Staphylococcus

Question 1

Staphylococcus is the only pathogenic member of the family _____

Answer 1

Micrococcus

Question 2

Staphylococcus

Answer 2

Gram-pos, clustered cocci

• natural host: any warm blood animals
• normal flora of skin, nares, genitalia
• opportunistic pathogens

Question 3

Coagulase test

Answer 3

• coagulase positive staph are more virulent
• react with prothrombin in the serum in presence of coagulase reacting factor (CRF) = staphylothrombin
• staphylothrombin converts fibrinogen to fibrin = clotted serum

Question 4

______ serum is commonly used for a coagulase test

Answer 4

Rabbit

Question 5

Catalase positive

Answer 5

Biochemical test that differentiates staph from strep!!!

Question 6

Confirm coagulase positive with a _______

Answer 6

Tube test

Question 7

What are the 5 species of coagulase positive staphylococci?

Answer 7

• S. aureus
• S. intermedius
• S. pseudointermedius
• S. delphini
• S. schleiferi subspecies coagulans

Question 8

S. aureus

Answer 8

Natural hosts are humans (nasal), primates

• ectotypes have adapted to other animals (cattle)
• infections in all mammals and birds
• highly resistant to many antibiotics

Question 9

S. intermedius

Answer 9

Residents of skin and hair coat of carnivores, esp. in dogs

• isolated from cats, rarely horses, rodents, and birds
• phenotypically similar to S. pseudointermedius and S. delphini

Question 10

S. pseudointermedius

Answer 10

Most common residents of skin and hair coat of dogs

- often identified as S. intermedius

Question 11

S. delphini

Answer 11

Residents of dolphins

- nearest relative is S. intermedius

Question 12

S. schleiferi coagulans

Answer 12

Natural host are humans and animals

- causes external otitis in dogs

Question 13

Coagulase variable specie

Answer 13

S. hyicus

• 50/50 chance it will be coagulase positive
• commonly isolated from dog, cat, pig, cattle, poultry
• causes exudative epidermitis in pig, mastitis in cattle

Question 14

Coagulase negative staphylococcus

Answer 14

• limited to humans and/or primates, uncommon in other animals (S. epidermidis, saprophyticus, auricularis, saccharolyticus, carnosus, caseolyticus)
• isolated from all mammals (S. xylosus, simulans, sciuri)
• artiodactlya (S. lentus)
• poultry (S. gallinarum)
• goat (S. caprae)
• cattle (S. chromogenes)

Question 15

Diagnosis

Answer 15

Gram stain, catalase test, coagulase tube test, mannitol salt agar (MSA) fermentation

Question 16

Complete hemolysis

Answer 16

Alpha, delta, gamma hemolysin

Question 17

Incomplete hemolysis

Answer 17

Beta

Question 18

What are the coagulase positive species?

Answer 18

• S. aureus
• S. intermedius
• S. hyicus (variable)

Question 19

What are the slide coagulase positive species?

Answer 19

Only S. aureus

Question 20

What are the MSA growth positive species?

Answer 20

All staph species

- S. aureus, intermedius, hyicus, epidermidis

Question 21

What are the MSA fermentation positive species?

Answer 21

Only S. aureus

- key test in differentiation

Question 22

Peptidoglycan

Answer 22

Consists of N-acetyl-glucosamine (NAG) and N-acetyl-muramic acid (NAM)

• crosslinked by covalent bonds between pentapeptides and pentaglycine bridge
• confers osmotic resistance and shape

Question 23

Teichoic acid

Answer 23

Polymer of glycerol phosphate

- involves in mucosal membrane attachment

Question 24

Capsular polysaccharide

Answer 24

Inhibit chemotaxis and phagocytosis

• 4 serotypes (1, 2, 5, 8)
• used in vaccine approach: CP5, CP8, exotoxin A

Question 25

What are the 4 membrane proteins?

Answer 25

- protein A - clumping factor A and B - staphylokinase - MSCRAMMs

Question 26

Protein A

Answer 26

Small basic protein which reacts with Fc of IgG - fixes complement - antiphagocytic: promotes evasion of or interference with host immune system

Question 27

Clumping factor A and B

Answer 27

Cause of biofilm formation - binds to fibrinogen - induces adherence to host epithelial cell and platelet aggregation

Question 28

Staphylokinase (SAK)

Answer 28

Activates plasminogen to plasmin --> plasmin digests fibrin clot - serine protease activity: degrades C3b (complement factor) and IgG

Question 29

MSCRAMMs

Answer 29

Microbial surface components recognizing matrix molecules - induce adherence and invasion (internalization) to host epithelial cell - fibronectin binding protein and alpha5beta1 integrin - autolysin (Atl) and heat shock protein (Hsc70) - clumping factor B and cytokeratins - protein A and tumor necrosis factor alpha receptor

Question 30

Hemolysins (hemotoxins)

Answer 30

Clear or complete hemolysis - alpha: leukocidal, cytocidal, vasoconstriction, necrosis (skin and udder) - delta: phospholipase, leukocidal, necrosis - gamma or epsilon: weal hemolysis Incomplete hemolysis - beta (sphingomyelinase): enzymatic damage to RBC membrane in vitro, results in discolorization but not lysis

Question 31

Leukocidins

Answer 31

- cytotoxic: leukocytes (granulocyte, monocyte, macrophage) - common in community acquired S. aureus - causes necrotizing pneumonia

Question 32

Exfoliative toxins

Answer 32

Cause blistering skin disease: scalded skin syndrome | - cleave desmoglein-1

Question 33

All staphylococcal enterotoxins are _____

Answer 33

Superantigen - directly binds to TCR and MHC 2 - massive T cell activation - massive cytokine production leading to toxic shock

Question 34

What staphylococcal enterotoxins cause food poisoning?

Answer 34

A, B, C, D, E, G, and I | - emesis, diarrhea, fever, abdominal cramping

Question 35

Urease and phosphatase

Answer 35

In cystitis: hydrolyze urea --> increasing ammonia --> increase urine pH ---> crystallization of struvite and apatite = calculi formation

Question 36

Most staph infections are ____ in origin

Answer 36

Endogenous - naturally colonized 30-40% population - non invasive colonization and adhesion to surface are common - may act as opportunistic or secondary invaders

Question 37

Quorum sensing

Answer 37

Regulating virulence factors by signaling molecules, autoinducing peptide: produced by agr locus - low AIP density: expression of adhesion molecules such as MSCRAMMs - high AIP density: expression of toxins and enzymes

Question 38

Staph usually does not cause _____

Answer 38

Any unique diseases or conditions - pyogenic host response most common - abscesses and septicemias in many species

Question 39

Canine staph infection

Answer 39

Common infections with S. intermedius followed by S. aureus - pyodermas: superficial, deep, juvenile (usually secondary), hypersensitivity/allergic dermatitis, demodicosis, flea bites

Question 40

Dairy cattle and sheep staph infection

Answer 40

Leading cause of contagious mastitis

Question 41

Pig staph infection

Answer 41

S. hyicus | - exudative seborrheic dermatitis/greasy pig disease

Question 42

Botryomycosis

Answer 42

S. aureus | - granules with chronic granulomatous lesions of udder in mare, cow, sow, and spermatic cord of horses

Question 43

Tick pyemia

Answer 43

Type of septicemia that leads to widespread abscesses of lamb

Question 44

Purulent synovitis and bumblefoot of birds

Answer 44

S. aureus - osteitis and tenosynovitis (proliferation of synovial membrane producing solid tumor-like mass) are common extensions of bumble foot

Question 45

No single virulence factor has been identified that can be used to make a _______

Answer 45

Vaccine

Question 46

Commercial products are commonly used to

Answer 46

Prevent bovine mastitis

Question 47

Treatments

Answer 47

Antimicrobials: use results of antibiotic sensitivity test, bactericidal drugs are best - penicillin G if sensitive - keflex or cefadroxil - clavamox - ciprofloxacin