Microbiology Flashcards

1
Q

Genital ulcer disease causes

A
  • syphilis
  • genital herpes
  • chancroid
  • granuloma inguinale (donovanosis)
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2
Q

Syphillis

A

treponema pallidum

single, painless ulcer at inoculation site with heaped up border and clean base

dx with VDRL/RPR and darkfield microscopy

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3
Q

genital herpes

A

HSV

multiple painful superficial vesicles or ulcerations with erythematous base

dx with PCR, Tzanck smear (showing multinucleated giant cells)

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4
Q

chancroid

A

haemophilus ducreyi

deep purulent painful ulcers with matted/suppurative lymphadenitis

dx with gram stain & culture, PCR

cx shows GNR in a “school of fish” chain

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5
Q

granuloma inguinale (donovaginosis)

A

klebsiella granulomatis

painless, progressive, red serpiginous ulcerative lesions without LAD

dx with gram stain and culture (difficult), BIOPSY (look for Donovan bodies - clusters of blue or black staining, bipolar chromatin condensations in large mononuclear cells)

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6
Q

Hepatitis B Infection Phases (2)

A

Proliferative - entire virion and related Ag of episomal DNA present on cell surface (HBsAg, HBcAg) in conjunction with MHC I –> CD8+ TCs destroy infected hepatocytes –> elevated ALT and AST

Integrative - DNA incorporated into host genome in surviving hepatocytes –> antiviral Abs appear and stop viral replication
*cont to have inc risk of HCC bc of integration of DNA

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7
Q

Malaria organisms

A

Plasmodium:

  1. P. falciparum
  2. P. vivax (dormant liver form = hypnozoites)
  3. P. ovale (hyponozoites)
  4. P. malariae
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8
Q

Streptococcus pneumoniae most common cause of:

A

MOPS are OPtochin Sensitive

Meningitis
Otitis media (in children)
Pneumonia
Sinusitis

Lancet-shaped, gram-positive diplococci
Encapsulated, IgA protease

sx= rusty sputum, sepsis in sickle cell anemia and splenectomy

NO VIRULENCE W/O CAPSULE

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9
Q

JONES criteria

A

dx rheumatic fever c/b immune response to M protein of S. pyogenes

Joints - polyarthritis

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10
Q

Mneumonic for penicillinase resistant penicillins

A

used to tx MSSA

CONDM

Claxicillin
Oxacillin
Naficillin 
Dicloxacillin
Methicillin
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11
Q

Anthrax exotoxin

A

Protective Antigen is needed for the other two to get into the cytosol.

Edema factor: inc cAMP by acting as adenylate cyclase causing edema and phagocyte destruction

Lethal factor: a zinc-dependent protease that inhibits MAPK signaling, causing apoptosis and multisystem physiologic disruption

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12
Q

Pertussis toxin

A

disinhibits adenylate cyclase through Gi ADP-ribosylation increasing cAMP –> edema and phagocyte dysfunction

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13
Q

Adenylate cyclase toxin

A

B. pertussis

functions as adenylate cyclase, inc cAMP, causes edema and phagocyte dysfunction

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14
Q

Botulinum toxin

A

blocks presynaptic release of ACh at NMJ –> flaccid paralysis

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15
Q

c. diff toxin A

A

recruits and activates neutrophils –> release of cytokines –> mucosal inflammation, fluid loss, diarrhea

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16
Q

c. diff toxin B

A

induces actin depolymerization –> mucosal cell death, bowel wall necrosis, pseudomembrane formation

17
Q

shiga toxin

A

halts protein synthesis by disabling 60S –> intestinal epithelial cell death and diarrhea

18
Q

pyrogenic exotoxin

A

s. pyogenes

acts as superAg inducing fever and shock

assoc with scarlet fever and strep toxic shock syndrome

19
Q

streptolysin O & S

A

s. pyogenes

damage erythrocyte membranes, causing beta-hemolysis

20
Q

major pathogen in burn patients

A

Pseudomonas aeruginosa - GNR, oxidase positive, non-lactose fermenter

tx with cefepime or ceftazidime (also some aminoglycosides, cipro, levo, aztreonam, imipenem, meropenem, ticarcillin, piperacillin

also other Gram positives and negatives

21
Q

listeria buzz word

A

tumbling motility

22
Q

adenylate cyclase activating toxins

A
Pertussis
Edema factor (anthrax)
Heat labile toxin (ETEC)
C. jejuni enterotoxin
Heat labile enterotoxin (bacillus cereus)
choleragen toxin
23
Q

guanylate cyclase activating toxins

A

Y. enterocolitica enterotoxin (Yersinia enterocolitica)

Heat stable toxin (ETEC)

24
Q

toxins that inhibit protein synthesis via ADP-ribosylation of EF-2

A
Diptheria toxin
Exotoxin A (P. aeruginosa)
25
Q

toxins that disrupt cytoskeleton

A

c. diff
- Toxin B
- cytotoxin