ID Flashcards

1
Q

sepsis, septic shock, SIRS definition

A

sepsis

  • organ dysfunction
  • > technically defined by score >2 on SOFA
  • evidence of infection

septic shock

  • criteria for sepsis
  • require fluids and vasopressors to maintain MAP >65
  • lactate >2

SIRS

  • dysregulated inflammatory response
  • can be infectious/non infections
  • defined by 2 or more abnormalities in
  • > temp
  • > heart rate
  • > resp rate
  • > WCC
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2
Q

rheumatic fever pathogenesis

A

Antecedent GAS pharyngitis

  • not associated with other causes of pharyngitis
  • not associated with other GAS infections

Molecular mimicry (pancarditis)

  • M protein
  • > streptococcal antigen
  • > alpha helical coil structure
  • > similar structure to intramyocellular proteins (myosin/tropomyosin)
  • Group A carbohydrate
  • > streptococcal antigen
  • > antibodies to Group A carbohydrate antigen recognise alpha helical coil structure
  • > again, similar to myosin/tropomyosin

Molecular mimicry (chorea)

  • > cross reactive antibodies bind to surface antigen on neurons in brain
  • > calcium/calmodulin dependent kinase II activation
  • > dopamine release
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3
Q

Adenovirus virology and presentations

A

Virology

  • family of viruses
  • > many species subgrouped into serotypes
  • > serotypes have different affinity for body systems
  • transmission
  • > no seasonality
  • > aerosol/fomites/faecal oral
  • > survives on fomites for long periods (non enveloped)
  • > resistant to disinfectant
  • severe illness
  • > associated with several serotypes (eg. 14)
  • > immunocompromised
  • > neonates
  • immunity
  • > serotype specific

Pharyngoconjunctival fever

  • > pharyngitis (may be exudative)
  • > benign conjunctivitis
  • > systemically unwell
  • > may have cervical adenopathy

Epidemic keratoconjunctivitis

  • > bilateral painful corneal opacities
  • > pre-auricular adenopathy
  • > usually self limiting but protracted

Pneumonia

  • > atypical presentation
  • > common and often severe in neonates/infants

Gastroenteritis

  • > common cause of diarrhoea in children
  • Haemorrhagic cystitis
  • > more common in male children
  • > benign and self limited
  • > important ddx for haematuria

Myocarditis
->most common cause of viral myocarditis

Disseminated

  • > occurs in immunocompromised/competent children
  • > can affect almost any organ system
  • > high mortality rate
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4
Q

Enterovirus taxonomy, virology and presentations

A
Family 
->picornavirus
Genus
->enterovirus
Species
->12 enterovirus species
->3 rhinovirus species 
Group (groups of serotypes of one/more species)
-echo
-coxsackie 
-rhino (sub types of the rhinovirus species)
-entero (most recently discovered serotypes)
-polio

Virology

  • unenveloped
  • > resistant to alcohol
  • incidence
  • > highest throughout summer and autumn
  • > highest in infants and males
  • transmission
  • > oral ingestion
  • > predominately faecal or oral secretions
  • > some serotypes from vesicle or respiratory secretions
  • > contaminated food, water and fomites
  • > shed in stool for several months
  • > shed from oropharynx for weeks
  • pathogenesis
  • > ingested
  • > enters lower GI lymphoid tissue
  • > replicates and disseminates
  • immunity
  • > serotype specific

Presentations

  • vast majority of infections = asymptomatic
  • rashes
  • > HFMD/herpangina
  • > generalised maculopapula rash
  • respiratory illnesses
  • > URTI and LRTI
  • CNS
  • > most common cause of aseptic meningitis in infants
  • > polio
  • eyes
  • > acute hemorrhagic conjunctivitis
  • pleurodynia
  • > spasms of chest and abdo wall
  • myocarditis/pericarditis
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5
Q

sepsis investigations (adults and neonates)

A
ECG
Glucose
->hypoglycaemia
Urinalysis 
->leuks and nitrites 
Monitor urine output

Blood culture (before antibiotics)

  • in neonates
  • > preferable peripheral
  • > can be indwelling umbilical or central venous catheter
  • > 1 site is usually sufficient
  • > anaerobic bottle not needed
  • > at least 1mL/bottle
  • in adult
  • > anaerobic and aerobic from 2 different sites
Procalcitonin
->elevated
->helps differentiate SIRS from sepsis
VBG
->acidosis
->hypoxaemia
->hypercapnoea
FBC
->leukocytosis/leukopenia
->immature neutrophils
->thrombocytopenia in DIC
EUCs
->deranged electrolytes
->elevated creatine and urea
LFTs
->deranged
Lactate
-elevated
Coags (if thrombocytopenia)
->prolonged INR/aPPT
->decreased fibrinogen
->elevated D dimer
  • Culture any other foci of infection
  • CXR if suspicion of ARDS

Specific to neonates

  • LP
  • > indicated in all neonates
  • > meningitis often asymptomatic
  • > gram stain/culture/cell count/glucose/protein
  • Urine culture
  • > in late onset neonatal sepsis
  • > if measured in early onset growth = high bacteraemia
  • Tests for fungal and viral infections in neonates
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6
Q

Diagnosis sepsis adult

A

Consider risk factors (absence does not exclude)

  • age > 65
  • immunocompromised
  • recent surgery or wound
  • indwelling device
  • fall
  • representation within 48hrs

Any signs or symptoms of infection

  • altered cognition
  • temperature
  • > fevers
  • > rigors
  • resp
  • > cough
  • > sputum
  • > SOB
  • GI
  • > abdo pain/peritonism
  • > distension
  • urinary
  • > dysuria
  • > frequency
  • in dwelling device
  • > red/swollen/pain

Plus

  • any of following = septic shock/severe sepsis
  • > SBP <90
  • > lactate >4
  • > base excess <5
  • any two of following = possible sepsis
  • > tachypnea/bradypnea
  • > tachycardia/bradycardia
  • > hypothermia/hyperthermia
  • > altered level of consciousness
  • > SPO2 <95%
  • > SBP <100
  • > lactate >2
  • evidence of infection = sign/symptoms
  • organ dysfunction = vitals and investigations
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7
Q

aetiology sepsis unknown source

A

Community:

  • E coli
  • Staph aureus
  • Strep pneumoniae
  • Neisseria meningitidis

Hospital:

  • MRSA
  • Psuedomonas
  • Multidrug resistant gram negative
  • Candida
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8
Q

empirical antibiotics sepsis

A

Community acquired = Gentle Flu

  • gentamycin
  • > 7mg/kg (dose reduce kidney disease)
  • flucloxacilin
  • > 2g

Hospital = Very Miserable Patient

  • Vancomycin (MRSA)
  • > 30mg
  • Meropenam (multi drug resistant gram negative)
  • > 1g
  • Pipercilin + tazobactam (pseudomonas)
  • > 4g + 0.5g

Neonate

  • > 0-2 mnths = 60mg/kg benzylpenicilin + 50mg/kg cefotaxime
  • > > 2months = 50mg/kg cefotaxime + 50mg/kg flucloxacilin
  • no IV access
  • > IM ceftriaxone
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9
Q

antibiotics adult urinary sepsis

A

“Genital antibiotics”

  • Gentamycin
  • > 7mg/kg (dose reduce in kidney disease)
  • Amoxicilin
  • > 2g

both IV

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10
Q

Infectious mononucleosis background

A

Epidemiology

  • more than 90% of adults are seropositive
  • rarely clinical disease in children
  • peak risk in young adult range
  • much more common in caucasians

Aetiology

  • 90% cases EBV
  • > family = herpesviridae
  • > subfamily = gammaherpesviridae
  • > genus = lymphocryptovirus
  • remainder
  • > HHV6 (betaherpesviridae/roseolovirus)
  • > HSV1 (alphaherepesviridae/simplexvirus)
  • > HHV5 (betaherpesviridae/cytomegalovirus)

Pathophys

  • transmission
  • > saliva (median = 6 months post infection)
  • > possibly sexual
  • > possibly breastfeeding
  • infection B cells in oropharynx
  • > circulating B cells infect liver, spleen, lymph nodes
  • > lytic replication
  • incubation period 1-2 months
  • humoral response
  • > viral antigen related antibodies
  • > unrelated antigens (found on horse/sheep RBCs)
  • T cell response
  • > controls initial lytic infection
  • > determines clinical picture
  • latency
  • > viral genome as extrachromosomal episomes
  • > memory B cells
  • > immune avoidance in germinal centres
  • > low level replication
  • neoplasia
  • > immortality of B cell lineages
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11
Q

Infectious mononucleosis diagnosis and management

A

Clinical manifestations

  • classic
  • > fever
  • > fatigue (persistent and severe)
  • > pharyngitis (may be exudative)
  • > tender lymphadenopathy (posterior cervical)
  • additional
  • > systemic (malaise, headache)
  • > palatal petechiae
  • > splenomegaly (splenic rupture)
  • > maculopapular/urticarial/petechial rash (amoxicillin/ampicillin)
  • > neuro (GBS/palsies/meningitis/encephalitis)

Investigations

  • FBC
  • > leukocytosis most common
  • > atypical lymphocytes (10%) on smear
  • > anaemia (haemolytic)/thrombocytopenia rare
  • LFTs
  • > transaminitis
  • heterophile antibody (rapid monospot horse RBC)
  • > confirms diagnosis with compatible syndrome
  • > high false neg in early disease and children
  • EBV specific antibodies
  • > second line (children/protracted/atypical disease)
  • viral capsid antigen IgM (VCA IgM)
  • > detectable = symptom onset
  • > undetectable = 1 month
  • > acute infection/reactivation/CMV infection
  • viral capsid antigen IgG (VCA IgG)
  • > detectable = symptom onset
  • > undetectable = present lifelong
  • > past infection/reactivation
  • early antigens (EA)
  • > detectable = symptom onset
  • > undetectable = 4 months
  • > acute illness/reactivation
  • IgG EBV nuclear antigen (EBNA)
  • > detectable = with latency (2 months)
  • > undetectable = present lifelong
  • > absence supports acute infection
  • imaging
  • > ultrasound spleen = monitoring for return to sport
  • > CT abdo = ?splenic rupture in shocked patient

Management

  • analgesia
  • > paracetamol
  • > NSAIDs
  • rest
  • > no contact sport for 1 month
  • > counsel on effect of fatigue for months
  • IV corticosteroids (severe complications)
  • > upper airway obstruction
  • > haemolytic anaemia/immune thrombocytopenia
  • IgG
  • > severe thrombocytopenia
  • prognosis
  • > resolution within 2 weeks
  • > fatigue may persist for months
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12
Q

Neonatal sepsis diagnosis

A

Clinical manifestations

  • in delivery room
  • > intrapartum tachycardia
  • > meconium staining
  • > low APGARs
  • temperature instability
  • > may be hyper or hypo thermic
  • respiratory signs
  • > distress
  • > apnoea (particularly preterm or GBS)
  • > PPHN
  • cardiovascular
  • > tachycardia (bradycardia in preterm)
  • > hypotension
  • > delayed cap refill/pallor
  • neuro
  • > lethargy
  • > irritability
  • > hypotonia
  • > seizures
  • GI
  • > poor feeding
  • > vomiting/diahorrea
  • > oliguria
  • > jaundice
  • > hepatomegaly

Diagnosis

  • evidence of infection + organ dysfunction
  • > evidence = risk factors
  • > organ dysfunction = clinical signs
  • red flags
  • > any abnormal vitals
  • > fever >38
  • > lactate >2
  • > base excess < -5
  • > procalcitonin >0.5
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13
Q

anaphylaxis criteria

A
Criteria one:
acute onset mucocutaneous symptoms plus
-low BP or its manifestations
or
-respiratory distress
Criteria two:
exposure to possible allergen plus two of
-respiratory distress
-low BP or its manifestations
-mucocutaneous symptoms
-persistant GI symptoms

Criteria three:
exposure to a known allergen plus
-SBP <90 for adults
-BP thresholds for children

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14
Q

anaphylaxis assessment

A
  • exposure to likely allergens
  • > symptoms usually within seconds/minutes
  • > up to approx 4 hours
  • risk factors for fatal anaphylaxis
  • > poorly controlled asthma
  • > pre-existing lung or heart condition
  • > allergy to shellfish, nuts, stings or drugs
  • > alpha and beta blockers/ACEI
  • mucocutanous symptoms (present in 90%)
  • > urticaria
  • > erythema
  • > angioedema
  • respiratory symptoms
  • > stridor/wheeze
  • > persistant cough/sneeze
  • > tightness in throat/choking
  • > change in voice
  • > dysphagia
  • cardiovascular
  • > pale and floppy
  • > syncope
  • > tachycardia
  • > hypotension
  • > throbbing headache
  • > dizziness
  • gastrointestinal
  • > vomiting/diarrhoea
  • > nausea
  • > abdo pain
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15
Q

Post acute care anaphylaxis

A

Treatment

  • consider H2 antihistamines (ranitidine/cimitadine)
  • > itch
  • consider corticosteroids (methyprednisone)
  • > biphasic
  • > limited evidence

Observation

  • at least 4 hours
  • longer if
  • > severe
  • > hx of biphasic
  • > risk factors for fatal anaphylaxis
  • > remote or isolated
  • biphasic reaction
  • > overal risk approx 5% (higher in kids)
  • > up to 3 days later
  • consider tryptase for follow up

Discharge (SAFE)

  • Safety net
  • > recurrence in 20%
  • > patient education
  • > provide anaphylaxis action plan (ASCIA)
  • Allergen avoidance
  • Follow up with immunologist
  • > diagnosis revised in up to a third
  • > confirm allergen
  • > immunotherapy for stinging insects
  • > address co-morbidities
  • Epinephrine
  • > prescribe 2x auto injectors
  • > urge patient to fill immediately
  • > education on proper use
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16
Q

HSV background

A

Epidemiology

  • approx 2/3rds adults are seropositive
  • infection most common in childhood
  • oral herpes
  • > HSV-1
  • genital herpes
  • > predominately HSV-2
  • > HSV-1

Aetiology

  • HSV 1 and 2
  • > family = herpesviridae
  • > subfamily = alphaherpesviridae
  • > genus = simplexvirus
  • HSV-1 spread
  • > oral-oral
  • > oral-genital
  • > vertical (from genital infection)
  • HSV-2 spread
  • > genital-genital
  • > vertical (from genital infection)
  • mode of transmission
  • > asymptomatic/symptomatic viral shedding
  • > greatest risk with active sores
  • > contact with skin, sores, oral/genital fluids

Pathophys

  • primary infection
  • > enters through mucosal surface/skin breaks
  • > replicates in epidermis
  • infects sensory/autonomic nerve ending
  • retrograde axonal transport
  • > infects sensory ganglia
  • latent infection
  • > restricted replication
  • > evades immune destruction
  • > lifelong infection of sacral/trigeminal ganglion
  • reactivation
  • > anterograde axonal transport
  • > lytic replication in epidermis
  • > viral shedding