Infectious Diseases Flashcards by Katie Robertson

What is sepsis?

SIRS +suspected or proven infection

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What is severe sepsis and what is septic shock?

Severe sepsis=sepsis + organ dysfunction

Septic shock=sepsis + CVS dysfunction

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What >2 of categories is needed for SIRS to be present?

Temp
WCC
Tachycardia
Tachypnoea

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Why should you not focus too much on looking for hypotension in paediatrics when it comes to sepsis?

Incredibly late sign in children and only drop BP when in decompensated shock

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Why do we worry specifically about infants <3 months in age?

Increased risk of bacterial infection, sepsis, meningitis
May have minimal signs and symptoms
Presentation often non-specific
May not mount a febrile response
Deteriorate quickly

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What risk factors would make you think of infection in an infant <3 months?

Prematurity (<37/40)
PROM
Maternal pyrexia/chorioamnionitis
Maternal GBS or previous child with GBS
Maternal STI

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What is the management of sepsis?

ABC (C=fluid bolus (20ml/kg 0.9%NaCl)

DEFG (Don’t ever forget Glc)=2ml/kg 10% dextrose

Abx:
- 3rd generation cephalosporin (e.g. Cefotaxime/Ceftriaxone)
- Add IV amoxicillin if <1month old (Listeria not covered - most common cause of sepsis meningitis in this age)

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What bloods are done in sepsis?

FBC (leukocytosis, thrombocytopaenia)

CRP

Coagulation screen (DIC)

Blood gas (metabolic acidosis, raised lactate)-capillary or venous

Glc

Blood culture

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What cultures are taken in sepsis?

Blood
Urine
CSF (including send to virology)
+/-stool (micro + virology)

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If a child is presenting with sepsis with an unclear source what can a CXR be helpful for excluding?

Focal Pneumonia

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What different organisms are responsible for sepsis in neonates <1 month compared to older infants & children?

Neonates:
- Group B strep
- E.coli
- Listeria monocytogenes

Older infants & children:
- Strep pneumoniae
- Neisseria meningitidis
- Group A strep
- Staph aureus

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If any child <3 months with … unless its immediately post immunisation paediatricians want to see them

FEVER

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What is meningitis and what is meningism?

Meningitis=A disease caused by inflam of the meninges

Meningism=The clinical signs & symptoms suggestive of meningeal irritation

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Where does CSF lie?

Between arachnoid and pia mater

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What is apnoea?

Pause in breathing lasting for >20 secs-unique to young infants

Sign of significant respiratory distress and reduced resp drive

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What are the clinical signs of meningitis?

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

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What are the causes of childhood meningitis?

Bacterial
Viral (mainly enterovirus)
Fungal-neonates/immunocompromised
Unknown/aseptic

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What are the organisms cause bacterial meningitis?

Neonates (<1month)
- Group B strep
- E.coli
- Listeria

Older infants and children
- Strep pneumoniae
- Neisseria meningitidis
- Hemophilus influenzae type B (HiB)

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How is H. Influenza carried and what is the type should be worried about?

Nasopharyngeal carriage

Small, non motile, gram -ve coccobacillus

Encapsulated H. influenza

(Non encapsulated=non typable H.influenzae (NTHI)-otitis media & sinusitis-rare for it to cause invasive infection)

Neisseria meningitidis is a gram -ve diplococcus in which humans are its only natural hosts. How is it transmitted?

Nasopharyngeal carriage
- Transmission via resp secretions
- Infection often follows viral URTI
- Polysaccharide capsule

Endotoxin (LPS)-big driver of the sepsis response

What are the 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

Invasive meningococcal disease is rapidly progressive, what are some significant long term sequelae associated with it?

Amputation

Scarring

Hearing loss

Cognitive impairment/epilepsy

Streptococcus pneumoniae (Pneumococcus)-Gram +ve lancet shaped diplococcus, facultative anaerobe, polysaccharide capsule: where dose it colonise?

Colonises nasopharynx

Preceding URTI RF for invasive infection

Resp droplet transmission

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

What are the common neurological sequelae of pneumococcal meningitis?

- Hydrocephalus - Neurodisability - Seizures - Hearing loss - Blindness

What is the treatment of meningitis?

SAME TX AS SEPSIS!!!! ABC DEFG Abx

What bloods should be done for meningitis?

FBC (leukocytosis, thrombocytopaenia) U&Es, LFTs CRP Coagulation screen (DIC) Blood gas (metabolic acidosis, raised lactate) Glucose Blood culture Meningococcal/Pneumococcal PCR

LP is essential in meningitis when should it ideally be done?

Ideally prior to Abx but do not delay Abx if LP cannot be performed

When should you definitely not do a LP?

When there are signs of raised ICP

What should you request on an LP?

Microscopy Gram Stain Culture Protein Glucose Viral PCR

What are the findings on LP of a bacterial meningitis?

- Turbid or purulent - High opening pressure - WCC increased (polymorphs) - High protein - Reduced Glc (<50% serum)-should do a blood sugar at the same time as doing LP

Are different organisms that cause bacterial meningitis treated for different durations?

They are indeedy

Majority of skin & soft tissue conditions are caused by what and what can both these organisms cause?

Staph (mainly S. aureus) or Strep (S. pyogenes) Both organisms cause osteoarticular infection, bacteraemia, toxin-mediated diseases (Staphylococcal & Streptococcal Toxic Shock Syndrome (TSS)) Can be difficult to distinguish clinically

Is resistance a problem in Strep pyogenes?

Strep is universally S to penicillin

Strep is B haemolytic and has oropharyngeal carriage whereas staph aureus is?

Coagulase +ve and colonises skin and mucosa

How does staphylococcal scalded skin syndrome present?

- Usually <5yo - Toxin mediated (exfoliatoxin) - Initial bullous lesions - Followed by widespread desquamation - Mild fever - Purulent conjunctivitis

What sign is indicated in staphylococcal scalded skin syndrome and how is the condition managed?

Nikolsky sign (rub over skin-sloughs off, desquamates under minimal pressure) Mx=IV Flucloxacillin + IV fluids

What are the characteristics of scarlet fever (scarlatina)?

- 2-5 day incubation period - Fever, malaise, sore throat - STRAWBERRY TONGUE - SANDPAPER RASH - Skin peeling (desquamation)

How is scarlet fever managed?

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 potential 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 - arthritis, carditis, chorea, erythema marginatum, subcutaneous nodules Post-streptococcal glomerulonephritis

What is toxic shock syndrome (TSS) and what can it result in?

Acute febrile illness caused by Gram +ve bacteria (S. aureus & GAS) rapidly progressing to shock and multiorgan failure Superantigen causes intense T cell stimulation excessive 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 (increases risk of necrotising fasciitis) Surgical debridement

Staph and strep cause very similar patterns of infection except in what?

Except Scarlet Fever (exclusively GAS) & SSSS

Toxins are major ... factors of staph and strep

VIRULENCE

What organism is scarlet fever unique to?

GROUP A STREP (GAS)

What are the predominant causes of skin & soft tissue infection?

Staph & strep infections