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Microbiology > Lecture 11: Staphylococcus > Flashcards

Lecture 11: Staphylococcus Flashcards

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Biology 101 flashcards
1
Q

Is staphylococcus gram positive or negative

A

Positive

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2
Q

What test differentiates staphylococcus from streptococcus and what would the results be

A

Staphylococcus is catalase positive and streptococcus is catalase negative

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3
Q

what this

A

Staphylococcus

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4
Q

what test is this and which is strep vs staph

A

Catalase test
Left: streptococcus (-)
Right: staphylococcus (+)

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5
Q

Are staphylococcus commensal bacteria

A

Yes, but can become opportunistic pathogens when there is damage to skin or mucous membranes or in immunocompromised patients

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6
Q

What test differentiates against staphylococcus species

A

Coagulase test

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7
Q

What are the results of coagulase test for pathogenic vs non-pathogenic strains

A

Pathogenic strains positive, non-pathogenic strains negative

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8
Q

What test is this and what does it tell you about staphylococcus spp

A

coagulase test
Left: positive- pathogenic strains of staphylococcus
Right: negative- non-pathogenic strains

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9
Q

what test is this and what does it tell you about staphylococcus spp

A

Coagulase test
Left: negative- nonpathogenic strains of staphylococcus
Right: positive- pathogenic strains of staphylococcus

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10
Q

Which species of staphylococcus is the only one that does do hemolysis

A

S. Hyicus

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11
Q

What are adhesins

A

Cell wall proteins that bind fibrinogen and collage to facilitate bacterial attachment to host tissues

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12
Q

What does protein A do

A

Surface protein that binds IgG by Fc and interferes with opsonization and phagocytosis

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13
Q

What do alpha-toxins/ alpha-hemolysis do

A

Complete lysis of RBC’s, causes spasm of smooth muscle

Necrotizing and potentially lethal

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14
Q

What is the major toxin in gangrenous mastitis

A

Alpha toxin/alpha-hemolysin

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15
Q

What do beta-toxins/ beta hemolysin do

A

Incomplete/ partial lysis of RBC’s, damages cell membrane

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16
Q

What do gamma-toxins/ leucocidin do

A

Cytolytic destruction of leukocytes

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17
Q

What enterotoxins/ exotoxins are present in staphylococcus

A

Staphylococcus enterotoxin A-E and G-J; SEA-SEJ

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18
Q

What is SEA-SEJ responsible for

A

Diarrhea and vomiting when ingested (food poisoning)

Super antigen binds MHC2 to T-cell receptor leading to massive T cell activation

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19
Q

What superantigen is responsible for toxin shock syndrome when released into blood

A

Toxic shock syndrome toxin-1

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20
Q

What are exfoliative toxins

A

Proteases that contribute to skin lesions

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21
Q

What toxin is main virulence factor in S. Hyicus

A

Exfoliative toxins

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22
Q

What does staphylokinase do

A

Breaks down blood clots

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23
Q

What does hyluronidase do

A

Depolymerizes hyaluronic acid (CT) breaks open epithelial cells

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24
Q

What does coagulase do

A

Converts fibrinogen to fibrin —> produces blood clots

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25
Q

What is the purpose of a capsule

A

Protect bacterial cells from phagocytosis

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26
Q

Which staph/ virulence factor raises pH in urine, forms urinary stones

A

S. Pseudointermedius urease

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27
Q

What is the staph causative agent in contagious mastitis

A

S. Aureus

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28
Q

What is the main source of infection in S. Aureus contagious mastitis

A

Colonize the teat skin, teat canal and udder

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29
Q

What is the pathogens is of contagious mastitis in cattle

A
  1. Adhesins facilitate bacterial attachment
  2. Invasins facilitate tissue invasion
  3. Capsule protect bacteria from phagocytosis by host cell
  4. Leukocidin, hemolysins, exotoxins cause tissue damage
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30
Q

What stage of lactation does acute and peracute contagious mastitis occur

A

Early lactation

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31
Q

What are the clinical manifestations of acute and peracute contagious mastitis

A

Acute swelling of udder, purulent secretion

32
Q

What does peracute gangrenous cause in contagious mastitis

A

Venous thrombosis and congestion of the udder that lead to tissue necrosis

33
Q

What are the signs of peracute gangrenous contagious mastitis

A

Quarter is sore and swollen, fever, anorexia, lameness, toxemia may cause death

34
Q

What is the most common form of contagious mastitis in cattle

A

Chronic/subclinical

35
Q

What is elevated in chronic/subclinical mastitis

A

Somatic cell counts

36
Q

The inflammatory response in chronic/ subclinical mastitis results in what

A

Duct blockage and atrophy of associated alveoli

37
Q

Influx of phagocytic cells lead to ___ and limits __ in chronic/subclinical contagious mastitis

A

Abscess formation and fibrosis, limits antibiotic access (hard to tx)

38
Q

In chronic/subclinical mastitis there is gradual damage to ___ and drop in ___

A

Udder, milk yield

39
Q

How do you monitor contagious mastitis in cattle

A

CMT- measures somatic cells in milk

40
Q

What cell is high in mastitis

A

Leukocytes

41
Q

How does a CMT test work

A

Reagent reacts with leukocytes and will form gel with infection, the greater the gel the worse the infection

42
Q

How do you diagnose contagious mastitis in cattle

A

Culture results
If culture is positive test individual causes of high SCC (>400k)

43
Q

What is the treatment for contagious mastitis in cattle

A

Intramammary (preferred), IM or IV antibiotics

44
Q

How do you prevent contagious mastitis

A
  1. Milking equipment maintenance
  2. Hygienic procedures
  3. Milking order: healthy, first lactating, older cows first then subclinical mastitis last or separate
    4.eliminate fly breeding sites
  4. Culling- cows with persistent S. Aureus infection
45
Q

What vaccine is available to prevent contagious mastitis (staph aureus)

A

Lysigin

46
Q

The vaccine for contagious mastitis (s. Aureus) is only effective in who

A

Healthy young heifers

47
Q

Does the staph. Aureus contagious mastitis vaccine prevent infection

A

No lowers effect and milder diasease

48
Q

What is the causative agent in exudative epidermitis in pigs

A

Staphylococcus Hyicus

49
Q

What pigs are commonly affected by S. Hyicus

A

Up to 3 months old

50
Q

What is the pathogens is for exudative epidermitis in pigs

A
  1. Enter the skin through minor abrasions or bite wounds
  2. Adhesins, invasins, leukocidins, capsules, exotoxins (no hemoylsins)
  3. Exfoliative toxins are main cause
51
Q

What is the clinical manifestation of exudative epidermitis in pigs

A

Excessive sebaceous secretions, exfoliation and exudation on skin, erosions of snout, foot pads, anorexia, depression, fever

52
Q

Exudative epidermitis in pigs is also called ___ disease

A

Greasy pig disease

53
Q

What pigs are affected in the acute form of exudative epidermitis

A

Suckling piglets- usually die within 48hrs

54
Q

What pigs are affected in chronic form of exudative epidermitis in pigs

A

Weaned pigs

55
Q

What is the morbidity and morality associated with exudative epidermitis in pigs

A

Morbidity: 20-100%
Mortality: ~90% (low morality in adult pigs)

56
Q

How do you diagnose exudative epidermitis in pigs

A
  1. Clinical presentation- skin lesions
  2. Culture and antibiotic sensitivity
57
Q

Pig presents with skin lesions, histo shows a gram positive organism. It is also coagulase positive and non-hemolytic. What is likely cause

A

S. Hyicus

58
Q

What is treatment for exudative epidermitis in pigs

A
  1. Early systemic antibiotic (7-10days)
  2. Daily topical antiseptic
  3. Drugs: amoxicillin, fluoroquinolones, ceftiofur, linomycin
59
Q

How can you control exudative epidermitis in pigs

A
  1. Strict isolation of affected pigs
  2. Cleaning and disinfection
  3. Wash sows with antiseptic before farrowing
60
Q

Is there a vaccine for exudative epidermitis in pigs

A

Yes, but only shows some success in chronically infected herds

61
Q

What is the causative agent staph pyoderma in cats and dogs

A

S. Pseudointermedius

62
Q

Where does the superficial infection of S. Pseudointermedius infect

A

Epidermis and hair follicles

63
Q

Where does a deep dermis infection of S. Pseudointermedius result in

A

Furunculosis (boils)

64
Q

What is the pathogens is for S. Pseudointermedius causing pyoderma

A
  1. Adhesins facilitate bacterial attachment
  2. Invasins
  3. Capsules prevent phagocytosis
  4. Leukocidins, hemolysins, exotoxins
65
Q

What is the most important virulence factor for S. Pseudointermedius pyoderma

A

Adhesins most important for bacterial stickiness to keratinocytes

66
Q

What are the clinical manifestations of S. Pseudointermedius pyoderma in dogs

A

Multifocal areas of alopecia, follicular -apples, pustules, crusts

67
Q

What are the clinical manifestations of S. Pseudointermedius pyoderma in cats

A

Alopecia, ulcerations, hemorrhagic crusts, draining tracts

68
Q

How do you diagnose S. Pseudointermedius pyoderma in cats and dogs

A
  1. Clinical signs- hair loss, papules, pustules
  2. Bacterial culture and susceptibility testing
69
Q

Why is it important to test for sensitivity in S. Pseudointermedius pyoderma

A

To determine if methicillin resistant staphylococcus Pseudointermedius (MRSP)

70
Q

What is the treatment of pyoderma in cats and dogs

A
  1. Narrow spectrum antibiotic for 30 days
  2. Resolution for 7 days
  3. Topical- mupirocin
  4. Medicated shampoos
71
Q

What medicated shampoo is showing promising results for dogs with Staph pyoderma

A

Sodium hypochlorite and salicylic acid shampoo

72
Q

What is the gold standard for diagnosing staphylococcus infections

A

Culture

73
Q

What do you expect to see on microscopy with staph infections

A

Neutrophils containing gram positive staphylococcus

74
Q

What isolation medias can be used to dx staph

A
  1. Blood agar
  2. MacConkey- gram - so nothing happens
  3. Mannitol salt agar- NaCl selects for staphylococcus
  4. Purple agar- golden color with S. Aureus
75
Q

What agar can be used to identify S. Aureus from other staphs

A

Purple agar

Microbiology (31 decks)

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