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
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
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
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
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
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
7
Q
aetiology sepsis unknown source
A
Community:
- E coli
- Staph aureus
- Strep pneumoniae
- Neisseria meningitidis
Hospital:
- MRSA
- Psuedomonas
- Multidrug resistant gram negative
- Candida
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
9
Q
antibiotics adult urinary sepsis
A
“Genital antibiotics”
- Gentamycin
- > 7mg/kg (dose reduce in kidney disease)
- Amoxicilin
- > 2g
both IV
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
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
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
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
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
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
