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
why does bacterieamia cause blood pressure to fall
due to the immune reaction causing blood vessels to dilate.
can therefore cause sepsis.
What might staph aureus do in the central nervous system?
get into the spine and cause an epidural abscess
or cause bacterial meningitis
what’s happening in staph aureus infective endocarditis?
grow on heart valves in clumps called vegetations
staph aureus can cause biofilm t or f
t, Iv catheters for example
what is toxic shock syndrome, really?
a cytokine storm that results in physiological changes, such as fever, low blood pressure and poor end organ perfusion that can result in death.
hemolysin toxin from staph aureus does what?
It destroys erythrocytes, releasing their hemoglobin which contains iron. Which it uses for it’s own metabolism.
Other than the TSS1 toxin caused by staph aureus, what toxin causes toxic shock syndrome if it enters the bloodstream?
enterotoxin
Methicillin sometimes kills staph aureus, but cant kill MRSA. What type of antibiotic is it?
beta lactam
what are the two categories of MRSA
what antibiotics (and examples please) treat MRSA commonly?
glycopeptide antibiotics, such as vancomycin or clindomycin
whats VRSA staph aureus
vancomycin resistant staph aureus
diagnosis for septic shock
Serum lactate levels @ 2mmol/l
Low mean arterial pressure @ 65mmHg or below. (requiring vasopressors)
how to treat septic shock
Obvs sepsis 6
then vasopressors
what are the 3 essential phases of sepsis
1) release of bacterial toxins
2) release of mediators
3) effects of these excessive mediators
common bacterial causes of sepsis, is: s. aureus, e. coli, some strep
In sepsis, what do i mean by immunoparalysis?
There is an increases in inflammatory response, but then there is an ‘immunoparalysis’, failure of the body to mount an immune response.
Does coagulation increase or decrease in sepsis inflammatory response?
increase
With sepsis, what are the common infections that cause septicaemia?
Pneumonia
UTI
abdominal infections
What is the sepsis 6?
Take 3 give 3
take blood culture
take blood lactate
measure urine output (marker of renal dysfunction)
give oxygen
give IV fluid
give antibiotics
Influenza A, B, C = which to worry about/more severe, and is also the only one to be present in animals as well?
a
Incubation period of influenza?
2-4 days
In severe cases of influenza, what antiviral medication should you give? (for only A and B)
(For someone at risk, really)
oseltamivir
or inhaled zanamivir
How quickly should you give oseltamivir?
NB can also give this as post exposure prophylaxis.
Within 48 hours of infection
Because of the risk of secondary bacterial pneumonia, patients with ‘flu symptoms and a fever for greater than 4 days, should have an
malaria is disease of
red blood cells
After being in the bloodstream initially, where does malaria parasites go?
liver (can sleep there, hence recurrent malaria) then leaves again and invades red blood cells. They produce female and male gametocytes. Then taken up by new mosquito, and becomes a zygote
Clinical features of malaria?
Non specific
Kinda like the flu
abdo pain, fever, headache, sore throat, cough, frequency, aching bones etc
Often just fever
Why jaundice in malaria?
increase in red cell break down = increase in bilirubin
Arch back in a case of malaria, is suggestive of what
specifically cerebral malaria
parasites disrupt and compromise circulation in the brain
Diagnose malaria how?
1) thick and thin blood film to check for parasites (look at overnight)
2) rapid malaria antigen test kit (can be used by patient themselves as well as in hospital)
Severe malaria is when the parasite count is more than what?
2%
Treat malaria how?
riamet (nb from that chinese plant)
quinine (has some side effects)
Treat severe malaria how?
IV artesunate
IV quinine
often taken with clindamycin
turns oral with improvement of a few days
Three negative samples taken over how many consecutive days, to exclude malaria?
Due to the parasites being released from red blood cells into the blood every 48-72 hours
Three negative samples taken over three consecutive days are required to exclude malaria due to the parasites being released from red blood cells into the blood every 48-72 hours
What is a common side effect of artesunate?
haemolysis
Clinical presentation of typhoid fever, how long is usual duration?
4 weeks
2nd week, fever peaks
3rd is when complications occur
Treatment of typhoid?
Drug of choice =
Classic presentation of dengue fever?
sudden fever
severe headache and pain behind the eyes
pain in the bones
rash
nausea or vomiting
Diagnosis of dengue
PCR in the blood
Dengue management?
fluids, fresh frozen plasma, platelets
When does dengue shock syndrome occur?
Or dengue haemorrhagic fever?
When you’ve had it before, so low platelets already
When does the critical phase of dengue fever occur?
3rd day of fever, lasts for 24 or 48 hours
Schistosomiasis> what symptoms in the first few hours, then after 8 weeks?
swimmers itch
blood in urine or semen
Ebola is what type of fever
viral haemorrhagic fever
Lyme disease incubation period
7-14 days
B. burgdorferi bacteria from a tick bite multiplies in what layer of the skin?
dermis
Treatment for lymes disease
2-4 weeks amoxicillin or doxycycline
What neurological manifestations of lyme disease may occur?
lower motor neurone facial nerve palsy
What is the most common cause of facial nerve palsy in children?
lyme’s diease
How to diagnose Lyme disease in particular?
Routine Lyme disease serological testing to check for antibodies. But also send CSF and serum samples (taken on the same day) for neurological Lyme disease.
What is brucellosis?
An infection you can catch from unpasteurised milk or cheese, or from contact with infected animals.
Leptospirosis caught how?
Carried by rats initially, spread through urine, caught from water sources. Maybe water sports. Penetrate through skin.
Leptospirosis can lead to Weil’s disease, which is characterised by what triad
jaundice
AKI
bleeding
Investigations for leptospirosis?
when clinically high suspicion,
Serology for IgM and IgG
Treat leptospirosis how?
Amoxicillin or doxycycline
IV ceftriaxone if severe, just like Lyme
Incubation of rabies?
1-3 months, can take years.
Pathogenesis of rabies
Bitten
Travels from muscle to peripheral nervous system, to central nervous system, to the brain to cause encephalitis = confusion, seizures, difficulty speaking, feeling weak
Most common symptoms of rabies
hydrophobia
insomnia
confusion
agitation
coma
occasionally ascending paralysis
why hydrophobia in rabies
virus is in salivary glands and doesn’t want to be diluted by taking water
almost always fatal once symptoms appear
Investigations for Ebola?
PCR
Serology for IgM and IgG
Why do we use oral vancomycin in c difficile, vs IV?
Because it’s such a large molecule, it won’t really be absorbed, so it stays in the gut where the infection is rather than going into the system.
Symptoms of red man syndrome for use of vancomycin?
flushing
erythema
pruritis
affecting upper body more than lower
How to manage red man syndrome for vancomycin
stop infusion
administer antihistamine
can restart slowly once symptoms resolve
Why do you have to monitor vancomycin so much?
It’s nephrotoxic.
What type of drug is gentamicin?
Aminoglycosides. which is bacteriostatic.
what drug to give in breast feeding and pregnancy?
erythromycin
Give 3 examples of broad spectrum antibiotics
azithromycin
amoxicillin
ciprofloxacin
doxycycline
gentamicin
would an intra-abdominal infection require broad or narrow antibiotics
broad
would gastro-enteritis require broad or narrow spectrum antibiotics
broad
does otitis media require broad or narrow spectrum antibiotics
broad
How would you treat tonsilitis infection?
penicillin or broad
How to treat flu
oseltamivir oral
or
inhaled zanamivir
How to treat a UTI
nitrofurantoin!
(maybe amoxicillin if that doesn’t work)
How to treat cellulitis?
flucloxacillin
How to treat clostridium difficile
oral vancomycin
How to treat meningitis?
aciclovir because viral or also IV vancomycin for bacteria if indicated like recent travel, or recently lots of antibiotics
How to treat malaria
riavet or quinine plus broad
treat vaginal thrush how? And what is it?
Candida
treat it with clotrimazole cream
Genital candidiasis has similar symptoms to a UTI. What symptoms might distinguish it?
cottage cheese discharge
itch, rash
UTI has similarly, dysuria
3 most common fungal things
aspergillus
tinea
candida
Clinical diagnosis of tinea is usually based on clinical presentation. What is this clinical presentation?
scaly itchy skin
raised anular patches with typical central clearing, of asymmetrical distribution
Jock’s itch = what
tinea
Ringworm is what fungal infection? and therefore treat with what
tinea, treat with terbinafine cream probably
where is aspergillus found?
soil compost organic matter, air conditioning systems, uncovered attic water tanks, damp buildings.
Symptoms of aspergillosis mimic respiratory disease, and as it often occurs in patients with already compromised lungs, it kinda just looks like exasperation. Just like, ‘hey my symptoms are getting worse’
What symptoms might clue you into thinking there is a fungal cause?
maybe the fact there is a fever?
NB you do of course have weight loss, cough, haemoptysis
BUT aspergillosis has fever as well!
How to treat invasive pulmonary aspergillosis?
IV anti-fungal meds as an in-patient
Symptoms of invasive pulmonary aspergillosis?
pleuritic chest pain
sob
sinusitis
haemoptysis
but crucially, other organs are involved because it spreads haematogenously > kidney, brain, thyroid, GI tract, eyes, skin.
Herpes zoster virus i.e. shingles vaccine is given to what age group?
70 plus
Herpes zoster virus i.e. shingles is what
It’s the chicken pox infection travelling along the nerve and causing a crusty rash on the skin along it
Normal levels of PaO2
10.7-13.3
Normal levels of CO2
4.7-6
Normal HCO3 levels
22-28mmol/l
Normal pH
7.35-7.45
Normal lactate levels =
0.5-1mmol/l
