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Logan Step 1 High Yield > General Micro > Flashcards

General Micro Flashcards

1
Q

What is an exotoxin?

  • GN, GP or both?
  • Where are genes that code for exotoxins?
  • Effects // our response
A

GP + GN substance that is SECRETED from cells

  • Genes are located on plasmids or bacteriophage
  • SUPER toxic -> cause recognizable diseases
  • We make Abs against exotoxins = basis of vaccine
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2
Q

What is an endotoxin?

  • GN, GP, or both?
  • Where are the genes that code for endotoxins?
  • Effects
A

LPS on GN cell membrane = normal part of the cell that fragments off

  • Genes in bacterial chromosome
  • Causes fever, hypotension = shock, DIC
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3
Q

ENDOTOXIN mnemonic for the mechanism of endotoxin

A 
Edema (from C3a)
NO (from macrophages -> hypotension)
DIC/death (due to tissue factor)
Outer membrane (found here on GN)
TNFa (causes fever + hypotension)
O-antigen
Xtremely heat stable 
IL 1 (causes fever)
Neutrophil chemotaxis (b/c C5a)
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4
Q

Diptheria toxin mechanism + presentation

A

X elongation factor
Pharyngitis:
- Pseudomembranes = white plaques
- Severe lymphadenoapthy

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5
Q

Pseudomonas: toxin + mechanism + presentation

A

Exotoxin A
X elongation factor
Causes host cell death

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6
Q

Shigella toxin: mechanism + presentation

A

X 60s ribosome subunit

  1. Inflamed intestines -> bloody diarrhea
  2. HUS
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7
Q

EHEC: toxin + mechanism + presentation

A

Shiga-like toxin -> difference is that EHEC does not invade host cells
X 60s ribosome subunit
HUS

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8
Q

B.anthracis: toxin + mechanism + presentation

A

Edema toxin
More cAMP
Causes the red area around the black eschar in cutaneous anthrax

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9
Q

Cholera toxin: mechanism + presentation

A

More cAMP -> more Cl- secreted into the gut (water follows)

Rice water diarrhea

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10
Q

ETEC: 2 toxins + mechanism + presentation

A
  1. Heat labile toxin = more cAMP = Cl secretion @ gut, water follows
  2. Heat stable toxin = more cGMP = less NaCl reabsorbed = water follows
    “Labile in the Air (adenylate cyclase) stable on the Ground (guanylate)
    WATERY DIARRHEA
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11
Q

Most exotoxins are A-B toxins. What does that mean?

A

B = binding, binds to host cell receptor -> endocytosis
A = active, attaches ADP-ribosyl to disrupt host cell proteins
Often increase cAMP

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12
Q

Pertussis toxin: mechanism + presentation

A

No Gi -> more cAMP

Whooping cough

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13
Q

Clostridium tetani: toxin + mechanism + presentation

A 
Tetanospasmin 
Cleave SNARE - no vesicle fusion 
X GABA or glycine release = inhibitory 
@ Renshaw cells in spinal cord
1. Spasm
2. Risus sardonicus
3. Lockjaw
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14
Q

Botulinum toxin: mechanism + presentation

A

X SNARE -> no vesicle release
X ACh @ NMJ
= Flaccid paralysis
Floppy baby

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15
Q

Clostridium perfringens: toxin + mechanism + presentation

A

Alpha toxin = lecithinase = enzyme that causes tissue necrosis

  1. Gas gangrene
  2. Double zone hemolysis on blood agar
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16
Q

Strep pyogenes: toxin + mechanism + presentation

A

Streptolysin O
RBC lysis = why S.py is B hemolytic
Abs made against this toxin = ASO Abs
- Dx for rheumatic fever

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17
Q

S.aureus: toxin + mechanism + presentation

A 
Toxic shock syndrome toxin
IL1, IL2, IFNg, TNFa
1. Toxic shock syndrome
2. Scalded skin syndrome
3. Food poisoning
18
Q

What is the other toxin S.pyogenes (besides streptolysin O) can release to cause toxic shock syndrome?

A

Exotoxin A

19
Q

Do GN or GP have T3 secretion system?

A

GN

20
Q

What is unique to GN cell walls

A 
Capsule (GN + GP)
**Outer membrane made of LPS/endotoxin (GN only)
**Space w/ peptidoglycan + B lactamases (GN only)
Cytoplasmic membrane (GN + GP)
21
Q

Mnemonic for bugs that don’t gram stain well:

“These Microbes May Lack Real Color”

A 
Treponema
Mycob - use carbolfuschin
Mycoplasma 
Legionella - use silver stain
Rickettsia
Chlamydia
22
Q

What 2 bugs get cultured on Thayer-Martin agar? Mnemonic for what is in the medium: “Very Typically Cultures Neisseria”

A 
N. gonorrhoeae + meningitidis
Vanco
Trimethoprim
Colistin 
Nystatin
23
Q

Where does TB reactivate if pt is put on immune suppression? Why does this make sense?

A

@ apices of lung
= Highest PO2
Myco TB is aerobic bug

24
Q

What antibiotic class doesn’t work against anaerobes?

A

Aminoglycosides

Require O2 to enter bacterial cell wall

25
Q

Mnemonic for obligate intracell bugs: Stay inside cells when it is “Really CHilly and COld”

A

Richettsia
CHlamydia
COxiella
Intracell b/c rely on host ATP

26
Q

Mnemonic for facultative intracell bugs: “Some Nasty Bugs May Live FacultativeLY”

A 
Salmonella
Neisseria
Brucella
Mycob
Listeria
Fracisella 
Legionella 
Yersinia
27
Q

Which pts are at high risk for infection by encapsulated bacteria?

A

W/o spleen!

28
Q

Why conjugated vaccines?

A

Conjugate = antigen + carrier protein

B/c polysaccharide antigen of bacteria w/ capsules can’t be presented alone to T cells

29
Q

Mnemonic for encapsulated bacteria: SHiNE SKiS

A 
Strep pneumo
Haemophilus influ
Neisseria men
E.coli
Salmonelaa
Kleb
grp B Strep
30
Q

Mnemonic for +urease: CHuck norris hates PUNKSS

A 
Crypto 
H.pylori
Proteus
Ureaplasma 
Nocardia
Kleb
S.epi
S.sapro
31
Q

Disease that is NADPH oxidase def

A

Chronic granulomatous disease

Much watch for catalase + bugs

32
Q

Mnemonic for +catalase: Cats Need PLACESS to hide

A 
Catalase 
Nocardia
Pseudo
Listeria
Aspergillus
Candida
E.coli
Staphylococci
Serratia
33
Q

Bacteria that makes yellow sulfur granules on plates

A

Actinomyces

“Israel has yellow sand”

34
Q

Bacteria that has gold/yellow color on plates

A

S.aureus

Aureus = gold in Latin

35
Q

Bacteria that has GREEN color on plates

A

Psudomonas

36
Q

Bacteria that has red pigment on plates

A

Serratia (red dino!)

37
Q

What is bacterial transformation?

A

Bugs that take up naked DNA
Into DNA via homologous recomb (+/- MMR)
Ex: gaining amplicin resistance genes

38
Q

What is bacterial transposition?

A

Transposon = DNA = jumps in chromosomes

Gene transfer from plasmid to chromosome

39
Q

What’s bacterial conjugation?

  1. F+ x F-
  2. Hfr x F-
A

Sex pilus transmission of drug resistant genes
1. F+ = has plasmid
Pilis transfers plasmid ONLY (no chromosomal genes) to F-
2. Plasmid + some flanking chromosomal DNA replicate in Hfr
All that goes into F-

40
Q

What is transduction?

  1. Generalized
  2. Specialized
A

Bacterial DNA moves via virus

  1. “Packaging” = lytic phage into bacteria -> cleave DNA -> viral capsid -> phages infections another bacteria + transfers the genes
  2. “Excision” = phage DNA takes bacterial genetic infor the flanked its true info (toxin genes)

Logan Step 1 High Yield (7 decks)

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