Rx_01.20 (Microbio) Flashcards Preview

USMLE Step 1 > Rx_01.20 (Microbio) > Flashcards

Flashcards in Rx_01.20 (Microbio) Deck (19)
1

Enfurtivide: MOA & use

  • antiretroviral therapy
  • MOA = entry inhibitor
    • blocking interaction between gp120 & host CD4 or by interfering w/viral gp41-mediated fusion

2

Rocky mountain spotted fever presentation

  • vacation/travel to South Atlantic states (NC, TN, etc)
  • classic triad = H/A, fever, rash
    • rash = palms/soles/wrists ==> trunk

3

Rocky Mountain spotted fever cause/spread/tx

  • cause = Rickettsia rickettsii
  • spread via ticks = 
    • Dermacentor andersoni
    • D. variabilis
  • tx = immediate antibiotic therapy
    • tetracycline (e.g. doxycycline)
    • chloramphenicol

4

Causes of osteomyelitis in sickle cell patient

  • S. aureus
  • Salmonella

5

Cholera toxin: MOA

  • A1 subunit ==> active adenylate cyclase ==> increased cAMP ==> increased chloride ion secretion ==> secretory diarrhea

6

Hepatitis E presentation + pathology

  • Hepatitis E 
    • fecal-oral
    • high infection rates @ sub-saharan Africa
    • high mortality in pregnant women
  • Path ==> focal hepatocyte damage ==> patchy necrosis on biopsy

7

Characteristics of C. albicans

  • germ tube-positive fungus
  • ==> white plaques (thrush) @ immunocompromised individuals (common in HIV)

8

branching rods on culture from pt w/oral infection ==> ? + tx

  • Actinomyces israelii
    • gram-positive 
    • branching rods
    • anaerobic
    • part of normal oral flora
  • Tx =
    • IV penicillin for 2-6 wks
    • oral penicillin or amoxicillin 6-12 months

9

Bartonella henseleae causes....?

  • cat-scratch fever
    • local, chronic lymphadenitis 
    • commonly @ children
  • bacillary angiomatosis 
    • usually @ AIDS patients
    • ==> proliferation of blood and lymphatic vessels ==> "mulberry" lesion in skin

10

Characteristics of Bartonella henselae

  • small gram-negative
    • "proteobacterium"
  • visualized w/Warthrin-Starry stain

11

Rotavirus mechanism of infection

  • enters host cell by endocytosis
  • transcribes viral mRNA w/ a viral RNA polymerase present in virion

12

Presentation of reactive arthritis/"Reiter's syndrome" + cause

  • urethritis, conjuctivitis, arthritis
    • "can't pee, can't see, can't climb a tree"
  • derm sx
    • most plaques on glans penis
    • crusting papules
  • usually male, w/HLA-B27
  • autoimmune rxn post-infection:
    • Chlamydia trachomatis, N. gonorrhoeae
    • Salmonella, Shigella, Yersinia, Campylobacter

13

Characteristics of Legionella pneumophila pneumonia

  • occurs @ older pts w/hx of alcoholism, smoking, DM, chronic illness, immunosuppression
  • legionella =
    • gram-negative rod (coccobaciliary)
    • stains w/silver stain
    • cultures on charcoal yeast extract

14

Protective factor for HIV infection

  • homozygous for CCR5 mutation
    • CCR5 = chemokine receptor on macrophages that facilitates viral entry
  • CCR5 mutation ==> immunity to certain strains of HIV
  • present in primarily caucasian individuals

15

Common cause of croup + virus type

  • cause = paramyxoviridae family (parainfluenza virus)
  • viral characteristics
    • envelope + helical capsid
    • RNA virus
      • single-stranded
      • negative-sense
      • linear, nonsegment

16

filamentous, gram-positive organism that is weakly acid-fast = 

Nocardia asteroides

17

Characteristics/tx of Nocardia asteroides

  • filamentous, gram-positive
  • weakly acid-fast
  • ==> lung abscesses @ immunocompromised patients
  • Tx = 
    • sulfonamides (MOA: inhibition of dihyropteroate synthetase)

18

Yellow fever characteristics

  • flavivurs
    • SS, RNA virus
    • mosquito vector
  • sx = H/A, photophobia, MSK pain, jaundice
  • labs/biopsy
    • AST > ALT
    • councilman bodies = eosinophilic degeneration + condensed nuclear chromatin

19

Mechanism of staph scalded skin syndrome

  • staph releases (epidermolytic) exotoxins A and B
  • exotoxins bind desmoglein 1 @ desmosome ==> epidermal separation @ stratum granulosum
  •  ==> blistering

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