A disease caused by the inflammation of the meninges Meningism - the clinical signs and symptoms suggestive of meningeal irritation

How do older children with meningitis tend to present?

- Fever - Headache - Photophobia - Neck stiffness Nausea and vomiting Reduced GCS Seizures Focal neurological deficits

How do young infants tend to present with meningitis?

- Fever or hypothermia - Poor feeding & vomiting - Lethargy, irritability - Respiratory distress - Apnoea - Bulging fontanelles

What is apnoea?

Temporary cessations in breathing

What are some clinical signs of meningitis?

- Neck stiffness: palpable resistance to neck flexion - Brudzinski's sign: hips and knees flex on passive flexion of the neck - Kernig's sign: pain on passive extension of the knee

What is the most common cause of childhood meningitis?

Viral - mainly enterovirus

What causes childhood meningitis?

Bacterial 4 - 18% Viral 54 - 88% Unknown / aseptic 40 - 76% Fungal neonates / immunocompromised

What organisms are responsible for causing bacterial meningitis in young infants?

Group B Strep (strep agalactiae) E. Coli Listeria monocytogenes

What organisms are responsible for causing bacterial meningitis in older children?

Strep pneumoniae Nisseria meningitidis Haemophilus influenzae type B (Hib)

What condition does non-encapsulated haemophilus influenzae cause commonly?

Otitis media | & sinusitis

What are some characteristics of nisseria meningitidis?

Gram negative diplococcus Nasopharyngeal carriage Invasive infection often follows viral URTI

What are some risk factors for invasive meningococcal disease?

``` Age (< 1 year or 15-24 years) Unimmunised Crowded living conditions Household or kissing contact Cigarette smoking (active or passive) Recent viral / mycoplasma infection Complement deficiency ```

What is the cardinal sign of meningococcal meningitis?

Petechial and more so purpuric rash - Petechiae: small red / purple non-blanching spots on skin - purpura: bigger red / purple rashes

How severe of a disease is invasive meningococcal disease?

Severe: - Rapidly progressive - Case fatality of 5-15% - 50% of deaths in first 12h, 80% in 48h - Significant long term complications: amputation (14%), scarring (48%), hearing loss, cognitive impairment / epilepsy

What organism causes meningococcal meningitis / meningococcal disease?

Nisseria meningitidis

What are the characteristics of streptococcus pneumoniae?

Gram positive > 90 serotypes, all can cause invasive disease colonizes the nasopharynx Invasive infection commonly preceded by URTI

Why is it hard to vaccinate against strep pneumoniae?

Because there are so many serotypes and as you vaccinate one a higher proportion of cases becomes composed of other serotypes

What are some risk factors for pneumococcal disease?

``` Age (< 2 years) Cigarette smoking (active / passive) Recent viral URTI Attendance at childcare Cochlear implant Sickle cell disease Asplenia (bad spleen function) HIV infection Nephrotic syndrome Immunodeficiency / immunosuppression ```

Main big risk factors for bacterial meningitis?

preceding URTI Age < 1 or 2 Exposure to lots of people Cigarette smoking

What are some common complications of pneumococcal meningitis?

Neurological consequences are common: - Hydrocephalus - Neurodisability - Seizures - Hearing loss - Blindness

How do you treat meningitis?

Same as sepsis: - Give oxygen and take bloods - Fluid resuscitation (.9% Nacl & 10% dextrose) - Antibiotics: 3rd gen cephalosporins (cefoxatime) as well as IV amoxycillin if <1 month old)

What are the two main investigations for meningitis in children?

Bloods Lumbar puncture*** (diagnostic)

What bloods are done for children with suspected meningitis?

``` FBC U&E's / LFTs CRP Coagulation screen Blood gas Glucose Blood culture **** (ideally before antibiotics but don't delay) Meningococcal / pneumoccocal PCR ```

What are the main contraindications to lumbar puncture?

Signs of raised ICP: - GCS<9, abnormal tone / posture, high BP & bradycardia, pupillary defects, papilloedema) - Focal neurological signs - Recent seizure - Cardiovascular instability - Coagulopathy - Thrombocytopenia - Extensive or extending purpura

What do you send the CSF for once you've done your lumbar puncture?

``` Microscopy Gram stain Culture Protein Glucose Viral PCR ******* (most common cause of meningitis) ```

What findings are expected from the CSF after a lumbar puncture if bacterial meningitis?

Turbid or purulent CSF appearance High opening pressure when doing LP High CSF WCC (neutrophils) High Protein in CSF Low glucose in CSF

What findings are expected from the CSF after a lumbar puncture if viral meningitis?

Clear appearance Protein mildly raised or normal WCC very high (lymphocytes) Glucose unchanged

What accounts for the differences between viral and bacterial CSF findings?

- 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

Most common causes of viral meningitis?

herpes simplex virus (HSV), enterovirus varicella zoster virus (VZV)