Staphylococcus

Question 1

What are some general Staphylococcus characteristics?

Answer 1

1. Gram + aerobic cocci
2. “Grape-like clusters”
3. Opportunistic pathogens
4. Cause “pyogenic infections”
5. Part of normal flora of skin and exposed mucosa
6. Typical lesions are suppurative infections

Question 2

What is the coagulase test?

Answer 2

Defines the most virulent species

Question 3

What are 3 coagulase positive staphylococcus of importance?

Answer 3

1. S. aureus
2. S. hyicus
3. S. pseudintermedius

Question 4

What is the pathogenesis of Staphylococcus?

Answer 4

Colonizes breaks in host skin or mucosa

Readily overcomes innate immune responses

Inflammation

Destroys Leukocytes through exotoxins

Classic agents of surgical wound infections

Question 5

What is the type of pathology for Staphylococcus?

Answer 5

Pus formation

Abscess formation and local necrosis

Acute infections, sometimes chronic

Question 6

What is S. aureus?

Answer 6

Pyogenic opportunist infection

Skin & wound infections producing local necrosis & pus

UTI (dogs, cats, humans), Mastitis (bovine)

Food-borne intoxications, TSS (humans)

Contagious & seen in nosocomial infections

Question 7

What is S. pseudointermedius?

Answer 7

“The canine S. aureus”

Opportunist pathogen of dogs

Staphylococci associated canine pyoderma

Question 8

What is S. hyicus?

Answer 8

Causes greasy pig disease (exudative epidermis) in 1-6 week pigs piglets

Question 9

What is “bumblefoot”?

Answer 9

Found in poultry

Caused by S. aureus

Question 10

What is Botryomycosis?

Answer 10

Seen in Lab animals primarily (rodents), humans and horses

Chronic pyogranulomatous inflammation

Caused by S. aureus

Not a superficial skin infection

Question 11

What are toxin mediated diseases in humans?

Answer 11

Caused by effect of superantigens

1. Staphylococcal toxic shock syndrome (TSS)
2. Stahylococcal foodpoisoning (enterotoxin)
3. Staphylococcal scalded skin syndrome in humans (exfoliative toxins)

Question 12

What is the key point of Coagulase negative Staphylococcus spp.?

Answer 12

Rarely cause disease in immunocompetent animals

Question 13

What are 3 lab dx used for staphylococcus?

Answer 13

1. Cytology or Gram staining
2. Culture
3. PCR

Question 14

List the treatment methods of staphylococcus

Answer 14

1. Treat w/antimicrobial agents and elimination of primary/predisposing cause
2. Antimicrobial susceptibility testing always recommended
3. Always look for possible underlying disease or predisposing factors to infection

Question 15

What resistance should be considered when deciding treatment for staphylococcus infections?

Answer 15

All staphylococcus isolates, which are macrolide resistant, should be considered Clindamycin resistant unless otherwise confirmed by D-test

Question 16

How would you treat Pyoderma?

Answer 16

Topical vs. Systemic

Benzoyl peroxide, ethyl lactate, chlorhexidine (antibacterial)

Mupirocin (Ab)

Cleansing and antimicrobial shampoo

Diluted bleach

Question 17

What is the key point in antimicrobial resistance of staphylococcus?

Answer 17

MRSA & MRSP are rapidly emerging in animals, which my reflect lax infection control

Question 18

What is important about Methicillin resistance?

Answer 18

Methicillin resistance is mediated by mega gene resulting in altered penicillin binding proteins (PB2a)

MRS often exhibits multi drug resistance

Question 19

How would you prevent mastitis?

Answer 19

Hygiene practices

Clean milking equipment

Tx w/antimicrobials - “dry cow tx”

Question 20

What is the most common site of colonization?

Answer 20

Nares

Question 21

What is the most common source of transmission?

Answer 21

Hands