Paediatric Infectious Diseases Flashcards
Part 1
what is the epidemiology of infectious diseases in children?
- Infection in children is common!!
- Average pre-school child will have 8-12 respiratory tract infections per year
- Majority (in the developed world) due to viruses
- Majority self-limiting (do not need treatment)
- Median duration 8-14 days
- Likely to spend 3-5 months per year with a viral infection
________ in children is a major source of healthcare-seeking behaviour
Large increase in number of admissions and most of the increase is _________ diseases
Signs of infection in children are often very ___________ and can progress quickly and this brings a lot of anxiety to parents
Infection
infectious
non-specific
how has child mortality changed?
it has redued
Primarily through improvements in public health through the provision of clean water, sanitation and hygiene, reducing overcrowding and improving nutrition. But also advances in modern medicine such as antibiotics and immunisations.
why worry about infections?
- Mortality outcomes for C&YP in the UK are considerably worse than comparable high income countries
- The UK ranks in the bottom 3 countries in the EU15+ for mortality from common infections in both sexes and across all age groups
- Mortality from treatable infection in the UK is almost 2x that of our best performing European neighbours
- Infections account for: 16.2% deaths in 1-4 year olds, 8% deaths in 5-9 year olds
•Failure to recognise serious illness at the point of 1st healthcare contact is an important avoidable factor in child death
Part 2
•Severe sepsis is one of the leading causes of death in children
what is the epidemiology in children?
- >½ of all sepsis cases worldwide occurred in children
- Peak incidence in early childhood
- Infants <1y: 1 in 200
- Children 1-4y: 1 in 2000
- Children 5-15y: 1 in 5000
- Case fatality rate ≈10%
- In the UK only 38% compliance with recommended treatment guidelines
- Early recognition and appropriate treatment of sepsis improves survival
what is sepsis?
•Sepsis = SIRS + suspected or proven infection
Overwhelming, life-threatening response to infection which, untreated, can lead to tissue damage organ failure and death
what is severe sepsis?
•Severe Sepsis = Sepsis + organ dysfunction
what is septic shock?
•Septic Shock = Sepsis + CVS dysfunction
traffic light table
what is the recognition tool for sepsis?
Infants <3 months - what are they more at risk of?
- Increased risk bacterial infection
- Increased risk sepsis
- Increased risk meningitis
Infants <3 months - how do they present?
- May have minimal signs & symptoms
- Presentation often non-specific
- May not mount a febrile response (~50%)
- Deteriorate quickly
what increases the risk of infection in Infants <3 months?
- Prematurity (< 37/40)
- PROM
- Maternal pyrexia/chorioamnionitis
- Maternal GBS (this pregnancy)
- Previous child with GBS
- Maternal STI (Chlamydia, Gonorrhoea, Syphilis, HSV)
what is the management of infection?
- Airway
- Breathing
- Circulation – 20ml/kg fluid bolus
- DEFG – ‘don’t ever forget glucose’ – 2ml/kg 10% dextrose
- Antibiotics
- 3rd generation cephalosporin (eg Cefotaxime/Ceftriaxone)
- add IV Amoxicillin if <1m old
what investigations oculd be carried out?
what are the responsible oranisms for infection?
what is the Pathogenesis of Sepsis?
Secretion of pro and anti-inflammatory cytokines
Activation of complement
Activation and mobilisation of leukocytes
Activation of coagulation and inhibition of fibrinolysis
Increased apoptosis
take home messages:
- Sepsis is a major cause of _____ in children
- Early _________ improves survival
- Important to think ‘could this be sepsis?’
- Respond appropriately
- If you’re not sure ask!
- Follow guidelines!
•Paediatricians want to know about any child
death
recognition
3
fever
Part 3
what is meningitis?
• A disease caused by inflammation of the meninges
Meningitis is inflammation of the lining around your brain and spinal cord. It can be very serious if not treated quickly.
3 layers – dura, arachnoid and pia with CSF between your arachnoid and pia mater
Inflammation of underlying brain parenchyma = meningeal encephalitis
what is meningism?
The clinical signs and symptoms suggestive of meningeal irritation
what are the signs and symptoms of meningitis in older children?
- Fever (In older children may see classical triad of fever, headache and neck stiffness)
- Headache
- Photophobia
- Neck stiffness (nuchal rigidity)
- Nausea & vomiting
- Reduced GCS
- Seizures
- Focal neurological deficits
what are the signs and symptoms of meningitis in young infants?
(Infants present with non-specific features)
- Fever or hypothermia
- Poor feeding
- Vomiting
- Lethargy
- Irritability
- Respiratory distress
- Apnoea (pause in breathing lasting at least 20 seconds)
- Bulging fontanelle (signifies raised ICP)
Clinical Signs of Meningitis - what are they?
Nuchal Rigidity (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 are the Causes of Childhood Meningitis
(in the post-vaccine era)?
- Bacterial (4-18%)
- Viral – Mainly Enterovirus (54-88%)
- Fungal – Neonates/Immunocompromised
- Unknown/aseptic (40-76%)
Bacterial Meningitis - what are the responsible organisms for bacterial meningitis in neonates (<1 month) and older infants & children?
H. influenzae meningitis - how have the cases changed?
6.72/100,000 (1992) -> 0.28/100,000 (2008)
decreased
top graph
what is Haemophilus influenzae?
- Small, non-motile, gram-negative coccobacillus
- Nasopharyngeal carriage
- Encapsulated H. influenzae and Non-encapsulated = Non-typeable H. influenzae (NTHI)
Haemophilus influenzae - what do encapsulated and non-encapsulated H. influenzae cause?
•Encapsulated H. influenzae:
- Resist phagocytosis & complement mediated lysis
- 6 serotypes (a-f)
- Hib main cause of invasive H. influenzae infection
- Bacteraemia, Meningitis, Epiglottitis, Pneumonia
- RF – asplenia, sickle cell disease, antibody deficiency
•Non-encapsulated = Non-typeable H. influenzae (NTHI):
- otitis media & sinusitis
- invasive infection rare
what is Neisseria meningitidis?
- Gram negative diplococcus
- Humans only natural hosts
- Nasopharyngeal carriage
- Transmission via respiratory secretions
- Infection often follows viral URTI
- Polysaccharide capsule - capsule composition determines serogroup (eg. A, B, C, W, Y)
- Endotoxin (LPS)
Neisseria meningitidis, often referred to as meningococcus
what ar ethe risk factors for Invasive Meningococcal Disease?
Meningococcal disease is a serious infection caused by the bacteria Neisseria meningitidis. In rare instances, it can become invasive and cause meningitis (an infection of the lining of the brain and spinal cord)
- 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
Invasive Meningococcal Disease - what does it cause?
Huge overlap, features of both
Petechial – small non blanching spots
Purpura – bigger bruise like lesions
Invasive Meningococcal Disease - is it dangerous?
- Rapidly progressive
- Case fatality rate 5-15%
- 50% of deaths in 1st 12h
- 80% of deaths in 1st 48h
•Significant long term sequelae
- Amputation (14%)
- Scarring (48%)
- Hearing Loss
- Cognitive impairment/epilepsy
Going on to look at the third big cause of bacterial meningitis in children:
what is Streptococcus pnuemoniae (Pneumococcus)?
- Gram positive, lancet-shaped, diplococcus
- Facultative anaerobe
- Polysaccharide capsule - inhibits neutrophil phagocytosis, inhibits complement mediated cell lysis
- >90 known serotypes - All serotypes can cause invasive disease
- Colonises nasopharynx (11-93%!)
- Preceeding URTI RF for invasive infection
- Respiratory droplet transmission
Can cause lots of different infections
what are the risk factors for Invasive Pneumococcal Disease?
- Age <2 years
- Cigarette smoking (active or passive)
- Recent viral URTI
- Attendance at childcare
- Cochlear implant
- Sickle cell disease
- Asplenia
- HIV infection
- Nephrotic syndrome
- Immunodeficiency/Immunosuppression
Pneumococcal Meningitis - what can it result in?
- Case fatality in children 8%
- Neurological sequelae common: Hydrocephalus, Neurodisability, Seizures, Hearing loss, Blindness
what is the management of meningitis?
(same as sepsis)
- Airway
- Breathing
- Circulation – 20ml/kg fluid bolus, inotropes
- DEFG – ‘don’t ever forget glucose’ - 2ml/kg 10% dextrose
- Antibiotics
- 3rd generation cephalosporin (e.g. Cefotaxime/Ceftriaxone)
- add IV Amoxicillin if <1m old
what investigations can be done for meningitis?
Blood culture ideally before antibiotics but if not possible then dont delay antibiotics
Lumbar puncture gives you the diagnosis
what are the contraindicaitons of a lumbar puncture?
what do you want to request on a lumbar pucture and what wold your findings be in meningitis?
viral PCR because Viral causes are the most common in children
Bacterial Meningitis - what is the Treatment Duration?
Summary:
- Meningitis remains a serious cause of morbidity and ________ in children
- Bacterial meningitis is a devastating infection with serious long term _______
- Meningitis and sepsis can progress ______
- Early recognition and treatment are _______
- _______ provides effective prevention against many childhood causes of meningitis
mortality
sequelae
rapidly
imperative
Vaccination
Part 4
Majority skin & soft tissue infections caused by what?
by Staph (mainly S. aureus) or Strep (S. pyogenes)
- Both organisms cause osteoarticular infection
- Both organisms cause bacteraemia
- Both cause toxin-mediated diseases - Staphylococcal & Streptococcal Toxic Shock Syndrome (TSS)
what are the micorobiological features of Staphylococcus aureus?
Gram +ve cocci
Coagulase +ve
Produce exotoxins & form superantigens
Colonise skin & mucosa
Resistance is a problem (MRSA)
Staph forms clusters
what are the micorobiological features of Streptococcus pyogenes (GAS)?
Gram +ve cocci
β-haemolytic
Produce exotoxins & form superantigens
Oro-pharyngeal carriage
Resistance is not a problem
(universally S to penicillin)
Staph and strep cause a similar picture of infection, all these pictures could be either
whata re some skin and soft tissue infecitons that they can cause?
what is Staphylococcal Scalded Skin Syndrome?
- Usually <5y
- Toxin mediated (exfoliatoxin)
- Initial bullous lesions
- Followed by widespread desquamation
- Nikolsky sign
- Mild fever
- Purulent conjunctivitis
how is Staphylococcal Scalded Skin Syndrome managed?
Mx – IV Flucloxacillin + IV Fluids
what happens in scalret fever?
Unique to group A strep
Scarlet fever is a toxin mediated disease, you have the acute infection but it is the toxin that produces the rash and things associated with it
how do you manage scarlet fever?
- Notifiable disease - inform public health
- Phenoxymethylpenicillin (Penicillin V) 10 days
- Reduces duration and severity illness by ~1 day
- Reduces incidence of complications (quincy/acute rheumatic fever/post-streptococcal glomerulonephritis)
- Reduces transmission
what are the complications of scarlet fever?
- Abscess formation - retropharyngeal or peritonsillar (quincy)
- Acute Rheumatic Fever - most common cause acquired heart disease in children worldwide, 2-3/52 after pharyngitis, Presents with: arthritis, carditis, chorea, erythema marginatum, subcutaneous nodules
- Post-streptococcal glomerulonephritis
what is Toxic Shock Syndrome (TSS)?
This is the other significant toxin mediated disease
- Acute febrile illness caused by Gram +ve bacteria (S. aureus & GAS) rapidly progressing to shock and multiorgan failure
- Superantigen causes intense T cell stimulation - cessive immune activation, pro-inflammatory cytokine release (TNF-α, IL-1, IL-2, IFN-γ)
- Case fatality - 30-60% GAS, 3-6% S. aureus
what are the clinical features of TSS?
- Fever
- Diffuse, maculopapular, ‘sunburn’ rash
- Mucosal changes - non-purulent conjunctivitis, swollen lips, strawberry tongue
- Profuse diarrhoea (S. aureus)
- Rapid progression to shock & multi-organ failure - tachycardia, prolonged CRT, hypotension, renal impairment, transaminitis, reduced GCS
how is TSS managed?
- ABC
- Fluid resuscitation +/- inotropes
- Cultures - Blood, Throat swabs, Wounds
- IV Antibiotics - Flucloxacillin + Clindamycin
- IVIG
- Avoid NSAIDs
- Surgical debridement
Staphylococcal & Streptococcal Infection
Recap:
- Predominant cause of skin & ____ _______ infection in children
- Cause very similar patterns of _______ - except Scarlet Fever (exclusively GAS) & SSSS
- ______ are major virulence factors
- Can cause significant morbidity and _______
soft tissue
infection
Toxins
mortality
