Staphylococcus

Question 1

Antimicrobial susceptibility

Answer 1

Test to see if susceptible to antibiotis

Question 2

Who standardizes antimicrobial susceptibility

Answer 2

CSLI and VAST

Question 3

Approved methods for antimicrobial sensitivity

Answer 3

-Disk diffusion
-Broth dilution

Question 4

Disk diffusion

Answer 4

Put culture on agar and incubate and look at zones of inhibition (qualitative)

Question 5

Broth dilution

Answer 5

can be macrobroth or microbroth. Can measure MBC and MIC with this method (quantitave)

Question 6

Breakpoints

Answer 6

MIC selected to predict clinical outcome intermediate stage

Question 7

Breakpoints based on

Answer 7

-Pop distribution of clinical isolates
-Achievable serum concentration
-Clinical efficacy studies

Question 8

Gram stain

Answer 8

Gram +

Question 9

Morphology

Answer 9

Cocci in clusters (looks like bunch of groups)

Question 10

Oxygen requirements

Answer 10

Facultative

Question 11

Special characteristic

Answer 11

Can grow in high salt concentrations

Question 12

Pyogenic cocci

Answer 12

Staph and strept

Question 13

Catalase test

Answer 13

Can used to differentiate Staph (positive) and strep (negative)

Question 14

Most common species

Answer 14

aureus. Infects everyone

Question 15

Cattle

Answer 15

Mastitis

Question 16

Chickens

Answer 16

Dermatitis, arthritis, bumble foot

Question 17

Pigs

Answer 17

Skin infections and septicemia

Question 18

Dogs and cats

Answer 18

Pyoderma, otitis externa, endometriosis

Question 19

Horses

Answer 19

Dermatitis, cellulitis

Question 20

Important species

Answer 20

-pseudintermedius
-hyicus
-intermedius
-epidermis

Question 21

Which staph species is non hemolytic and coagulase negative

Answer 21

hyicus

Question 22

Double zone hemolysis

Answer 22

-inside zone (complete hemolysis from alpha)
-Outer layer (partial hemolysis from beta)

Question 23

Medium to determine S. aureus

Answer 23

Mannitol salt agar( others can’t ferment mannitol) turns it yellow

Question 24

Habitat

Answer 24

Skin and mucous membranes expecially nostrils. In every animal

Question 25

Virulence factors

Answer 25

-Cell associated components -Exoenzymes -Exotoxins

Question 26

Cell associated components

Answer 26

-Surface proteins: protein A and adhesins -To protect from immune response

Question 27

Exoenzymes

Answer 27

-Coagulase -Lipase -Hyaluronidase -Proteases

Question 28

Exotoxins

Answer 28

-Toxic shock syndrome -Enterotoxins -Exfoliative toxins -Hemolysins (4)

Question 29

Enterotoxins

Answer 29

-Food borne infections -Superantigens -Heat stable and cannot inactivate by cooking -Stimulates vagus nerve to induce vomiting and abdominal pain

Question 30

Staph food poisoning

Answer 30

-Salty foods like ham -Milk and cheese -From food workers who carry it -Very fast onset, lasts 1-3 days

Question 31

Alpha hemolysis

Answer 31

Incomplete no clear zone looks green.

Question 32

Beta hemolysis

Answer 32

Complete hemolysis clear zone

Question 33

Alpha hemolySIN

Answer 33

Produces complete hemolysis (beta) form pore

Question 34

Beta hemolySIN

Answer 34

incomplete hemolysis (alpha) damages membranes with sphingomyelin. Increases activity in cold temp

Question 35

Gamma hemolysin

Answer 35

Leukotoxin, pore forming not in all strains

Question 36

Pathogenesis

Answer 36

-Pus forming lesions usually skin -Predisposing factors is injury to the skin or immune suppression

Question 37

Diseases in animals

Answer 37

-Mastitis in dairy cows -Dermatitis and joint infections in chickens -Pyoderma in dogs -Exudative dermatitis in pigs (greasy pig syndrome)

Question 38

Mastitis

Answer 38

-Enters via teat and travels up teat canal to mammary tissue and bind to cells -Can be mild to gangrenous -Neutrophils cause clots and edema as well as clots -Contagious

Question 39

Diagnosing bovine mastitis

Answer 39

Isolation of coagulase-positive or negative staph from bulk tank milk samples. Important to diagnose subclinical on somatic cell count or total bacterial count

Question 40

Treatment of mastitis

Answer 40

-Intramammary administrations of antibiotics -Beta lactamase resistant antibiotics

Question 41

Prevention of mastitis

Answer 41

Dry cow therapy. Give antibiotics during dry period. No vaccines

Question 42

Disease in chickens

Answer 42

-Dermatitis -Osteomyelitis -Arthritis -Synovitis -Bactermia or septicemia

Question 43

Bumble foot

Answer 43

swollen feet in chicken from S. aureus

Question 44

Exudative dermatitis in pigs

Answer 44

Greasy pig syndrome. Caused by S. hyicus. Come from breach in epidermis (opportunistic pathogen). Starts in face and moves back. Excess secretion from sebaceous glands. Get death form dehydration

Question 45

Diagnosing exudative dermatis

Answer 45

-Skin lesions -Bacterial isolates

Question 46

Treatment of greasy pigs

Answer 46

-Antibiotics in early stages -Ceftiofur, enrofloxacin, lincomycin, sulfa/triprim -Later infections do not respond -Spray with disinfectants to kill them on skin

Question 47

Pyoderma in dogs

Answer 47

S. pseudintermedius -Dermatitis and folliculitis rarely systemic -Lesions start papular and progress to postules and intradermal abscesses (furuncles)

Question 48

treatment of pyoderma

Answer 48

Beta lactams

Question 49

MRSA

Answer 49

Resistant to B-lactams. Not more virulent just harder to treat. Comes from mecA