Micro Flashcards
1
Q
Adult onset Still’s disease and MAS
A
Very high ferritin
2
Q
EBV Serology
A
PCR is pointless in healthy person
Viral Capsid Antigen (VCA) - with symptoms
EP Nucleic Antibody (EBNA) - later
3
Q
Bartonella
A
Cat scratch illness, regional adenopathy, sometimes PUO
Sometimes HSM and haem abnormalities.
Diagnosis by serology
4
Q
Brucella
A
Must have exposure (farm animal contact or unpasteurised milk)
LFTs rise. Diagnosis by serology.
5
Q
PET CT
A
All activated leukocytes demonstrate increased FDG uptake
6
Q
IGRA
A
Test for latent TB
7
Q
TTE (transthoracic echocardiogram)
A
Useful in IE
5-10% have negative BCs because of abx or Fastidious organisms (HACEK) or Aspergillus, Bartonella, Brucella, Coxiella, Rickettsia, Mycobacteria, Nocardia, Chlamydia
(IV drug user may take abx themselves and not tell you – linezolid)
8
Q
HACEK
A
Haemophilus, Aggregatibacter
Cardiovacterium
Eikenelia
Kingella
9
Q
Dukes Criteria
A
2 major or 1 major + 3 minor criteria
Major
Persistent bacteraemia (>2 BC pos)
Echocardiogram: vegetation
Positive serology for Bartonella, Coxiella or Brucella
Minor Predisposition (murmur, IVDU) Inflammatory markers (fever , CRP high) Immune complexes: splinters, RBCs in urine Embolic phenomena: Janeway lesions, CVA Atypical echo 1 positive BC
10
Q
Giant Cell arteritis
A
>50y Jaw claudication Headache ESR >45 High risk of sight impairment / stroke Temporal biopsy gold standard
11
Q
Adult onset Stills disease
A
Salmon pink rash (macular papular)
Very high ferritin
12
Q
Which of the following malignancies is least likely to be associated with fevers
Lymphoma Renal cell carcinoma Leukaemia Hepatocellular carcinoma Adenocarcinoma of the lung
A
Adenocarcinoma of the lung
13
Q
African tick bite fever
A
Ricketssia
14
Q
Lyme disease, ticks
A
Borrelia
15
Q
Cyclist, Richmond, insect bite
A
Borrelia Lyme disease (tick bites)
16
Q
safari, TseTse fly, Winterbottom’s sign
A
Trypanosoma brucei
- sleeping sickness
17
Q
Goat, Unpasteurized milk, back pain + discitis
A
Brucellosis
18
Q
Comma, oxidase +ve, bloody foul diarrhoea, a/w Guillain-Barre, Reiters
A
Campylobacter
19
Q
Slow onset fever, constipation, bradycarida, splenomegaly, rose spots
A
Salmonella typhi or paratyphi
20
Q
Non-bloody diarrhoea, poultry/eggs/meat
A
Salmonella enteritedes
21
Q
Bartonella henselae – cat scratch disease
A
Macule at site of innoculation
Becomes pustular
Regional adenopathy
Progress to systemic symptoms in 14%
Mx: erythromycin, doxycycline
22
Q
Bartonella henselae – bacillary angiomatosis
A
Occurs in immunocompromised - HIV
Skin papules
Disseminated multi-organ and vasculature involvement
Mx: Erythromycin, Doxycycline PLUS rifampicin
23
Q
Cats/ undercooked meat, obligate intracellular parasite
A
Toxoplasmosis (T. gondii)
24
Q
toxoplasmosis features
A
Fever Adenopathy Still-birth Progressive visual, hearing, motor, & cognitive issues Seizures (immunocompromised) Neuropathies (immunocompromised)
25
toxoplasmosis management
Spiramycin
| Pyrimethamine plus sulfadiazine – don’t give to pregnant woman – treatment for immunosupressed head toxo
26
anti-O-polysaccharide Ab, normal WCC
Brucellosis
27
Brucellosis treatment
Doxycycline PLUS
| Gentamicin OR Rifampicin
28
Back pain, undulant fever (peaks in evening), focal abscess (psoas)
Brucellosis
29
Rhabdo virus, warm blooded animals, Negri bodies, fatal encephalitis
Rabies
30
Fever, polyarthralgia, maculopapular rash becomes purpuric, may progress to endocarditis, transmitted by rats
Rat bite fever
Spirillosis or streptobacillosis
mx: penicillin
31
Natural reservoir of influenza A viruses
Ducks
32
Influenza virus infection causes respiratory disease because
influenza virus requires activation by host cell proteases that are only expressed in the respiratory tract
Haemagglutinin must be cleaved in two in order for fusion event (release genome) to take place
Requires human airway tryptase
Some avian viruses have mutations which allow them to be cleaved in any part of the body = very pathogenic
33
Binds sialic acis on host cell allowing entry of virus
Haemagluttinin
34
Cleaves sialic acid residues, exposes host cell receptors, disrupts mucin barrier
Neuroaminidase
35
Gene in all human influenza viruses
PB2 627K
36
Avian virus gene
PB2 627E
37
Human H5N1 and H7N9 (avian flu) infections associated with severe disease gene mutation
PB2 E627K mutation - allows avian virus to infect humans
| Lysine residue in a PB2 gene = hallmark
38
Features of HA and NA that affect influenza transmission
Receptor binding - HA adapted to binding
Virion stability - HA adapted to fusion at lower pH (mucus is acidic)
NA stalk length
39
Swine flu
pH1N1
| similar to H1N1 in 1920 - people alive at this time were relatively protected
40
severe outcomes from pH1N1
High dose, route of exposure
Mutant virus (D225G mutation)
Bacterial superinfection
Co morbidity: Asthma, pregnancy, obesity, diabetes
Genetic predisposition: IFITM3 mutation; ethnic bias
41
IFITM3
Gene normally protective against viral infection
Loss = increase susceptibility
Higher prevalence in China and Japan
42
Antiviral for flu - Targets M2 ion channel
Amantadine – old fashioned drug
Single amino acid mutation in M2 (S31N) renders virus resistant
Does not work against influenza B or pH1N1 or seasonal H3N2
43
Antiviral for flu - Neuraminidase inhibitors
Tamiflu (oseltamivir) oral – largely available in UK
Relenza (zanamivir) inhaled or iv formulation
Peramivir iv
44
Antiviral for flu - Polymerase inhibitors
Favipiravir (licensed in Japan excluding pregnant women - teratogenic)
Baloxavir (licensed in Japan)
Currently license in Japan (particularly in pandemic)
45
Seasonal Influenza vaccine
A purified fraction containing HA and NA of an inactivated virus
Given to at risk groups
Short term strain specific immunity
46
Seasonal Influenza vaccine - children
Live attenuated vaccine, also tri or quadrivalent
Cold adapted virus limited to URT (sprayed up nose)
Broader immunity including cellular response
47
Malaria - P. Falciparum
Length of rhythm - 48h (tertian)
| Blood film = young trophozites (rings), crescent-shaped gametocytes
48
Malaria - P. Vivax
Length of rhythm - 48h
Chronic liver stage (hypnozites)
Blood film = Schuffners dots, >20 merozites/ schizont
49
Malaria - P. Ovale
Length of rhythm - 48h
Chronic liver stage (hypnozites)
Blood film = Schuffners dots
50
Malaria - P. Malariae
Length of rhythm - 72h (quartan)
Benign
Similar morphology to P. Knowlesi
51
Malaria - P. Knowlesi
Behaves like falciparum
Increasing incidence in SE Asia
1-2 cases/year UK
52
Malaria treatment - non-falciparum
Chloroquine (3d)
Primaquine (14 days) - for liver stage
Complications - rare (splenic rupture = fatal)
53
Malaria treatment - falciparum
Mild: oral
First line = Malarone (Atovoquone/ Proguanil)
Severe (>2% parasitaemia)
IV Artesunate
54
Dengue Fever
Vector - Aedes mosquito
Flavivirus
Short incubation, urban disease
Usually mild/ self limiting - fever, rash, arthralgia
Already infected with different serotype = increased risk of dengue haemorrhagic fever and shock (bleeding, complications)
Tx - supportive, no specific antiviral tx
55
Typhoid
Salmonella Typhi or Paratyphi
56
Typhoid Clinical features
```
Insidious onset (incubation 7-18d)
High, prolonged fever
Headache
Rose spots (minority)
Constipation
Complications - GI bleeding, perforation, encephalopathy
```
57
Typhoid Tx
```
Empiric ceftriaxone (2g IV OD)
Azithromycin (500mg BD 7days)
```
58
Mononucleosis
```
EBV, CMV
Tonsillar enlargement with exudates
atypical lymphocytosis
monospot
IgM + EBV/CMV
```
59
Ricketssial Disease
obligate intracellular bacteria
fever, headache, myalgia +/- eschar
vectors - ticks/ lice/ mites
tx - doxyxycline
60
Entameoba Histolytica
```
MSM
food, water, soil
motile trophozite in stool - 4 nuclei
flask-shaped ulcer
dysentery, wind, tenesmus
wt loss RUQ pain (liver anscess)
tx: metronidazole
```
61
Giardia lamblia
travellers/hikers/MSM/mental hospitals
pear shaped trophozite in stool - 2 nuclei
malabsorption - foul-smelling non-bloody diarrhoea
ELISA string test
tx: metronidazole
62
Cryptosporidium parvum
```
jejunum
severe diarrhoea
immunocompromised
oocytes in stool
tx: paromomycin
```
63
Kinyoun acid fast stain
tests for oocytes in stool in Cryptosporidium parvum
64
Katayama fever
acute schistosomiasis
| eosinophilia a/w invasive helminth
65
Cholera toxin mechanism (secretory diarrhoea)
cAMP opens Cl- channel on enterocytes
| Efflux Cl to lumen; loss of H20 and electrolytes
66
Superantigens mechanism (diarrhoea)
Directly bind T cell receptors and MHC molecules
Outside peptide binding site
>> massive cytokine production (CD4+)
Systemic toxicity and suppression of adaptive immune response
67
S. Aureus food poisoning
```
Shed via skin into food
Virulence factor - Protein A
Catalase, coagulase +ve, clusters
Beta haemolytic
Vomiting, watery diarrhoea, non-bloody diarrhoea
Tx: self limiting
```
68
Bacillius cereus
```
reheated rice - spores
superantigen
short incubation period - 4hrs
watery non bloody diarrhoea
Tx: self limiting
```
69
Clostridia Botulinum
Canned food - honey in children, beans in students
Blocks Ach release - descending paralysis (botulinism)
Tx: antitoxin
70
Clostridia Perfringens (food poisoning)
reheated food/ meat
enterotoxin/ super antigen acts on small bowel
incubation 8-16h
watery diarrhoea, cramps, little vomiting (lasts 24h)
prolonged - gas gangrene - gut necrosis?
71
Clostridia Difficile
anaerobe
abx related colitis (cephalosporins/ fluorquinolones)
pseudomembrnaous colitis
Tx: metronidazole (stop causative abx)
72
Listeria monocytogenes
```
febrile gastroenteritis
Beta haemolyitc
Aesculin positive with tumbling motility
refrigerated food/ unpasteurised dairy/ veg
perinatal infection, immunocompromised
Tx: ampicillin
```
73
ETEC
toxigenic
| travellers diarrhoea
74
EIEC
invasive dysentary
75
EHEC
haemorrhagic
O157:H7 shiga-like verocytotoxin causes HUS
petting zoo - very unwell (ICU)
76
EPEC
infantile diarrhoea (P for paeds)
77
Shigella
distal ileum and colon
Inflammation, fever pain, bloody diarrhoea
Shiga enterotoxin
78
Yersinia enterocolitis
Mesenteric adenitis w necrotising granulomas
A/w reactive arthritis and erythema nodosum
Food contaminated w domestic animal excreta
79
Virbriosis Cholera
rice water stool
cAMP binds Cl channels - increas Cl in lumen (loos H20/ electrolytes)
massive diarrhoea without inflammation
supportive tx
80
Vibriosis Parahaemolyticus
```
Ingestion of raw undercooked seafood (Japan)
3/7 diarrhoea
self limiting
salty agar
tx: doxycycline
```
81
Vibriosis vulnificus
cellulitis in shellfish handlers
tx: doxycycline
HIV - fatal septicaemia w D+V
82
Campylobacter jejuni
```
curved/comma/ S shaped
unpasteurised milk, food eg poultry
bloody foul smelling diarrhoea
prodrome: headache fever, cramps
oxidase +ve, motile, sensitive to nalidixic acid
```
A/w Guillain-Barre, reactive arthritis (Reiter's)
83
Listeria
watery diarrhoea, little vomiting
perinatal infection, immunocompromised
febrile gastroeneteritis (outbreaks)
unpasteurised dairy, refrigerated food, vegetables
84
Norovirus
adult outbreaks
| vomiting
85
Rotavirus
dsRNA "wheel like"
<6yrs
secretory, diarrhoea no inflammation
watery diarrhoea by stimulation of eneteric nervous system
exposure to natural infection twice = life long immunity
86
Adenovirus
types 40, 41
| cause non bloody diarrhoea in <2yrs
87
Sporadic CJD
80%
Somatic PRNP mutation or spontaneous conversion
Rapid progressive dementia (myocoluns, cortical blindness, LMN signs)
45-75y
Survival - 6m
88
Sporadic CJD Investigations
EEG - periodic triphasic changes
MRI - Highlighting basal ganglia (may be normal)
14-3-3 protein +ve
129 codon MM (most)
Post mortem - spongiform vacuolation, PrP amyloid plaques
89
Variant CJD
Acquired - exposure to Bovine Spongiform Encephalitis
Anxiety/paranoia/hallucinations + neuro symptoms
later - chorea, ataxia, dementia
30yrs
Survival - 14m
90
Variant CJD Investigations
EEG - non specific slow waves
MRI - posterior thalamus (pulvinar sign)
129 codon MM (all)
Post mortem - PrPsc 4t detectable in CNS, florid plaques
91
Iatrogenic CJD
Inoculation - surgery
Progressive ataxia
Later - dementia and myoclonus
Progression - depends on route of inoculation (CNS - fastest)
92
Kuru CJD
Acquired CJD
Cannibalism
Progressive cerebellar syndrome
Death within 2y
93
Gerstmann Straussler-Scheinker Syndrome
```
Inherited CJD
Autosomal dominant
20-60y
Survival - 5y
Dysarthia - progresses to cerebellar ataxia (+ dementia)
```
94
Fatal Familial Insomnia
```
Inherited CJD
Inherited CJD
Autosomal dominant
Insomnia + paranoia - hallucinations + wt loss
Mute
Survival 1-18m
```
95
Inherited CJD investigations
MRI - high signal in basal ganglia
| 129 codon homozygosity - earlier onset
