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Microbiology 386 > Straphylococcus > Flashcards

Straphylococcus Flashcards

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1
Q

Explain the resistance of staph to the following:

  1. Heat
  2. Boiling
  3. Pasteurization
  4. Disinfectants
  5. Soap
  6. Phenol
  7. Iodine
A
  1. Heat = somewhat resistant
  2. Boiling = killed quickly
  3. Pasteurization = killed
  4. Disinfectants = somewhat resistant
  5. Soap = resistant
  6. Phenol = killed
  7. Iodine = killed
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2
Q

What is the natural habitat of staph?

A

Skin flora of most mammals and some avians

30% of humans are nasal carriers

Also present in oral cavity

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3
Q

Peptidoglycan is what percentage of the cell wall of S. aureus?

A

50-60%

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4
Q
  1. Teichoic acid in S. aureus is of the _____ type.
  2. Teichoic acid of S. epidermidis is of the ____ type.
A
  1. Teichoic acid in S. aureus is of the polyribitol type.
  2. Teichoic acid in S. epidermidis is of the polyglycerol type.
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5
Q

True or False:

  1. Antibodies agaisnt the teichoic acid component are found in low levels in normal humans.
  2. The level of antibody increases durin more severe infetions with S. aureus.
A
  1. TRUE
  2. TRUE
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6
Q

S. aureus

Teichoic acid is released from the cell and combines with antibodies present. What is this responsible for?

A

Teichoic acid is released from the cell and combines with antibodies present. This is responsible for the consumption of complement components up through C5.

(Anti-complement)

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7
Q

S. aureus:

What are the 4 biological effects of Protein A?

A
  1. Anti-complement
  2. Anti-phagocytic
  3. Chemotractic
  4. Platelet injury
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8
Q

S. aureus:

Protein A is a major component of the cell wall. In which other species of staphylococcus can this component be found?

A

S. pseudintermedius

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9
Q

S. aureus:

Protein A serves as a receptor for what?

A

Serves as a receptor for the Fc fragment of the immunoglobulin molecule

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10
Q

S. aureus:

Which component is responsible for the breakdown of bactericidal fatty acids on the skin, allowing the organism to colonize tissue?

A

Lipases

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11
Q

S. aureus alpha hemolysin:

What is the mechanism of action?

A

Heptamer forming transmembrane channels (pores)

(Causes membrane damage to a number of mammalian cell types. Produces a lot of tissue necrosis)

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12
Q

S. aureus beta hemolysin:

What is the mechanism of action?

A

Phospholipase C activity digests cells:

Hot-cold lysis (collapse of erythrocyte cell membrane at less than 10 degrees celcius)

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13
Q

What type of properties does the gamma hemolysin have in S. aureus?

A
  1. Pro-inflammatory
  2. Hemolytic
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14
Q

What type of special activity does the delta hemolysin have in S. aureus?

A

Detergent-like

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15
Q

What 2 properties does the delta hemolysin have in S. aureus?

A
  1. Lethal
  2. Dermonecrotic
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16
Q

What is the major source of variability in hemolytic activity?

A

Beta hemolysin

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17
Q

What does leukocidin work against?

A

PMNs

Macrophages

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18
Q

How does leukocidin kill PMNs and macrophages?

A

By assembling a ring structure on cell membranes and creating a pore

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19
Q
  1. What is staphylokinase?
  2. What is its function?
A
  1. Fibrinolysin
  2. Breaks down a fibrin barrier and allows the spread of the organism
20
Q

S. aureus:

What is the most important indicator of clinical significance?

A

Coagulase

(Highly correlated with pathogenicity)

21
Q

Staphylocoagulase + _____ –> staphylothrombin

Staphylothrombin –> _____ –> fibrin

A

Staphylocoagulase + prothrombin –> staphylothrombin

Staphylothrombin –> fibrinogen –> fibrin

22
Q
  1. What is hyaluronidase responsible for?
  2. When in an infection is it important?
A
  1. Responsible for the breakdown of hyaluronic acid in tissues
  2. Important early in an infection
23
Q

DNase is a nuclease capable of acting on RNA and DNA.

Nucleases are important to bacteria becuase they stimulate what?

A

Stimulate the formation of abscesses by assisting in liquefaction of pus and obtaining of nutrients

24
Q

What are the 4 superantigens of staphylococcal species?

A
  1. Enterotoxin (A-E, G and H)
  2. Staphylococcal food poisoning
  3. Toxic shock syndrome toxin - 1
  4. Exfoliative toxin (A and B)
25
Q

True or False:

  1. Not all enterotoxins are superantigens.
  2. Enterotoxins all cause gastrointestinal intoxication resulting in emesis, diarrhea, and enteritis.
A
  1. FALSE - all enterotoxins are superantigens
  2. TRUE
26
Q

How heat resistant is the staphylococcal food poisoning?

A

Withstands boiling for 30 minutes

27
Q

What symptoms are seen after ingestion of staphylococcal food poisoning?

A

Vomiting

Diarrhea

Prostration

Some fatalities

28
Q

What toxin is resposible for scalded skin syndrome seen in newborn humans?

A

Exfoliative toxin

29
Q

How does the exfoliative toxin work?

A

Causes lysis of the intracellular binding material of the epidermis

30
Q

Which superantigens have isolates from severe peracute mastitis in cattle been shown to express?

A
  1. Toxic shock syndrome toxin - 1
  2. Staphylococcus enterotoxin C
31
Q

What is most commonly isolated from wounds and abscesses on a horse?

A

Staphylococcus pseudintermedius

32
Q

What does Staph schleiferi cause in dogs?

A

Recurrent pyoderma & otitis media

33
Q

True or False:

Staph schleiferi tends to recur following a course of antimicrobial therapy.

A

TRUE

34
Q

What is responsible for the majority of subclinical or mild mastitis seen in dairy cattle?

A

Staph epidermidis

35
Q

What is thought to be the most common cause of mastitis in goats?

A

Coagulase negative staph

36
Q

Which organism is increasingly recognized as a cause of septicemia associated with intravenous catheterization & prosthetic devices?

A

Staph epidermidis

37
Q

What is the cause of exudative epidermatis in pigs?

A

Staph hyicus subspecies 1

38
Q
  1. Which organism produces 4 different exfoliative toxins?
  2. What are they?
A
  1. Staph hyicus subspecies 1
  2. A, B, C, D
39
Q
  1. Staph hyicus is also frequently related to what 2 abnormalities?
  2. Plus, in addition to exudative epidermitis, staph hyicus is also implicated as a cause of what else in pigs?
A
  1. Enlarged ureters & cystic kidneys
  2. Septic polyarthritis
40
Q

What are the hemolysis patterns for the following staph species?

  1. aureus
  2. pseudintermedius
  3. hyicus subspecies 1
  4. epidermidis
  5. schleiferi
A
  1. aureus = DZ
  2. pseudintermedius = DZ
  3. hyicus subspecies 1 = none
  4. epidermidis = none
  5. schleiferi = DZ
41
Q

What is the coagulase result for the following staph species?

  1. aureus
  2. pseudintermedius
  3. hyicus subspecies 1
  4. epidermidis
  5. schleiferi
A
  1. aureus (+)
  2. pseudointermedius (+)
  3. hyicus subspecies 1 (50/50; +/-)
  4. epidermidis (-)
  5. schleiferi (-)
42
Q

Explain phage typing:

A
  1. Staph is plated out onto an agar plate
  2. Drops of phage lysate representing bacteriophages are dropped on the agar surface
  3. Plates are incubated overnight
  4. If a bacteriophage infects the staph it will lyse it
  5. A clear plaque will result
43
Q

What are the 2 Staph aureus enzymes correlated with pathogenicity?

A

Coagulase

DNase

44
Q

The majority of antimicrobial resistance is due to the transfer of what?

A

R plasmids

45
Q

Penicillin resistant organisms are resistant due to what type of alteration?

A

Alteration in the transpeptidasei

Microbiology 386 (14 decks)

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