micro- clin Flashcards
common clinical presentation of actinomyces infection
- what is the main differentiating factor from this infection vs the other bug that presents in the same region with a similar hx
- is an anaerobic bug that is naturally found in the gut flora
- cause disease when they get introduced into the submucosa during mechanical trauma i.e. a denal procedure
- infectious disease most commonly involves the cervicofacial region
- =chronic, nontender, indurated mass in the perimandibular area
- will grow and evolve over time –> multiple abscesses and draining sinus tracts
- HALL= sulfur granules (don’t actually contain sulfur, just look like it)
- the abscesses will drain a grainy, sand like yellow pus, it contains the Actinomyces filaments and necrotic tissue in it as well
vs Staph aureus -the leading cause of acute suppurative permandibular/parotid infection
- S. aureus will be firm, tender, and will progress rapidly
how would you classify the following sx:
- “marked wknss in the distal M and moderate wkness in the proximal M of both legs. DTRs are absent”
what is the etiology of this presentation
this is describing symmetric, ascending weakness
- Guillan Barre
- endoneurial inflammatory infiltrate, as macrophages strip away myelin sheaths and the lipid laden macrophages are hanging out
what are the 3 big oppurtunisitc infections in HIV
- when do you start prophylactic trx for each and what is the prophyaxis in each case
- P. jirovecci
- start @ CD4 < 200 OR after oral candida
- prophylaxix trx = TMP/SMX
- Toxoplasma gondii
- start @ CD4 < 100 or w (+) T. gondii IgG
- prophylaxix trx = TMP/SMX
- MAC (mycobacterium avium complex)
- start @ CD < 50
- prophylaxis trx = azithromycin/clarithromycin (macrolide) ± rifabutol
what are the big four bugs who don’t need a high concentration of organisms to causes ds (aka a small incolulum)
- Shigella (10+)
- C jejuni (~500 cells min)
- E histolytica (1-10)
- Giardia (1-10)
- what abnormality is seen on this blood smear? what is it composed of?
- what pathology is it often seen in?
reactive lymphocytes= atypical lymphocyte
- an active, cytotocix T cell/NK cell that has formed in response to a specific infection
- contains cytotoxic granzymes and perforins to kill (released in response to MHC I)
associated with infectious mono (EBV) >>>> HIV, CMV, toxo
what cells are these? name them, and use histo words to describe them
how does the influenza A virus undergo genetic shift?
what other viruses have this ability?
influenza A-
- gene segment reassortment: its genes are in segments so if two segmented viruses meet in the body, they can trade segments and create recombinant viruses very easily
- a lot easier to create new genetic changes than just point mutations in non-segmented viruses
- segment recomb can lead to change in the capsule = antigenic shift
other segmented viruses
- rotavirus = MC cause of diarrhea in kids and infants
- (a type of reovirus)
- orthomyxovirus = influenza viruses
- bunyaviridae
- arthropod viruses
- hemorrhagic fever
- hantavirus = fever, pulm edema, pulmonary fever
- arenavirus
- hemorrhagic fever, found in south america
- what pathologic mechanism enables influenza to invade human cells
- mechanism of antigenic change in influenza
- how does an influenza strain that infects other animals become capable of infecting humans
influenza
- MOI- mechanism of invasion
- flu virus is an (-)RNA virus that is enveloped within a host derived plasma membrane
- in order to interact with human cells, it needs a hemagglutinin (viral surface glycoprotein) that will allow it to attach to human epithelial cells (i.e. in the RT)
- antigenic change
- poor proofreading (by RNAdep, RNApol) –> antigenic drift
- genetic segment rearrangment –> antigenic shift
- antigenic change in the hemagglutinin that creates a tissue tropism for human epithelial cells will make the virus capable of infecting humans
which G+ species can cause impetigo?
which G+ species is PYR (+), which is PYR (-) ?
(pyrrolidonyl arylamindase)
impetigo
- Staph aureus >>> group a strep
PYR(+) = Grp A strep
PYR (-) = Grp B strep
which two organisms use a toxin against elongation factor?
corynebacterium diptheriae
pseudomonas
=exotoxin A –> ribosylation of elongation factor
ALBENDAZOLE is not an “azole” antifungal!!!
what is it??
an antihelminthic used against cutaneous larva migrans = cutaneous, red brown snake-like tracks on the skin
-often at the feet
what is the MOA of the following:
- influenza vaccine
- amantadine
- zanamavir, oseltamavir
vaccine makes Abs–>prevent entry into the cell by blocking the binding of hemagglutinin to the host cell
what organism is found on aniline dye
what process does its toxin prevent
C. diptheriae
-exotoxin A = an AB toxin that prevents protein synthesis via ribosylation of elongation factor 2
what are the organisms that are associated with infection following
- cat bite
- dog bite
- human bite
- farm animals
farm animals
- brucella, coxiella,
MOA of the following disinfectants
- alcohols
- chlorhexidine
- hydrogen peroxide
- iodine
patients who undergo organ transplant followed by immunsuppressive therapy are at risk for developing what complication?
- how can it present
- what is the GI presentation, treatment, and AE of the trx
- re-activation of latent CMV infection with end organ ds
- this can present as CMV colitis, retininits, or pneumonitis
- CMV colitis
- fever, fatigue, LQ abd pain, diarrhea
- colonic mucosal ulcers w erythema
- histo= large cells w intranuclear inclusions (eosinophilic) and intracytoplasmic basophilic inclusions –>owl eye inclusions
- trx w IV ganciclovir
- AE= neutropenia and BM suppression
what are the 4 anti-folate antimicrobials ?
-what is the difference in MOA between the 4 of them?
antifolates
- sulfanomides
- stop (PABA–> dihydrofolic acid)
- TMP
- stop (dihydrofolic acid –>THF) via inhibition of DHF-reductase
- works against bacterial cells
- MTX
- stop (dihydrofolic acid –>THF) via inhibition of DHF-reductase
- works against host cells
- pyrimethamine
- stop (dihydrofolic acid –>THF) via inhibition of DHF-reductase
- works against protozoa = malaria and toxoplasma
describe what you are seeing
-most likely cause of fungal infection in an immunocompromised patient??
candida
= yeast and pseudohyphae on light microscopy
how is EBV transmitted
through saliva
aka kissing
treatment for gonorrhea vs chlamydia infection
gonorrhea = ceftriaxone
- GONE SWIFT(ceft)er than an AXE
chlamydia = doxycycline or azyithromycin
- lAZY day @ the CHLAM DOX (docks)
corkscrew shaped spirochete = ?
- mechanism of transmission
- important diagnostic sx
leptospirae
- host in wild animals’ PCT and excreted in their urine –> transmitted to humans via contact w fresh water outdoors that has infected animal urine
- mostly a flu-like illness with conjunctival suffusion = looks like conjunctivitis but without inflammation
discuss the specific pathology and etiology of cardiac complications of teritiary syphillis
tertiary syphillis (treponema infection)
- associated w aortic regurge (decscrescendo murmur heard on the right sternal border during diastole)
- start with vasa vasorum endarteritis –> aortic aneurysm –> aortic regurge + mediastinum widening
- what is the mainstay trx of malaria
- what is the trx for strains that are resistant to the mainstay- associated with what subtypes of malaria
- mainstay = chloroquine
- chloroquine + primaquine = P falciparum + P ovale
- resistant to chloroquine = atovaquone + proguanil
common sx/PE findings in hand-foot-and-mouth ds
what is the causative organism? what other pathologies can it cause?
HFaM Ds= rash on “extremities” with buccal mucosa and soft palate ulcers
what is procalcitonin and how is it useful
an acute phase reactant
inc in response to bacterial toxin : dec in response to viral toxin
can be used to differentiate causes of CAP
what NTs are inhibited by tetanis and botulinism
tetanus = inhibit GABA and glycine = rigid
botulinism = inhibit Ach = floppy baby
what organism is this
(arrow is a huge hint)
how will it present and what are the other three version
schistosoma mansoni = LATERAL spine
what pathologic finding is seen here? dx?
plasmodium falciparum = malaria
what is the bull’s eye lesion associated with? what is the etiology?
what is the official PE finding?
lyme disease
spirochetes spreading through the dermis =
“annular erythematous lesion with central clearing” = erythema migricans
child with lacy, reticular rash on the trunk and extremities, develops red, flushed cheeks
red, flushed cheeks = slapped cheek rash
- lacy, reticular rash
parvovirus B19 infection = erythema infectiosum
- 5th disease= benign childhood ds
- parvovirus B19 replicates in erythrocyte precursors in the BM
who are the double stranded DNA viruses
- enveloped
- non-enveloped
- neonate born with hydrocephalus, jaundice, hepatosplenomegaly, retinal exudates
- histo= numerous intracellular crescent shaped organisms
dx? why did this happen ?
toxoplasma gondii
- pregnany women eat raw or undercooked meat –> intracellular toxo infection can be spread cross the placenta
what are the two types of disease that can be seen with salmonella
- dif pathophysiologies that lead to the diff disease
- clinical manifestations
vibrio vulnificus
- transmission
- clin picture
- transmission= from consumption of raw oysters or wound contamination during water sports
- clin picture= asx in healthy patients : in those w liver ds or iron overload, can cause rapid necrotizing fasciitis, septic shock, and death
asplenia is associated with increased risk of infection by what organisms
those with a polysaccharide capsule
- Strep pneumoniae
- H. influenzae
- N. meningitidis
**the three bacteria who tell you exactly what they are going to do**
psuedomonas
- found where
- causes what clinical presentations
found in water sources like waterslides, hot tubs, etc.
- folliculitis= red papules all over the body with central pustules
- wound and burn infection
- pneumonia (especialy in CF pts)
- external otitis = swimmers ear
- osteomyelitis (esp in diabetic pts and IVdrug users)
- endotoxin–> fever and shock
what organism is seen here
what skin findings can it cause
staph aureus= grape like clusters
=skin and ST abscesses- colonize the anterior nares –> spread to the skin
- =localized pustule that evolves into a painful nodule with a necrotic, purulent center with surrounding indurated erythema
patients receiveing parenteral nutrition from an parenteral cathether are at increased risk of what infection
candida (show up as yeast)
parvovirus is common in what population and presents how in
- aduts
- children
- fetuses
- sickle cell
parvovirus B19 is most common in children and school teachers (School outbreaks)
- aduts
- arthralgias, arthritis
- with or without rash
- children
- slapped cheek rash that appears AFTER the break of fever
- aka “erythema infectiousum” or ‘fifith ds”
- fetuses
- =TORCH
- hydrops fetalis
- x erythropoeisis –> profound anemia + ascites
- sickle cell