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Flashcards in Straphylococcus Deck (45):
1

Explain the resistance of staph to the following:

  1. Heat
  2. Boiling
  3. Pasteurization
  4. Disinfectants
  5. Soap
  6. Phenol
  7. Iodine

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

2

What is the natural habitat of staph?

Skin flora of most mammals and some avians

30% of humans are nasal carriers

Also present in oral cavity

3

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

50-60%

4

  1. Teichoic acid in S. aureus is of the _____ type.
  2. Teichoic acid of S. epidermidis is of the ____ type.

  1. Teichoic acid in S. aureus is of the polyribitol type.
  2. Teichoic acid in S. epidermidis is of the polyglycerol type.

5

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.

  1. TRUE
  2. TRUE

6

S. aureus

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

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)

7

S. aureus:

What are the 4 biological effects of Protein A?

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

8

S. aureus:

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

S. pseudintermedius

9

S. aureus:

Protein A serves as a receptor for what?

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

10

S. aureus:

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

 

Lipases

11

S. aureus alpha hemolysin:

What is the mechanism of action?

Heptamer forming transmembrane channels (pores)

 

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

12

S. aureus beta hemolysin:

What is the mechanism of action?

Phospholipase C activity digests cells:

 

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

13

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

  1. Pro-inflammatory
  2. Hemolytic

14

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

Detergent-like

15

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

  1. Lethal 
  2. Dermonecrotic 

16

What is the major source of variability in hemolytic activity?

Beta hemolysin

17

What does leukocidin work against?

PMNs

Macrophages

18

How does leukocidin kill PMNs and macrophages?

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

19

  1. What is staphylokinase?
  2. What is its function?

  1. Fibrinolysin
  2. Breaks down a fibrin barrier and allows the spread of the organism

20

S. aureus:

What is the most important indicator of clinical significance?

Coagulase

(Highly correlated with pathogenicity)

21

Staphylocoagulase + _____ --> staphylothrombin

Staphylothrombin --> _____ --> fibrin

Staphylocoagulase + prothrombin --> staphylothrombin

Staphylothrombin --> fibrinogen --> fibrin

22

  1. What is hyaluronidase responsible for?
  2. When in an infection is it important?

  1. Responsible for the breakdown of hyaluronic acid in tissues
  2. Important early in an infection

23

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

Nucleases are important to bacteria becuase they stimulate what?

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

24

What are the 4 superantigens of staphylococcal species?

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

25

True or False:

  1. Not all enterotoxins are superantigens.
  2. Enterotoxins all cause gastrointestinal intoxication resulting in emesis, diarrhea, and enteritis.

  1. FALSE - all enterotoxins are superantigens
  2. TRUE

26

How heat resistant is the staphylococcal food poisoning?

Withstands boiling for 30 minutes

27

What symptoms are seen after ingestion of staphylococcal food poisoning?

Vomiting

Diarrhea

Prostration

Some fatalities

28

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

Exfoliative toxin

29

How does the exfoliative toxin work?

Causes lysis of the intracellular binding material of the epidermis

30

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

  1. Toxic shock syndrome toxin - 1
  2. Staphylococcus enterotoxin C

31

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

Staphylococcus pseudintermedius

32

What does Staph schleiferi cause in dogs?

Recurrent pyoderma & otitis media

 

33

True or False:

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

TRUE

34

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

Staph epidermidis

35

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

Coagulase negative staph

36

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

Staph epidermidis

37

What is the cause of exudative epidermatis in pigs?

Staph hyicus subspecies 1

38

  1. Which organism produces 4 different exfoliative toxins?
  2. What are they?

  1. Staph hyicus subspecies 1
  2. A, B, C, D

39

  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?

  1. Enlarged ureters & cystic kidneys
  2. Septic polyarthritis

40

What are the hemolysis patterns for the following staph species?

  1. aureus
  2. pseudintermedius
  3. hyicus subspecies 1
  4. epidermidis
  5. schleiferi

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

41

What is the coagulase result for the following staph species?

  1. aureus
  2. pseudintermedius
  3. hyicus subspecies 1
  4. epidermidis
  5. schleiferi

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

42

Explain phage typing:

  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

What are the 2 Staph aureus enzymes correlated with pathogenicity?

Coagulase

DNase

44

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

R plasmids

45

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

Alteration in the transpeptidasei