STEP 1 Gram Positive Bacteria 1 Flashcards

1
Q

Staphylococcus Aureus

  1. Shape and stain
  2. Virulence Factor and how it works
A

Gram positive cocci in clusters
Catalase +
Coagulase +
Protein A Virulence factor–binds Fc-IgG, inhibits complement activation and phagocytosis

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2
Q

Staph aureus causes which types of diseases (3)

A

Inflammatory disease, toxin-mediated disease, MRSA

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3
Q

Staph aureus inflammatory infections (5)

A
  1. Skin infections
  2. Organ abscesses
  3. Pneumonia (usually after influenza virus)
  4. Endocarditis
  5. Osteomyelitis
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4
Q

Staph aureus toxin-mediated disease (3)

A
  1. Toxic shock syndrome (TSST-1)
  2. Scalded skin syndrome
  3. Rapid-onset food poisoning (enterotoxins)
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5
Q

How is MRSA resistant to PCN and nafcillin?

A

Altered penicillin-binding proteins

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6
Q
How does TSST work?
Symptoms (5 total but 3 major)
Predisposition from (2)
A

Superantigen that binds MHC II and T-cell receptor, resulting in polyclonal T-cell activation.
Causes: fever, vomiting, desquamination, shock, and end-organ failure
Predisposed by vaginal or nasal tampons

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7
Q

S. aureus food poisoning:
ingestion of?
incubation?
toxin stability?

A

Ingestion of pre-formed spores
Short incubation (2-6hours)
Toxin is heat stable so NOT destroyed by cooking

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8
Q

Staphylococcus epidermis characteristics

gram, shape, catalase, sensitivity, coagulase

A

Gram + Cocci in clusters
Catalase +
Novobiocin sensitive
coagulase -

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9
Q

Staph epidermis commonly infects what? It’s something nearly every patient in a hospital has

A

Infects prosthetic devices and IV catheters by producing adherent biofilms

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10
Q

Staphylococcus saprophyticus

gram, shape, catalase, coagulase, resistance (this is what sets it apart from s. epidermis)

A

Gram + cocci
Catalase +
Coagulase -
Novobiocin resistant

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11
Q

Staphylococcus saprophyticus:

2nd most common cause of what?

A

Second most common cause of UTI in young women. First would be E.Coli

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12
Q

Streptpcoccus pneumoniae

gram, shape, catalase, hemolysis, capsule?, sensitivity, GI susceptibility, protease

A
Gram + cocci in chains (lancet shaped diplococci)
Catalase -
Alpha hemolysis
Capsule present
Optochin sensitive
Bile soluble (lysed by bile)
IgA protease
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13
Q

Streptococcus pneumoniae is most common cause of what? (4)

A

Meningitis
Otitis Media (in children)
Pneumonia
Sinusitis

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14
Q

Strep pneumoniae:
sputum color
causes what is sickle cell patients?
Associated with what procedure?

No virulence without?

A
  1. Rusty Sputum
  2. Sepsis in sickle cell anemia
  3. Splenectomy (encapsulated organism)

No virulence without capsule

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15
Q

What is Staphylococcus saprophyticus’s nickname?

A

Honeymooner’s UTI due to its association with sex

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16
Q

Viridans streptococci (2)

A
  1. Streptococci mutans

2. Streptococci sanguinins

17
Q

Viridans streptococci:
gram, shape, catalase, and hemolysis
normal colonization location

A

Gram positive cocci
Catalase negative, coagulase negative
Alpha-hemolytic
Colonize the oropharynx

18
Q

S. mutans causes what?

A

Dental caries

19
Q

S. sanguinins causes what? How?

A

Subacute bacterial endocarditis.

S. Sanguinins makes dextrans, which bind to fibrin-platelet aggregates on damaged heart valves

20
Q

Viridans streptococci are resistant to which chemical? How is this helpful when dealing with S. pneumo?

A

Optochin resistant.

S. pneumo is optochin sensitive

21
Q
Streptococcus pyogenes (group A strep)
gram, shape, catalase, hemolysis, coagulase
A

Gram positive cocci
Catalase and coagulase negative
B-hemolysis (clear hemolysis)

22
Q

S. pyogenes causes three types of infections

A
  1. Pyogenic
  2. Toxigenic
  3. Immunologic
23
Q

S. pyogenes pyogenic infections (3)

A

pharyngitis, cellulitis, and impetigo

24
Q

S. pyogenes toxigenic infections (3)

A

scarlet fever, toxic shock-like syndrome, necrotizing fasciitis

25
S. pyogenes immunologic consequences (2)
rheumatic fever and glomerulonephritis
26
S. pyogenes (GAS) is sensitive to...
bacitracin
27
How does rheumatic fever come about?
Antibodies to M protein (of GAS) enhance host defenses against S. pyogenes but can give rise to rheumatic fever via cross reactivity against heart muscle
28
What is the JONES criteria for rheumatic fever?
``` J-Joints (polyarthritis) O-that's supposed to be a heart (carditis) N-Nodules (subcutaneous) E-Erythema marginatum S-Sydenham chorea ```