Rando Infections and Derm Flashcards
to be like catriona
What are the 4 most common bacterial causes of diarrhoea
C difficile
Salmonella
Shigella
E coli O517
Two viral causes of diarrhoea
Rotovirus
Norovirus (umbrella term)
3 most common parasitic causes of diarrhoea
amoebic dysentery caused by entamoeba histolytica
giardiasis caused by giardia
cryptosporidium
E coli obtained whilst travelling is more or less serious
more
How does cholera work?
There is a toxin that draws fluid into lumen, as it opens up C amp channels that causes loss of chloride, therefore loss of sodium, therefore loss of water.
How do we treat cholera?Why don’t we give antibiotics in cholera?
just oral/IV fluids
NB for oral if you give glucose as well as salt in the water, better result.
Because it destroys therefore releases more of the toxins into the blood stream
What are the 4 C’s we avoid to prevent C difficile?
clindamycin
cephalosporins
co-amoxiclav
ciprofloxacin
Which endocrine condition could cause diarrhoea?
Hyperthyroidism
What investigations when diarrhoea?
Stool sample- obvious reasons
Full blood count- for inflammation markers
Abdominal X-ray or CT if abdomen distended (for toxic dilatation)
anti-alpha gliadin antibodies in blood test (serum) for coeliac disease
Thyroid function test (blood test)
Diarrhoea with no abdominal pain or tenderness is less likely to be gastroenteritis, and more likely to be?
sepsis
Complication of E.Coli O157?
haemolytic-uraemic syndrome, where bacterial toxins enter bloodstream and destroys red blood cells and damages blood vessels, and also glomeruli becomes clogged with platelets.
haemolytic-uraemic syndrome usually seen how
in children after diarrhoea, they become PALE and have less energy, may be irritable.
Incubation and duration of symptoms for campy jejuni (travellers)
2-5,
resolves in 3-6
What antibiotics for campy jejuni (if severe risk factors like heart failure or HIV)
clarithromycin (because for gram positive)
Treatment of severe shigella, which can lead to haemolytic uraemic syndrome?
ciprofloxacin (broader range)
Where do we see cysts in giardiasis?
Cysts are released into the faeces
giardiasis- diagnosed through stool. Treated how?
tinidazole or metronidazole
After salmonella, what complication may occur a few months later?
IBS symptoms
what cells does the hiv virus destroy
CD4 T-helper cells
A seroconversion illness occurs after a new HIV infection. What do I mean by this?
Antibodies are being produced. A flu-like illness occurs for a few weeks, then the patient is asymptomatic- until you reach immunodeficiency.
Why can’t you catch HIV through kissing?
Because there are antibodies and enzymes found naturally present in saliva that prevents HIV infecting new cells.
AIDs defining illness occurs when the CD4 count drops to what level?
200 cells /mm^3.
What’s a normal CD4 count?
500-1500 cells/mm^3
Testing for HIV RNA per mil is testing for what?
viral load. undetectable = 20 copies or below. Serious HIV can be hundreds of thousands.
How do we treat HIV?
combination of antiretroviral medications (e.g. protease inhibitors- don’t cure, but does block ability of HIV to function).
What viral load/copies means you would do a C section to try prevent transmission during birth?
Over 50 copies (def when 400 or over according to guidelines)
IV ‘‘x’’ is given as an infusion during labour and delivery if the viral load is unknown or above 1000 copies/ml.
Prophylaxis may be given to the baby, depending on the mother’s viral load:
Low-risk babies (mother’s viral load is under 50 copies per ml) are given ‘‘x’’ for 2-4 weeks
What’s x?
zidovudine
How does zidovudine work?
It incorporates itself into the viral DNA
Why might statins be recommended in HIV?
Because there is increased risk of cardiovascular disease
How quickly can post exposure prophylaxis be used?
Less than 72 hours.
What are pyrogens?
substances that cause fever.
What do I mean when i say pyrogens can be exogenous?
‘from outside’ e.g. endotoxins of gram negative bacteria.
Pyrogens can be exogenous, or can be endogenous: give example of endogenous?
Cytokines released from host cells in response to infection
How do pyrogens act?
1) Causing elevation of the set point of the hypothalamic regulatory centre, which in turn results in:
2) vasoconstriction and decreased peripheral heat loss.
what’s the hypothalamic regulatory centre
The thermostat of the hypothalamus, where the brain controls the heating
Definition of pyrexia of unknown origin?
temperature of greater than 38.3’c , on multiple occasions, for greater than 3 weeks.
whats nosocomial PUO ?
fever which develops in hospital and is undiagnosed after 3 days of investigation, including 2 days of culture
What’s neutropenic PUO?
Fever in a patient with a neutrophil count up to 500 cells /mm^3, which is undiagnosed after 3 days of investigation.
What’s HIV associated PUO?
Fever in a patient with HIV infection, which has been present and undiagnosed for more than 3 days in an inpatient or 4 weeks in an outpatient
What investigation is mandatory in a patient with PUO?
complete physical examination (repeated could be fruitful)
What is it, that a patient with endocarditis, could develop that may appear on examination?
a murmur
why would the physical examination for someone with PUO, include examination of the fingernails?
splinter haemorrhages in endocarditis
4 main areas of cause of PUO?
infections, tumour disease, inflammatory disease, cardiovascular conditions
and fifth = undiagnosed (about 1/4 of patients)
why would you offer a HIV test to a PUO patient
its a cause
Taking a good history is important. People can present with benign relapsing malarias how many years late?
maybe up to ten years after leaving an endemic area
Why is occupation/social history important in PUO cases?
people can get febrile reactions to exposure to certain chemicals
Why take a family history in Puo?
for ‘pattern of fever’ => familial causes maybe
With puo, why lymphadenopathy?
malignancies is a cause
With puo, why chest x ray?
for malignancy or tb
Blood cultures are a mainstay of investigating febrile patients. When do you do that?
taken at time of fever, at least 3 sets of cultures
if headache with puo, what should you do?
do a temporal artery biopsy
Is staph aureus gram positive or negative
gram positive
How does staph aureus cause disease?
Toxin, AND non-toxin mediated
Think of a gram positive bacteria that’s part of the normal human flora
staph aureus
Cytotoxins from staph aureus can break down neutrophils leading to what
tissue damage because of release of lysosomal enzymes
Staph aureus means ‘golden cluster of grapes’ in latin. What colour does it gram stain as?
purple- but GOLDEN on blood agar plates
Staph aureus can lead to what infections of the dermis and epidermis?
impetigo of the epidermis
and
cellulitis of the dermis
A dental abscess is what, in regards to staph aureus?
Infection of staph aureus where it’s become a subcutaneous abscess/ subcutaneous collection of pus.
staph aureus infection of muscle is called what?
pyomyositis
what might staph aureus do in the blood stream?
cause an infected blood clot, and be called septic thrombophlebitis
