Staphylococcus

Question 1

What are the general characteristics of staphylococcus?

Answer 1

Gram + spherical cells in singles, pairs, and clusters; appear as ‘bunches of grapes’; non-motile and non-spore forming; no capsule; catalase producing.

Question 2

How many species are present in the genus staphylococcus?

Answer 2

Approximately 33, of which 14-17 are associated with humans.

Question 3

How were staphylococcus species initially differentiated in terms of pathogenicity?

Answer 3

By the coagulase test; those that produce coagulase are generally regarded as more dangerous.

Question 4

What differentiates staphylococcus from streptococcus?

Answer 4

Staphylococcus produces catalase, while streptococcus does not.

Question 5

What are some examples of coagulase + staphylococci?

Answer 5

S. aureus, S. pseudointermedius, S. hyicus, S. delphini, S. schleiferi.

Question 6

What are the 3 most important staphylococcus species in veterinary medicine?

Answer 6

S. aureus, S. pseudointermedius, S. hyicus.

Question 7

Are there more coagulase positive or negative staphylococcus species?

Answer 7

More coagulase negative.

Question 8

What color is S. aureus?

Answer 8

Golden-yellow colonies.

Question 9

What type of agar is used especially for S. aureus?

Answer 9

Mannitol salt agar.

Question 10

What is the habitat of S. aureus?

Answer 10

Anterior nares (carriers), skin, etc.

Question 11

What is one of the most important human and veterinary pathogens?

Answer 11

S. aureus.

Question 12

What is the primary pathogen of the staphylococcus genus?

Answer 12

S. aureus.

Question 13

What is the mode of transmission of S. aureus?

Answer 13

Traumatic introduction.

Question 14

Describe the production of S. aureus within the body.

Answer 14

Produce superficial to systemic infections.

Question 15

What are the predisposing conditions for S. aureus?

Answer 15

Chronic infections, indwelling devices, skin injuries, immune response defects.

Question 16

What are the extracellular enzymatic virulence factors of S. aureus?

Answer 16

Hemolysins, leukocidin (Panton-Valentine), enterotoxins, exfoliatin, TSST-1.

Question 17

What is the role of hemolysins as virulence factors?

Answer 17

Hemolyze RBCs.

Question 18

What are the different types of hemolysins produced by S. aureus?

Answer 18

Alpha: platelets/WBCs/tissues; Beta: sphingomyelin of RBCs; Gamma: host cell membrane; Delta: less lethal.

Question 19

What is the role of leukocidins as virulence factors?

Answer 19

Kill PMNs.

Question 20

What are the types of enterotoxins produced by S. aureus?

Answer 20

A/D: food poisoning; F: TSSAT (toxic shock syndrome toxin); B: pseudomembranous enterocolitis.

Question 21

What is caused by exfoliatin?

Answer 21

Epidermolytic toxin; phage group II staphylococci; SSS or Ritter’s Disease.

Question 22

What does TSST-1 cause?

Answer 22

Multisystem disease, high fever, hypotension, shock.

Question 23

Describe the cell structure of S. aureus from outside to inside.

Answer 23

Capsule (some strains) –> cell wall proteins –> peptidoglycan –> plasma membrane –> cytoplasm.

Question 24

What is protein A of S. aureus?

Answer 24

Protein produced which prevents interaction between opsonizing antibody and phagocyte, thus preventing phagocytosis.

Question 25

What are the different hemolytic patterns on blood agar?

Answer 25

Alpha: partial hemolysis; Beta: total hemolysis; Gamma: no hemolysis.

Question 26

What are the target cells of alpha cytotoxin?

Answer 26

RBCs, leukocytes, etc.

Question 27

What does alpha cytotoxin cause?

Answer 27

Vasoconstriction -> gangrene.

Question 28

What are the target cells of beta cytotoxin?

Answer 28

RBCs, leukocytes, etc.

Question 29

What are the target cells of delta cytotoxin?

Answer 29

RBCs, leukocytes, etc.

Question 30

What are the target cells of gamma cytotoxin?

Answer 30

RBCs.

Question 31

What are the target cells of P-V leukocidin?

Answer 31

Leukocytes.

Question 32

What do exfoliative toxins cause?

Answer 32

Scalded skin syndrome.

Question 33

TSST-1 can be described as what?

Answer 33

Superantigen.

Question 34

What are the characteristics of S. aureus enterotoxins?

Answer 34

8 antigenic types, enteritis, superantigens.

Question 35

What are the enzymes of S. aureus?

Answer 35

Coagulase: virulence marker; staphylokinase: fibrinolysin; lipase: allows colonization; hyaluronidase: CT; nuclease; penicillinase: confers resistance.

Question 36

Describe the pathogenesis of S. aureus.

Answer 36

Opportunistic pathogens, pyogenic infections, immunity: humoral and cell-mediated, hypersensitivity reactions.

Question 37

What are the characteristics of bovine peracute gangrenous mastitis?

Answer 37

- Alpha toxin causes vasoconstriction/gangrene - Teat skin encircled by black gangrene - Red or brown milk

Question 38

What are the characteristics of acute bovine mastitis?

Answer 38

- Enlarged, hot, painful quarter - Brown, serous discharge - Mediated by delta and beta toxins

Question 39

What does chronic mastitis cause?

Answer 39

Fibrosis of the udder

Question 40

What are examples of canine skin infections caused by S. aureus?

Answer 40

- Impetigo in puppies - Furunculosis - Various other pyoderma conditions

Question 41

What is udder impetigo?

Answer 41

Small, red papules observed on the udder of a cow due to S. aureus

Question 42

What skin conditions does S. aureus cause in equine?

Answer 42

Equine dermatitis/folliculitis

Question 43

What is equine botryomycosis?

Answer 43

Abscess and marked fibrous tissue reaction at the end of scirrhous cord as a result of S. aureus; result of horse castration

Question 44

What is lamb tick pyemia?

Answer 44

An infection of lambs caused by S. aureus and transmitted by the bites of ticks; also called staphylococcal pyemia

Question 45

What is the result of lamb tick pyemia?

Answer 45

Newborn lambs die of septicemia or develop signs of arthritis, meningitis, or dermatitis; causes significant economic loss through debilitation and death

Question 46

What is bumblefoot in chickens?

Answer 46

An infection caused by staphylococcus bacteria which enters the chicken's system through a cut, scratch, injury, or chafed and irritated area on the foot

Question 47

What is the result of bumblefoot?

Answer 47

The infection creates an abscess full of pus and, if left untreated, serious cases can be fatal as the infection can spread to other tissues and bones

Question 48

Which staphylococcus species is part of the natural skin flora of all canids?

Answer 48

S. pseudointermedius

Question 49

What conditions does S. pseudointermedius commonly cause in dogs?

Answer 49

Pyoderma and otitis following skin injuries

Question 50

What two groups may be carriers of S. pseudointermedius?

Answer 50

Dogs and owners

Question 51

What does S. hyicus cause?

Answer 51

Exudative epidermitis (greasy pig disease)

Question 52

What does S. hyicus predominantly affect?

Answer 52

Young pigs

Question 53

Describe the transmission of S. hyicus.

Answer 53

Breaks in the skin

Question 54

How does S. hyicus cause skin damage?

Answer 54

Exfoliative toxin

Question 55

What secondary condition does S. hyicus cause?

Answer 55

Suppurative folliculitis: excessive greasy exudate that causes skin erosion and ulceration

Question 56

What are the symptoms of greasy pig disease?

Answer 56

Greasy, peeling skin with blisters and a foul smell

Question 57

Describe the proper specimen collection and handling of staphylococcus.

Answer 57

- Samples must be taken from the actual site of infection - Prevent delay in transport of collected material from infected sites - Transport in appropriate collection device that will prevent drying and minimize growth of contaminating organisms

Question 58

What would you expect to see upon microscopic examination of a direct smear of staphylococcus?

Answer 58

- Gram + cocci - Pairs and clusters - Numerous PMNs

Question 59

Describe the colony morphology of staphylococcus.

Answer 59

- Smooth, butyrous - White to yellow and creamy - S. aureus may produce hemolysis on blood agar

Question 60

Which species of staphylococcus produce double hemolysis?

Answer 60

- S. aureus - S. pseudointermedius

Question 61

Describe the pathogenicity of staphylococcus.

Answer 61

Commensals on MM and skin, coagulase production correlates with pathogenicity

Question 62

What kind of infections do staphylococcus cause?

Answer 62

Pyogenic infections