Microbio Flashcards
Why is Vit B6 given with TB treatment?
to protect against the SE of isoniazid
(to prevent peripheral neuropathy SE, isoniazid (promotes pyridoxine excretion)
Phases of TB infeection
Primary infection - initial infection, often in childhood, often asymptomatic
latent infection - suppressed, hangs around in foci
post-primary: reactivation of latent, often immunoupresseion - can disseminate
What is a ghon focus?
a granuloma typically located in the middle/lower lung lobes.(latent TB)
What is a ghon complex?
ghon focus with lymphadenopathy (latent TB)
ranky complex
ghon complex that became calcified (latent TB)
Presentation types of TB
- constitutional sx (FLAWS)
- pulmonary TB
- TB lymphadenitis
military TB
Meningeal TB (presents as subacute meningitis)
Pott’s disease (TB of the spine)
genitourinary TB
serosa, GI, adrenal, cutaneous etc.
What is miliary TB?
pulmonary TB erodes into a blood vessle and disseminates across body
Meningeal TB
subacute presentation
add
often seen in HIV patients
Skin disease in TB
lupus vulgaris (pathognemonic)
erythema nodosum (common)
IX for TB
active
- sputum culture - gold standard (in Lowenstein Jensen media)
- sputum smear and Ziehl-Neelson stain for AFB (quicker, in reality used more often to make a dx. other stain is rhodamine auramine stain)
latent
- Mantoux test (will come back +ve if had BCG)
- IGRA ( can be used if previously vaccinated, only +ve in TB not BCG, more expensive)
Rhodamine vs rhodamine auramine stain
rhodamine - copper -> wilsons
RA - TB
Mx of TB
RIPE
R - rifampicin
I - isoniazid (+pyridoxine)
P - Pyrazinamide
E - Ethambutol
4 for 2m (RIPE) and continue 2 for 4m (RI)
Latent TB Mx
2 drugs (R+I) for 3 months
OR
1 drug (I) for 6 months
(double check)
Mx of DR TB
RIPE +
xxxx
fluoroquiolones?
name some mycobacterial diseases
Tuberculosis
Leprocy (skin changes and peripheral nerve disease)
MAC (mycobacterium avian complex, looks like pulm TB in pts with RF e.g. HIV, CF, bronchiectasis)
Swimming pool granuloma (superficial ulcers, exposed to fishtanks, aquarium)
Buruli ulcer (pt in tropics with slowly progressive, painless , ulcer)
Presentation of leprosy
hypo/hyperpigemnted nerve patches
peripheral nerve palsies
thickening of nerves
amyloidosis
median nerve palsies
150 cases annually - worldwide/USA?
Typical vs atypical pneumonia
typical presents with classic signs and symptoms of pneumonia and classic CXR changes
atypical pneumonia: no/atypical signs and symptoms, not in-keeping with CXR, don’t respond to penicillin abx because no cel wall
What abx do typical and atypical pneumonias generally respond well to?
typical - penicillins
atypical - macrolides
Strep pneumoniae pneumonia features
most common
rusty coloured sputum
gram +ve diplococcus
positive urine antigen test
H influenzae pneumonia
common in pts with COPD
gram -ve coccobacillus
Moraxella catarrhalis pneumonia
seen in smokers
gram -ve coccus
Buzzwords for Staphylococcus aureus pneumonia
post-influenza (2w bad influenza, better for 2d, then bad again)
cavitatiing lesions
gram positive cocci in grape like bunches
Klebsiella pneumonia buzzwords
alcoholics and aspiration
haemoptysis and cavitating lesion
alcoholics and post stroke (aspiration)
one more
chlamydia pneumoniae pneumonia
atypical pneumonia
3-4 w incubation
Chlamydia IgG and IgM serology
NAAT with sputum or nasopharyngeal swab.
Legionella pneumonia buzzwords
exposed to air conditioning, plumbers, travellers
vey unwell
hepatitis, hyponatraemia, lymphopaemia,
urine antigen test +ve
What pneumonia if urine antigen test is +ve
strep pneumoniae
or
legionella
Mycoplasma pneumoniae infection buzzwords
cold AIHA
erythema multiforme - can progress to SJS
young people in close proximity e.g. halls
psitacci
coxiella brunetti
gram -ve
zoonotic infection (cattle, goats, sheep)
Q-fever
add information from slides
LRTIs in HIV immunocompromised
PCP
TB
Cryptococcus neoformans
Nocardia
How does PCP present?
dry cough
desaturation on exertion
What organisms are encapsulated?
SHiNS/NHS
neisseria
haemophilus
strep
Reheated rice diarrhoea - which pathogen?
bacillus cereus
Staph aureus buzzwords (GI infection)
recent hx of bbq, short incubation because it is due to toxins, not bacteria dividing
traveller diarrhoea - organism
E coli
usually non-haemorrhagic unless EHEC
rice water stool - pathogen?
cholera
Which pathogens cause dysentery?
CHESS
campylobacter
hemorrhagic e coli
entamoeba histolytica
salmonella enterirides
shigella spp
Yersinia enterolitica (often causes terminal ileitis and adenitism can reseblne appendicitis, can be bloody or non blody
How can you classify GI infections?
secretory
inflammatory (cause dysentery)
systemic symptoms
Yersinia - what kind of pathogen is it? How and where can you get it? Sx? Dx via? Mx?
Yersinia pestis (‘‘plague’’)
gram-ve lactose fermenter
reserviour in rats, transmitted by fleas
still seen in some American national parks e.g. Yosemite
Sx
- bubonic plague: flea bites human -> swollen LN (bubo) - dry gangrene
- pneimonic plague: usually seen during epidemics, person-person spread
dx via PCR
Mx: streptomycin, doxycycline, gentamicin, chloramphenicol (in meningitis)
Entamoeba histolyitca
presents with dysebtertm chronic
t
Protozoal GI infections - examples
Entamoeba histolytica
Giardia lamblia
Cryptosporidium/
Giardia
Cryptosporidium
C diff diarrhoea buzzwords
- hx of abx
- hospital inpatient admission
Which abx are associated with c diff?
cephalosporins
clindamycin
ciprofloxacin
How do you diagnose c diff?
stool c diff toxin
visualise pseudomembrane
How do you manage c diff?
1st infection: oral vancomycin
1st recurrence (within 12 w of last episode) fidaxomicin
further recurrence - consider faecal microbiota transplant
fulminant infection - oral vancomycin + IV metronidazole
Pseudomembranous colitis
c difficile GI infection
1st line management of C diff
oral vancomycin
Pyelonephrosis
pyelonephritis with obstruction - insert nephrostomy tubes
What makes a UTI complicated?
abnormal UT
pregnancy
imunocompromised
instrumentalisation
types of UTIs
cystitis
pyelonephritis
pyelonephrosis
When are nitrites +ve on urine dip
in coliform UTIs (i.e. E coli)
they have an enzyme that reduces nitrates to nitrites
Urine MCS for UTI dx
> 10^4 colony-forming units/ml is diagnostic
10^3 colony forming units/ml E coli or staph saprophyticus
What makes a urine sample
mixed growth
squamous cells
if not UTI sx
Struvite stones - what organism?
proteus mirabilis (because it makes the urine alkaline and makes it easier for these stones to form)
klebsiella
Which organisms causing UTI indicated renal tract abnormalities?
proteus
klebsiella
Abx for UTI
lower UTI: nitrofurantoin, trimethoprim, cephalexin
uncomplicated - 3d
complicated or male - 7d
UTI in pregnancy - when not to use certain abx.
nitrofurantoin - not in 3rd TM because it causes haemolytic jaundice in the baby
trimethoprim - don’t use in 1st TM because it is a folate infection
What drug do you have to look out for when giving trimethoprim
methotrexate
Mx of pyelonephrits
IV co-amox + gent
asymptomatic UTI mx
do not treat unless they are pregnant
What is meningism?
stiff neck
photophobia
headache
+ve ??? sign
What causes meningism but is not meningitis?
subarachnoid haemorrhage
Difference between meningitis and encephalitis in presentation?
altered mental state in encephalitis
Types of CNS infection
meningitis
encephalitis
brain infection
Bacterial causes of meningitis in neontaes
GBS
listeria monocytogenes
E coli
Bacterial causes of meningitis in adults
neisseria meningitis
strep pneumoniae
Bacterial causes of meningitis in elderly
GBS
listeria monocytogenes and as adults
Bacterial causes of meningitis in immunocompromised
TB
Viral causes of CNS infections
Enteroviruses
HSV 2 - meningitis
HSV 1 - encephalisits
HIV seroconversions
Fungal CNS infections
Diagnosing meningitis
history and LP
Why do we worry about and LP in raised ICP
Coning
we worry if they have raised ICP due to a SOL, then you cone.
signs to not do LP (in rase
seizures
reduced GCS
focal neurology
papilloedema
Ix for CSF analysis in ?CNS infection
MX of meningitis in the hospital
empiric treatment (IV ceftraizone/cefotaxime (+ampicillin if baby/elderly)
steroids (dex) are controversial - yes according to guidelines (just before the 1st dose, if strep or H flu then continue for 5/7 otherwise stop)
give aciclovir if cannot rule out encephalitis
Mx of meningitis in community
IM benpen and call ambulance
Mx of TB meningitis
Commonest causes of encephalitis in the UK
HSV1
unvaccinated, measles as a child now encephalitis - diagnosis
SSPE
subacute sclerosing pan encephalitis
HIV pt or just started monoclonal treatment now has encephalitis - dx?
PML caused by JC virus (progressivve …
Management of encephalitis
empirically treat with aciclovir (MRI and CSF PCR to help identify organisms)
What organisms cause brain abscesses
mainly mixed growth -> broad spectrum and anaerobic coverage
HIV - Toxoplasmosis
Mx of brain abscess
abx (wide spectrum + anaerobe coverage)
surgical drainage
steroids to reduce swelling and Kepra to prevent seizures
What is the commonest STI?
chlamydia trachomatis
What is the commonest STI?
chlamydia trachomatis
How can chlamydia STI present?
- STI sx e.g. dysuria
- reactive arthritis
- serovars L1-3 _> lymphogranuloma venereum (proctatis followed by very swollen groin lymphobuboles)
- ophthalmia neonatorum, 1-2 w after birth
can often be asymptomatic
can you culture chalmydia?
no
What STI causes reactive arthritis?
chlamydia
How does gonorrhoea present?
typical sti sx progressing to PID
migratory arthritis
disseminated gonococcal infection
painful tendnds
ophthalmia neonatirm - first few days after birth
How can you differentiate if neonatal conjunctivitis in gonorrhoea or chlamydia?
gonorrhoea - first few days
chlamydia - 1-2 w post birth
Mx of gonorrhoea
IM cef
gold standard in dx gonorrhoea
?culture
Syphylis stages
1) painless chancre
2) unwell, condylomata lata (genitals or oral), lymphadenopathy, maculopapular rash
3) tertiary gummatous disease, aortitis, neurosyphilis, tabes dorsalis
What pathogen causes syphilis?
treponema pallidum
How do we manage syphylis?
IM benpen
How do we manage neurosyphilis?
Jarish Herxheimer reaction
when you treat syphilis they are more unwell for the first 1-2 days, can give paracetamol and maybe steroids if necessary
How do we test for primary syphlis?
darkfield microscopy of chancre sample looking for ??
or serology:
non-treponemal tests: VDRL, RPR tests (non specific)
treponema tests - TPHA, TP-EIA (stays positive in treated)
4x reduction in titre in non terponemal titre suggests resopsen to treatment
Chancroid - dx
haempphilus ducreyi
painful ulcers,
lypmhadenopathy
patients often from tropical regions
What is the commonest pathogen causing pneumonia
streptococcus pneumoniae
In someone who has had the BCG vaccine, how can you test for latent TB?
IGRA
-> only positive in infection, however, more expensive than Mantoux test.
Mantoux test is positive for both BCG and infection
Culture medium for TB and duration of culture
Lowenstein-Jensen Medium for 6 weeks -> acid fast bacilli seen
What does IGRA stand for?
interferon gamma release assay
Reservoirs for mycobacterium leprae
humans
9 banded armadillos (in the USA)
What pathogen is likely to cause pneumonia in patients with COPD?
H influenzae
What pathogen is likely to cause pneumonia in smokers?
Moraxella catarrhalis
Haemophilus influenzae
What pathogen is associated with pneumonia in alcoholics?
Klebsiella pneumoniae
What organism causes post-influenza bacterial pneumonia?
Staphylococcus aureus
Name pathogens that cause typical pneumonia
Strep pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
Staphylococcus aureus
Klebsiella pneumoniae
Name pathogens that cause atypical pneumonia
Legionella pneumophilia (zircon, travel, water, hepatitis, low Na)
Mycoplasma pneumoniae (uni student, AIHA, erythema multiforme)
Chlamydia psitacci (associated with birds)
Chlamydia pneumoniae
Name pathogens that cause atypical pneumonia
Legionella pneumophilia (zircon, travel, water, hepatitis, low Na)
Mycoplasma pneumoniae (uni student, AIHA, erythema multiforme0
Chlamydia psitacci (associated with birds)
Chlamydia pneumoniae
What pneumonia pathogen is associated with erythema multiforme?
mycoplasma pneumoniae
