MedEd Micro 2 Flashcards
causes of immunocompromise
immunodeficiency syndromes
acquired - HIV, iatrogenic, lymphopaenia, malnutrition, DM
organ specific - structural lung disease (COPD, CF), splenectomy
what organisms are people with no spleen at risk of
encapsulated bacteria
ie NHS
neisseria
hamophilus
strep
consequences of immunocompromise
unusual organism infections
unusual site infections
HIV specific infections
PCP
JC virus
toxoplasmosis
microsporidium
MAC
(TB & CMV more severe)
CF specific infections
burkolderia cepacia
anti TNFa specific infections
JC virus
HIV pts can get common infections in weird places - 2 examples of the bug with location
CMV colitis
oesophageal candidiasis
what weird site infection do sickle cell pts get and from what bug
salmonella septic arthritis
prophylaxis for HIV / splenectomy pts
vaccination (splenectomy)
ABx - co-trimoxazole (HIV)
what feature of influenza allows antigenic shift
multi segmented genome
types of influenza
A and B
technically 4 types but C and D aren’t that clinically relevant
which type of influenza is worse
A
(its the pandemic one)
what 3 features of influenza allow it to have pandemic risk
novel antigenicity
efficient replication in airways
efficient transmission between people
2 processes that allow novel antigenicity
antigenic shift
antigenic drift
what is antigenic drift
accumulation of errors over time
what is antigenic shift
organism infected with 2 strains of influenza at the same time –> RNA from both strains mix in the same cell –> genome of virus changes
problem with antigenic drift
pre formed ABs from previous infection are no longer effective against current strain
how many chunks of RNA does influenza have
8
how common is antigenic shift vs drift
drift is common, shift is very rare - esp to cause a functional virus as often the mix produces nonsense virus
2 most important genes in influenza
neuraminidase
haemagglutinin
what does neuraminidase do
cleaves sialic acid, facilitating viral release from cells
what does haemagglutinin do
binds to sialic acid, facilitating viral entry
key pandemic feature of haemagglutinin
prone to antigenic drift
key pandemic feature of neuraminidase
prone to antigenic shift
how do you determine strain of influenza
RT - PCR
where are haemagglutinin and neuraminidase found
cell SURFACE
influenza antivirals
PO oseltamivir (tamiflu) ** key one
inhaled zanamivir
IV peramivir
oral baloxavir
oral amantadine
how does oseltamivir work
neuraminidase inhibitor
how does baloxavir work & when is it used
endonuclease inhibitor
only in first 2 days of infection
how does amantadine work
m2 antagonist
problem with amantadine
easy to become resistant to it - most influenza strains are resistant to it, so not used anymore
what herpes presentation indicates uncontrolled HIV infection
herpes oesophagitis
JC virus causes what presentation
progressive multifocal leucoencephalopathy (PMLE)
what is this persons Hep B status
HBsAg +
HBsAB -
HBcAB IgM +
HBeAg +
HBeAB -
acute hep B infection
what does val infront of an antiviral indicate & clinical indication
increases bioavailability + less effected by first pass metabolism
easier to take orally
tx ladder of human herpes viruses
aciclovir or ganciclovir
foscarnet
cidofovir
usual first line Tx for non herpes viruses
cidofovir 1st line
why do we not just treat everyone with cidofovir if its 3rd line HHV and 1st line non HHV
dirty drug - nephrotoxic, ocular toxicity, BM suppression
what are herpes simplex in terms of HHV
HHV 1 & 2
brain manifestations of HSV1 vs HSV2
1 = HSV encephalitis
2 = HSV meningitis
PCs of HSV1
herpes labialis (oral ulcers)
HSV encephalitis
PCs of HSV2
genital herpes ulcers
HSV meningitis
rarer presentations of HSV
HSV oesophagitis / colitis - HIV!!!!
eczema herpeticum
herpetic whitlow
disseminated cutaneous herpes - imm comp
what is herpetic whitlow
herpes on the finger
who gets herpetic whitlow
healthcare workers !!
1st line tx of HSV
aciclovir
what can initial enoculation with HSV look like (more commonly than in reactivation)
herpes gingivostomatitis - ulcers around mouth
what HHV is VZV
HHV3
PC of VZV
chicken pox and shingles
who gets more serious chickenpox infections
adults - esp imm supp / foetus
aka shingles
herpes zoster
2 key risks of shingles
opthalmic herpes zoster
ramsay hunt syndrome
what is ophthalmic herpes zoster
shingles of v1 –> damage of retina
sign of opthalmic herpes zoster and what this actually is
hutchinson sign
vesicles on the nose tip
what is ramsay hunt syndrome
facial nerve shingles
can get bells palsy, ear pain + vesicles in ear
what is not part of the VZV tx esp in children & why
ibuprofen
- increases secondary skin infections esp nec fasc
complication post shingles
post herpeticum neuralgia
- pain in distribution of dermatome
what is HHV4
EBV
PC of EBV
infectious mononucleosis
- fever, pharyngitis, lymphadenopathy
- hepatosplenomegaly
how can the lymphadenopathy picture differentiate EBV from tonsilitis
EBV affects posterior cervical chain
tonsilitis affects anterior cervical chain
what else can cause infectious mononucelosis
CMV
toxoplasmosis
what else can cause a similar picture to infectious mononucleosis
HIV seroconversion !
what lab findings strengthen a Dx of EBV
monospot test
atypical lymphocytes on smear
how is EBV usually diagnosed now
EBV serology
tx of EBV
usually supportive
gancyclovir if really bad
2 pieces of advice for patient with mono
avoid contact sports - splenic rupture risk
avoid alcohol - can give hepatitis
3 associated diseases after EBV
burkitts lymphoma
post transplant lymphoproliferative disorder
nasopharyngeal carcinoma
what is HHV5
CMV
2 potential PCs of CMV
asymptomatic or mononucelosis picture
buzzword of CMV
owl’s eye inclusion bodies
4 PCs reactivation of CMV in imm supp
pneumonitis
retinitis
colitis
encephalitis
tx of CMV
gancyclovir / valgancyclovir
CT of CMV pneumonitis
ground glass widespread appearance
what does CMV retinitis look like
widespread cotton wool spots
what does CMV colitis look like
like HSV oesophagitis - hard to differentiate
owls eye inclusion body !
name 3 other HHV and what they cause
HHV6 & 7 - roseola
HHV8 - karposi’s sarcoma
complication of roseola
encephalitis (rare) –> causes lots of febrile seizures
association of HHV8
castleman disease
primary effusion lymphoma
what is primary effusion lymphoma
very poor prognosis diffuse large B cell lymphoma
what is castlemann’s lymphoma
lymphoproliferative disorder
what is karposi’s sarcoma
lymphatic endothelium proliferation
what is the problem with karposi’s sarcoma
lesions on the skin are fine ish
but often associated with lesions internally which can haemorrhage massively
what do adenoviruses cause in imm comp
pneumonitis
haemorrhagic cystitis
meningioencephalitis
colitis
what does JC virus cause in helathy vs imm comp ppl
healthy = nothing
imm comp = PML
who is most susceptible to JC virus
monoclonal ABs pts
HIV
Tx of JC virus
no antivirals really
treat imm supp
what does BK virus cause & who do we worry about it in
transplant pts !!
nephropathy - kidney transplant pts
haemorrhagic cystitis - BM transplant pts
which hepatitis viruses cause acute infection
A and E
common things between hep A and E
both cause acute infection
both faecal-oral
both seen in travellers
similar clinical presentations
can be STIs esp in MSM !!
rarely cause chronic infection, just acute
progression of PC of hep A/E
- inc incubation period and resolution period
incubation period 2-6 weeks
prodromal malaise
jaundice, hepatitis, cholestasis
resolution ~ 2 months
what complication is rare in hep A and E
fulminant hepatitis (can happen but v v v rare)
who would get fulminant hepatitis in hep A / E
A = elderly
E = pregnant women *** buzzword
tx of hep A / E
none - symptomatic
which hep has a vaccine
hep A and B
how is hep B transmitted
contaminated blood / fluids
vertically
how does hep B present & for how long
acutely with hepatitis
can last up to 6 months
is hep B fulminant
rarely
what % of people fail to clear hep B and what happens then
5-10%
- become chronically infected
what can uncontrolled hep b cause
cirrhosis
HCC
what is the RF of hep B becoming chronic
younger age !!
what does hep B sAg + indicate
have the virus present
what does hep B sAB + indicate
you are immune (have neutralising ABs)
what does hep B cAB + indicate
you have / had hep B
which hep B cAB is present in acute vs chronic response
IgM = acute
IgG = chronic
do hep B cAB confer immunity
NO - just shows you have seen the virus. its HBsAB that shows immunity
what is the hep B eAg a marker of
infectivity (present = highly infectious)
what does hep B eAB indicate
not very infectious
pt with only hep B cAB + only
either JUST cleared the infection
infected AGES ago
hep b tx
tenofovir 1st line
entecavir can be used
looooads of others that aren’t as relevant for path
follow up of hep b
6 monthly screening for HCC - USS / AFP
how can hep B be prevented
vaccination !!
when do you get hep D
only if you have hep B too
3 manifestations of hep D with PC
coinfection at the same time with hep B –> ++++ severe acute hep B
superinfection (flare of hep B then get hep D) –> exacerbation of chronic hep B
aggressive, difficult to treat chronic hep B
Ix for hep D
anti HDV ABs
prognosis and tx of hep D
very very bad - get cirrhosis quickly
IFNa but not that good
how is hep C transmitted
bodily fluids
vertically
what is hep C the opposite of and why
hep B
- rarely get acute hepatitis, sometimes coryza
- very common to get chronic 60-80%
how does chronic hep C present
cirrhosis (dont get initial hepatitis so dont know you have it)
unusual presentations of hep c
glomerulonephritis
cryoglobulinaemia
vasculitis
Ix of HCV
viral load
serology less useful
hep c tx
direct acting antivirals (target parts of hep c genome)
how is tx for hep c judged and what is this
sustained virologic response (SVR)
- at 12 weeks, do you have a detectable viral load
is there a vaccine for hep c
no
define pyrexia of unknown origin
> 38.3 degrees
+
3 weeks
+
no known cause
+
one week of Ix
3 specific situations of PUO
nosocomial
neutropaenic
HIV assoicated
3 specific situations of PUO
nosocomial
neutropaenic
HIV associated
what can cause a fever
infection - classical or weird ones / weird foci
cancer - haem ones esp
AID
rare familial diseases - eg FMF, immunodefs
weird foci infections
IE
psoas abscess
epidural abscess
which AIDs can cause fever
rheumatology ones
vasculitis
still’s disease **buzzword
buzzwords of typhoid fever PC
rose spots
nosebleeds
constipation
fagets sign
what ABx is usually used to treat weird infections
doxycycline
cause of typhoid
salmonella typhi or paratyphi
NOT the other salmonella
who gets typhoid and how
travellers from India
foecal - oral
what is fagets sign
relative bradycardia (usually HR increases if fever)
incubation of typhoid
1-2 weeks
gold standard Ix for typhoid
BM culture
actual tests for typhoid
cultures
serology (widal test)
tx of typhoid
ceftriaxone
where does typhoid live
peyers patch
complication of typhoid
haemorrhage from ruptured peyers patch
where is the dengue traveller coming back from
SE asia - thailand / cambodia
transmission of dengue
mosquitoes
how many serovars are there of dengue
4
2 buzzwords of dengue
retro-orbital headache
suburn rash
incubation of dengue
2 weeks
tx of dengue
supportive tx as they will get better on their own usually
2 serious ways dengue can present
dengue shock syndrome
dengue haemorrhagic fever
why do people get the more serious dengue presentations
previously infected with dengue (more common in people who live in these countries)
cause of malaria
plasmodium spp
where do you travel to to get malaria
africa / south asia / se asia / central or south america
how does malaria present
paroxysms (episodes) of fever and rigors
anaemia, jaundice, hepatosplenomegaly, haemaglobinuria
incubation of malaria
depends on species infected with
fatal complications of malaria
shock
ARDS
cerebral malaria
blackwater fever
DIC
what is blackwater fever & classical sign of it
pronounced haemolysis –> kidney damage
get BLACK urine
how is malaria Dx
thick and thin blood film
name the species of malaria
plasmodium:
falciparum
vivax
ovale
knowlesi
malariae
which species of malaria causes the fatal disease
fallciparum
which species of malaria requires treatment of hypnozoites (bcos they are the only ones to produce hypnozoites)
vivax and ovale
which species of malaria have tertian pattern with 48hr paroxysms
falciparum, ovale, vivax
which species of malaria have quotidian patterns and how long are the paroxysms
knowlesi - 24hrs
malariae - 72hrs
what is schizont and where do they form
big ball of developing malaria
- in liver / RBC
describe malaria lifecycle
mosquito bites you
releases sporozoites
travels to liver and forms schizont
schizont ruptures - releasing immature parasites to blood stream
each invades a RBC
forms schizont in RBC which ruptures and releases again
continues cycle
which bit of the cycle is responsible for periods of fever
schizont in RBC rupturing
which malarias can present 6-7 years after exposure in acute phase and why
ovale and vivax
- make hypnozoites which can lay dormant in liver then randomly make schizont later
tx of severe malaria
IV artesunate
indications for IV artesunate in malaria
severe
parasitaemia >2%
hypoglycaemia
metabolic / lactic acidosis
severe anaemia (70/80ish)
tx of less severe malaria
artemesin combo tx or chloroquine
what other tx does vivax / ovale need
primaquine
buzzwords of brucellosis RFs
raw dairy / unpasteurised milk
cattle / farms
buzzwords of brucellosis PC
lower back pain (epidural abscess)
epididymo-orchitis
dx of brucellosis
cultures
tx of brucellosis
doxycycline
buzzwords of rabies RFs
dogs / bats bites
what causes rabies
lyssavirus
buzzwords of rabies PC
hydrophobia
excessive salivation
furious / dumb encephalitis (angry or sedated)
incubation of rabies
1-3 months
tx of rabies & time frame
rabies Ig / vaccine
only BEFORE they are sx - otherwise dead
what CSF PCR result is pathognomonic for rabies
negri bodies
** buzzword
potential dx of rabies
biopsy from nape of neck
usually just clinically tho as its so rapidly progressing
buzzwords for RFs for plague
rats esp fleas on rats
buzzwords for PC of bubonic plague
buboes - massive lymph nodes which when aspirated show a dense BLACK fluid
cause of plague
yersinia pestis
tx of plague
doxycycline
how can bubonic / septicaemic plague also present
peripheral gangrene
buzzwords for RFs for leptospirosis
rat urine - outdoor water activities
buzzwords for PC of leptospirosis
jaundice
conjunctival suffusion (dry, no exudate)
incubation of leptospirosis
1 week
tx of leptospirosis
doxycycline
ceftriaxone if severe
buzzwords for bartonellosis RFs
kittens
“cat scratch fever”
buzzwords for bartonellosis PC
lymphadenopathy proximal to scratch
papule where scratch
parinaud oculoglandular syndrome
what is parinaud oculoglandular syndrome
conjunctivitis
big lymph nodes infront of ear
tx of bartonellosis
doxycycline
buzzwords of lyme disease RFs
ticks (ixodes tick) - usually been outdoors in woods etc
buzzwords of lyme disease PC
bullseye rash (erythma migrans)
–> Dx of lyme if present
complications of lyme disease
arthralgia
heart blocks
tx of lyme disease
doxycycline
buzzwords of leishmaniasis RFs
sandflies
buzzwords of leishmaniasis PCs
visceral - hepatosplenomegaly, pancytopaenia
cutaneous - well demarcated lesion at site of bite. can be very destructive ulcers
mucocutaenous - VERY destructive of mouth / nose
dx of leishmaniasis
microscopy
tx of visceral leishamniasis
liposomal amphoterocin B
buzzwords of anthrax RFs
wild animals - spores in hairs
buzzwords of anthrax PC
eschars (boil on skin –> painless necrotic skin lesion)
widened mediastinum (pulmonary anthrax)
dx of anthrax
microscopy or culture
tx of anthrax
doxycycline
classical superficial fungal infections
dermatophytoses (tinea / ringworm)
pityriasis versicolor
cause of tinea
trycophytum rubera
which tinea can be treated with topical antifungals
tinea pedis (athletes foot)
tinea cruris (groin)
tinea corporis (body)
tinea manuum (hands / palms)
which tinea can’t be cleared with topical antifungals, and require systemic antifungals
tinea capitis (scalp / hair)
tinea unguium (nails)
PC of pityriasis versicolor
multiple tan/brown lesions across trunk (hypopigmented in darker skin), abdo, face
tx of pityriasis versicolor
antifungal shampoos / topical azoles
PC of candida
oral thrush
vaginal thrush
disseminated
oesophageal
who gets the following candida:
oral
oesophageal
dissemninated
asthmatics bcos of steroid inhaler
severe imm supp
central access lines
2 specifc blood tests for candida & results
beta D glucan +
galactomannan -
tx of severe candida
amphoterocin B
echinocandins
3 PC of aspergillus
aspergilloma
invasive aspergillosis
ABPA
blood test result for aspergillus
beta D glucan +
galactomanna + (candida in comparison in negative)
who gets aspergilloma
pre existing cavity in lung eg abscess
who gets invasive aspergillosis
imm supp
what is ABPA
hypersensitivity reaction to colonisation
- NOT an infection
tx of aspergillus
amphoterocin B
(NOT ABPA - not an infection - give steroid)
if aspergilloma - surgical removal of the fungi
buzzword of sporotrichosis (RFs and Sx)
contracted from rose thorns - gardeners / farmers
necrotic patchy rash spreading proximally
buzzword for mucormycosis
DM pts following COVID
gets rhinocerebral infection (big necrosis on face)
what is a prion
misfolded PrPc protein (should be alpha helix –> now beta pleated sheet which can’t be broken down)
what do prions do to the normal PrPc proteins
make the normal ones misfold to form prions
PC of prion disease
rapid neurodegeneration
most common prion diseases
creutzfeldt jakob disease
3 forms of CJD and prevelance
sporadic 85%
familial 5-15%
acquired <1% eg iatrogenic. inc variant !!
what causes variant CJD
eaten beef with mad cow disease
dx of CJD
clinically
biopsy PM
in variant –> can do tonsillar biopsy
buzzwords of kuru
papau new guinea
ritual cannibalism
2 familial prions
fatal familial insomnia
gerstmann-straussler-scheinker (better prog)
