Staphylococcus Flashcards

1
Q

what are the general characteristics of all staphylococcus?

A

gram-positive cocci
catalase positive

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2
Q

where are commensal staphylococcus found?

A

skin and mucous membrane

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3
Q

How do opportunistic staphylococcus cause infection?

A

pyogenic infection by damage to skin or MM, immunocompromised patients

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4
Q

what are tests that can be used to differentiate between staphylococcus species?

A

coagulase
colony color
hemolysis

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5
Q

what is a positive and negative result of coagulase test indicative of with staphylococcus?

A

positive - pathogenic strains
negative - non-pathogenic strains

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6
Q

What is a staphylococcus species that causes hemolysis indicate?

A

causes disease

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7
Q

what are virulence factors present with staphylococcus?

A

adhesins
protein A
toxins
invasins
urease ( S. pesudintermedius)

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8
Q

what are adhesins?

A

facilitate bacterial attachment to host tissues

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9
Q

what is protein A?

A

virulence factor that interferes with opsonization and phagocytosis

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10
Q

what does alpha-toxin (alpha-hemolysin) do?

A

complete lysis of RBCs
spasm of smooth muscle

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11
Q

what does beta-toxin (beta-hemolysin) do?

A

incomplete/partial lysis of RBC

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12
Q

what does gamma-toxin (leucocidin) do?

A

cytolytic destruction of leukocytes

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13
Q

what enterotoxins do staph produce? what does it lead to?

A

enterotoxin A-E and G-J, SEA-SEJ, superantigen
food poisoning

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14
Q

which bacteria secrete toxins and which release?

A

secrete - exotoxins
release - endotoxins

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15
Q

what is a superantigen?

A

binds non-specifically to MHC-II and T cell receptor, leads to massive T cell activation

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16
Q

what is TSST-I?

A

toxic shock syndrom toxin - I
toxic shock when released into blood
superantigen

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17
Q

what is an exofoliative toxin?

A

proteases that exfoliate onto skin

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18
Q

what staphylococcus cases exudative epidermitis in pigs? what does this?

A

S. hyicus
exfoliative toxins

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19
Q

what are invasins?

A

enzymes that contribute to tissue destruction

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20
Q

what are some invasins that staph produce? what do they do

A

staphylokinase - break down blood clot
hyuluronidase - depolymerizes hyaluronic acid (CT)
capsule - protects bacterial cells from phagocytosis

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21
Q

what does S. pseudointermedius urease do?

A

raise pH of urine
possible formation urinary stones - urolithiasis

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22
Q

what is the causative agent of mastitis in cattle?

A

staphylococcus aureus

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23
Q

where is the main source of infection with mastitis?

A

udder

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24
Q

what virulence factors contribute to mastitis?

A

adhesins, invasins, capsule, leukocidin, hemolysins, exotoxins

toxins cause tissue damae

25
What are the two clinical manifestations of mastitis?
acute and peracute chronic/subclinical
26
How does acute and peracute mastitis present?
acute swelling of udder, peracute gangrenous (venous thrombosis > tissue necrosis), quarter sore and swollen, fever anorexia, lameness
27
what is the most common mastitis in cattle?
chronic/subclinical
28
How does chronic mastitis present in cattle?
elevated somatic cell counts, duct blockage and atrophy, limited antibiotic access (hard to treat), damage to udder and drop in milk yield, majority of cases become low grade or subclinical
29
How do you monitor/test for mastitis in cattle?
CMT - california mastitis test
30
what does CMT measure?
somatic cells in milk
31
How do you orient yourself when doing a CMT?
stand on right side of cow
32
what is a positive culture for mastitis?
>400,000 cells/mL
33
How can mastitis be prevented?
milking equipment - maintenance hygienic procedures eliminate fly-breeding sites culling (extended time, additional health problems)
34
what is the vaccine on the market that can prevent mastitis?
Lysigin
35
what is the causative agent of exudative epidermitis in pigs?
Staphylococcus hyicus
36
what age of pigs is exudative epidermitis seen mostly in?
3 months of age
37
what is the contagion level of exudative epidermitis?
highly contagious
38
what is the pathogenesis of exudative epidermitis?
enter skin through minor abrasions or bite wound same virulence factors as S. aureus except non-hemolytic exfoliative toxins
39
what are the clinical manifestations of exudative epidermitis in pigs?
excessive sebaceous secretion exfoliation and exudation on skin greasy exudate - 'greasy pig disease'
40
which age of pigs has a lower mortality?
adult
41
How do you diagnose exudative epidermitis in pigs?
clinical presentation culture and antibiotic sensitivity
42
How do you treat exudative epidermitis in pigs?
early systemic antibiotics - amoxicillin, fluroquinolone, ceftiofur, lincomycin
43
How do you control exudative epidermitis from spreading to other pigs?
strict isolation of affected pigs
44
what is the causative agent of pyoderma in cats and dogs?
S. pseudintermedius
45
what are the two types of pyoderma?
superficial - epidermis and hair follicles deep dermis - furunculosis (boils)
46
what are the virulence factors of S. pseudintermedium?
same as S. aureus adhesins most important
47
How does pyoderma present in dogs?
multifocal areas - alopecia, folllicular papules/pustules, crusts
48
what is the causative agent of this dog disease?
S. pseuintermedius
49
what is the causative agent of this pig disease?
S. hyicus
50
what is the causative agent of this cow disease?
S. aureus
51
How does pyoderma present in cats?
alopecia, ulceration, hemorrhagic crust, draining tracts
52
what is the causative agent of this cat disease?
S. pseudintermedius
53
what is MRSA?
methicillin-resistant S. aureus
54
what is MRSP?
methicillin-resistant S. pseudintermedium
55
How do you treat pyoderma?
antibiotics, medicated shampoos
56
How do you diagnose a staph infection?
isolation/culture - standard microscopy - gram + staphlycoccus
57
what agar is selecting for gram negative species?
MacConkey
58
What agar selects for Staphylococcus species?
mannitol salt agar
59
What should you do for owners who have pets carrying MRSA?
tell them to wash their hand thoroughly no broken skin around pet