Staphylococcus

Question 1

What does the genus Staphylococcuslook like on a gram stain?

Answer 1

gram positive, clustering cocci

Question 2

Compare the shapes of Staphylococcusvs. Micrococcus.

Answer 2

Staphylococcus is spherical, Micrococcus is not always spherical

Question 3

Compare the gram reactions of Staphylococcusvs. Micrococcus.

Answer 3

Staphylococcus is gram positive, Micrococcus decolorizes readily

Question 4

Compare the colony colors of Staphylococcusvs. Micrococcus.

Answer 4

Staphylococcus has white to golden colonies, Micrococcus has clear to yellow colonies

Question 5

Compare the hemolysis patterns of Staphylococcusvs. Micrococcus.

Answer 5

Staphylococcus has some hemolytic species, Micrococcus is nonhemolytic

Question 6

Compare the O2 requirements of Staphylococcusvs. Micrococcus.

Answer 6

Staphylococcus is faculative, Micrococcus is an obligate aerobe

Question 7

Compare the salt tolerance of Staphylococcusvs. Micrococcus.

Answer 7

Staphylococcus has good salt tolerance, Micrococcus has poor salt tolerance

Question 8

What inactivates lipases?

Answer 8

there is a prophage that has inserted into the lipase gene and inactivates it

Question 9

What is alpha hemolysis?

Answer 9

the incomplete lysis of RBC’s

Question 10

What is beta hemolysis?

Answer 10

the complete lysis of RBC’s

Question 11

What is gamma hemolysis? And do we care?

Answer 11

no hemolysis - no we use the term ‘no hemolysis’

Question 12

What type of hemolysin causes alpha hemolysis?

Answer 12

beta

Question 13

What type of hemolysin causes beta hemolysis?

Answer 13

alpha

Question 14

If both hemolysin are present, then what pattern of hemolysis occurs?

Answer 14

double zone hemolysis

Question 15

What is shown here?

Answer 15

double zone hemolysis

Question 16

What is the structure of staphylococcal alpha hemolysin?

Answer 16

it assembles as a mushroom shaped heptamer with a central channel

Question 17

What does staphylococcal alpha hemolysin do?

Answer 17

it forms poers in cell membranes and produces a lot of tissue necrosis

Question 18

What is the function of beta hemolysin?

Answer 18

it has phospholipase C activity - it causes the collapse of the erythrocyte cell membrane

Question 19

T/F: Gamma hemolysin is only one protein.

Answer 19

False - it is made up of three proteins; A, B, and C

Question 20

What properties does gamma hemolysin have?

Answer 20

inflammatory properties

Question 21

What type of hemolysis does delta hemolysin have?

Answer 21

complete

Question 22

What type of action does delta hemolysin have?

Answer 22

detergent-like action

Question 23

What is the function of leukocidin and what is it active against?

Answer 23

it kills white cells - only active against neutrophils and macrophages

Question 24

What are PNAGs?

Answer 24

poly-N-acetylglucosamines - extracellular polysaccharides mediating biofilm formation

Question 25

What is staphylokinase and what does it do?

Answer 25

a spreading factor that breaks down fibrin and allows the organism to spread

Question 26

What is the most important test for pathogenicity in staphylococci?

Answer 26

the coagulase test - free and bound tests

Question 27

How does the free coagulase test work?

Answer 27

it converts fibrinogen to fibrin

Question 28

How does the bound coagulase test work?

Answer 28

it agglutinates the organism in the presence of plasma

Question 29

What is hyaluronidase?

Answer 29

a spreading factor that breaks down hyaluronic acid

Question 30

What are the three superantigens?

Answer 30

enterotoxins, toxic shock syndrome toxin 1 (TSST1), and exfoliative toxins

Question 31

What are the type of enterotoxins?

Answer 31

A-E, G and H

Question 32

What are enterotoxins commonly a factor in (illness/disease) ?

Answer 32

food poisoning

Question 33

Are enterotoxins heat resistant or heat susceptable?

Answer 33

heat resistant

Question 34

What disease is exfoliative toxins commonly associated with?

Answer 34

scalded skin syndrome

Question 35

Generally, what do the colonies of S. aureus look like?

Answer 35

they are gold colonies but can be white

Question 36

What is S. aureusresistant to?

Answer 36

heat and disinfectants

Question 37

What is 50 to 60 percent of the cell wall of S. aureusmade up of?

Answer 37

peptidoglycan

Question 38

What is the role of teichoic acids in S. aureus?

Answer 38

it is released from the organism to tie up antibody from the host

Question 39

What Staphylococcus species is protein A found in?

Answer 39

S. aureus and S. pseudintermedius

Question 40

What is the role of protein A?

Answer 40

it binds to antibody via the Fc region and the bacteria then coat themselves with the host antibody making the host continually susceptible to re-infection

Question 41

Does S. aureus have a capsule?

Answer 41

yes, but it is only present in-vivo and is quickly lost on culture

Question 42

What is the role of lipases in S. aureus?

Answer 42

they breakdown bactericidal fatty acids on the skin and is responsible in large part for the ability of the organism to colonize this tissue

Question 43

What disease in cattle, sheep, and goats is associated with S. aureus?

Answer 43

mastitis

Question 44

What is found in some isolates of S. aureus associated with cattle?

Answer 44

TSST1 (toxic shock syndrome toxin)

Question 45

What does S. aureuscause in dogs?

Answer 45

skin infections, pustular dermatitis, wound infections, otitis, urogenital (especially cystitis), acral lick dermatitis, and mastitis

Question 46

What does S. aureus cause in cats?

Answer 46

abscesses, wounds of conquest, urinary infections

Question 47

What does S. aureus cause in horses?

Answer 47

wounds and abscesses

Question 48

What is about 80% of staph infections in horses?

Answer 48

S. pseudintermedius

Question 49

What does S. aureus cause in avian species?

Answer 49

gangrenous or necrotic dermatitis, bumblefoot, and occasional ocular infections

Question 50

What human are some human staph infections?

Answer 50

conjunctivitis, bolis, otitis, sinusitis, cystitis, osteomyelitis, bacteremia, septicemia, meningitis, toxic shock syndrome, and food poisoning

Question 51

What leukocyte is very important to immunity in S. aureus?

Answer 51

neutrophils

Question 52

What are the subspecies of Staphylococcus schleiferi?

Answer 52

shleiferi and coagulans

Question 53

What diseases are associated with Staphylococcus schleiferi?

Answer 53

pyoderma, otitis externa

Question 54

Is S. epidermidis coagulase negative or positive?

Answer 54

negative

Question 55

What diseases are associated with Staphylococcus epidermidis?

Answer 55

mild or subclinical mastitis in dairy cattle and goats, skin infections, and septicemia in humans associated with intravenous catheters

Question 56

What disease is associated with Staphylococcus hyicus subspecies 1?

Answer 56

exudative epidermitis (greasy pig disease)

Question 57

What does S. hyicusdo to the epidermis in pigs?

Answer 57

separation of epidermal cells, exfoliation, erythema, and outpouring of serum

Question 58

How is S. hyicus prevented in pigs?

Answer 58

they are vaccinated or antibiotics are used

Question 59

What disease is associated with Staphylococcus hyicus subspecies 2?

Answer 59

mastitis in dairy cattle

Question 60

What disease is S. sciuri and S. xylosus associated with?

Answer 60

low-grade mastitis in dairy cattle

Question 61

What disease is S. saprophyticus associated with?

Answer 61

cystitis

Question 62

What is S. gallinarum associated with?

Answer 62

poultry - it is commonly found on skin

Question 63

What tests are used to differentiate staphylococci species?

Answer 63

hemolysis, coagulase, VP test, carbohydrate fermentation tests, MALDI-TOF MS, and phage typing