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Year 2 > Intro to microbiology > Flashcards

Intro to microbiology Flashcards

1
Q

Role of capsule

A

Provides protection

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2
Q

Difference between gram-positive and gram-negative bacteria

A

Gram positive: thick peptidoglycan layer in cell wall

Gram-negative: think peptidoglycan layer and an additional outer layer containing lipopolysaccharides (endotoxins)

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3
Q

Role of fimbriae

A

Allow bacteria to adhere to cell surfaces and exchange plasmids

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4
Q

Name the four bacterial shapes

A
  1. Cocci
  2. Bacilli
  3. Vibrio
  4. Spirochaete (spiral rods)
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5
Q

What colour does gram positive staining show

A

purple (Postive = Purple)

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6
Q

What colour does gram negative staining show

A

Red

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7
Q

Technique for gram staning

A
  1. Heat fix sample to slide
  2. Add methyl violet
  3. Add iodine, will fix methyl violet to gram-positive samples
  4. Add alcohol to decolourise gram-negative samples
  5. Counterstain with basic fuchsin (red)
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8
Q

When is Ziehl-Neelsen staining done

A

For mycobacteria app

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9
Q

Why can gram staining not be used for mycobacteria

A

Because the cell wall contained mycolic acids

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10
Q

What do mycobacteria app staining Ziehl-Neelsen staning

A

Pink/red dye retained as they are acid fast

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11
Q

What do non-mycobacteria staining Ziehl-Neelsen staning

A

BLUE

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12
Q

Role of the catalase test

A

Differentiates between staphylococci (positive) and streptococci/enterococci (negative)

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13
Q

What is catalase

A

Break down hydrogen peroxide to H2o and O2

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14
Q

What is the reaction seen when catalase is added to staphylococci

A

H2O2 + staphylococci -> gas bubbles

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15
Q

What is seen when catalase is added to streptococci and Enterococci

A

NOTHING

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16
Q

What is coagulase

A

Enzyme that causes fibrin to clot - prevents phagocytosis:

Bacterial sample + plasma -> clot (staphylococcus aureus)

Bacterial sample + plasma -> no clot (not staphylococcus)

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17
Q

What does the oxidase help distinguish

A

Those that produce CYTOCHROME OXIDASE

Pseudomonas vs Neiserria

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18
Q

Reactions seen in oxidase test

A

Bacterial sample + Methylphenylenediamine -> Blackish/purple colour (oxidase positive)

Bacterial sample + Methylphenylenediamine -> No colour change (Oxidase negative)

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19
Q

Role of optochin test

A

Differentiates between streptococci pneumonia from other strep

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20
Q

Reaction seen in positive optochin test

A

Strep pneumonia + optochin -> LYSIS

Other alpha haemolytic strep will not undergo lysis

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21
Q

What is the role of Metronidazole in blood cultures

A

Inhibits growth of ANAEROBES

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22
Q

What is the MacConkey agar made of

A

Bile salts: Only permit growth of enteric bacteria
Lactose: Fermentation of lactose produces acidic environment (pink colour)
pH indicator

ISOLATES and identifies enteric bacteria

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23
Q

Results of MacConkey agar

A

Red-pink colony; Escherichia coli and Klebsiella app

Clear colony; Salmonella app, Shigella app and pseudomonas app

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24
Q

Role of blood agar

A

Differentiates between alpha haemolytic and beta haemolytic colonies of streptococci

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25
Q

What do blood agars compose of

A

Mammalian blood

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26
Q

Realist of alpha haemolytic (viridian’s) in blood agar

A

Green pigment from partial Hb breakdown

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27
Q

Results of beta haemolytic in blood agar

A

CLEAR ZONE as it causes complete Hb breakdown

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28
Q

What is Lancefield grouping

A

Differentiates between S. Progenies (A), S. agalactiae (B) and Enterococcus

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29
Q

What do Lancefield grouping detect

A

Surface antigens

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30
Q

What bacteria produce exotoxins

A

Gram-positive bacteria (these have specific antigens)

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31
Q

What are endotoxins

A

Component of cell wall released when bacteria is damaged

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32
Q

What endotoxin is released by gram-positive

A

Lipoteichoic acid

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33
Q

What endotoxin is released by gram-negative bacteria

A

Lipopolysaccharides

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34
Q

What effect do endotoxins have

A

Septic shock

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35
Q

Ship of Streptococcus

A

Chains or diplococci

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36
Q

Gram-staining result of strep

A

Positive

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37
Q

Catalase test for strep

38
Q

Optochin test for strep

A

Positive: Strep. pneumonia)

39
Q

Blood agar for strep

A 
Alpha:
Oralis
Sanguis
Mutans
Mitis
Beta:
Pyogenes
Agalactiae
Non:
Enterococcus faecalis
40
Q

Shape of staphylococcus

A

Cocci in clumps

41
Q

Gram staining of staphylococcus

42
Q

Catalase test for staph

43
Q

COAGULASE test for staphylococcus

A

Positive: Aureus
Negative: Other species

44
Q

Colour of staph colonies

A

Except aureus (gold) they are all WHITE

45
Q

Are staphylococcus and streptococcus aerobic or anaerobic

46
Q

What shape are corynebacterium

47
Q

Gram staining of corny bacterium

48
Q

Oxygen requirement of corynebacterium

49
Q

Shape of listeria

50
Q

Staining of listeria

51
Q

What shape is Colostridium

52
Q

Staining of clostridium

53
Q

Oxygen requirement for clostridium

54
Q

Shape of neisseria

A

Diplococci

55
Q

Staining of neisseria

A

GRAM NEGATIVE

56
Q

What test is done for neisseria

A

Oxidase: Positive

57
Q

Oxygen requirement of neisseria

58
Q

What shape and gram stain are enterobacteriacae

A

Bacilli gram negative

59
Q

What culture do we do for enterobacteriacae

A
  1. MAcCOnkey Agar: Red/pink for E.coli
60
Q

Shape of helicobacter

A

Curved bacilli

61
Q

Gram-stain of helicobacter

62
Q

Oxygen requirement for helicobacter

63
Q

Shape and stain of pseudomonas

A

Bacilli and Gram-negative

64
Q

What test is done for pseudomonas app

A

Oxidase positive

65
Q

Do Staph aureus form spores

66
Q

DO Staph aureus nove

A

Non-motile

67
Q

How do bacteria divide

A

Binary fission

68
Q

What enzyme mediates binary fission in bacteria

69
Q

How does S.aureus spread

A 
Contact with pus from infected wound
Skin-to-skin contact with an infected person 
Contact used by an infected person 
Joint replacements 
IV drug users
Diabetics
70
Q

What enzymes are secreted by staph aureus

A
  1. Coagulase - clots plasma and coats bacterial cell to prevent phagocytosis
  2. Hyaluronidase to break down hyaluronic acid and spread
  3. Deoxyribonuclease
71
Q

What enzyme allows staphylococcus to become resistant to antibiotics

A

Penicillinase which breaks down beta-lactam ring of penicillin rendering it ineffective

72
Q

What diseases are caused by pseudomonas aerguinosa by system

A
  1. Lungs - pneumonia
  2. Septic shock - CV
  3. UTI
  4. Haemorrhage and necrosis of skin - derma
  5. Osteomyelitis - MSK
73
Q

Characteristics of strep viridian’s

A
  1. Gram-Positive
  2. Alpha-haemolytic
  3. Optochin resistant
74
Q

Where is Staphylococcus Aureus commonly found

A

Skin

Upper Resp Tract

75
Q

What diseases can Staphylococcus Aureus cause

A 
SKIN: Abscesses in what + sebaceous glands
Folliculitis
Ear Infection 
Impetigo 
Cellulitis

MSK: OSTEOMYELITIS
SEPTIC ARTHRITIS

CV: ENDOCARDITIS

BLOOD: SEPTICAEMIA

LUNGS: ASTHMA
SINUSITIS

GI: GASTROENTERITIS

76
Q

What life-threatening condition can be caused by Staphylococcus Aureus

A

TOXIC SHOCK SYNDROME

77
Q

What causes Toxic Shock Syndrome

A

S. Pyogenes

S. Aureus

78
Q

Clinical presentation of toxic shock syndrome

A 
Fever
Sweats
Rash
Low BP 
Organ Failure
79
Q

Where is Streptococcus Pyogenes found

80
Q

What bacteria can also be lance field A antigens

A

S. DYSGALACTIAE

S. ANGINOSUS

81
Q

What haemolytic group is Strep Pyogenes

A

Beta Haemolytic

82
Q

Enzymes produced by Strep Pyogenes

A
  1. STREPTOKINASE
  2. HYALURONIDASE
  3. C5a peptidase (stops influx of neutrophils)
83
Q

What does Streptokinase do

A

Activates plasminogen + digests proteins

84
Q

What does Hyaluronidase do

A

Breaks down hyaluronic acid in connective tissue

85
Q

Diseases caused by Strep. Pyogenes

A

SKIN: PHARYNGITIS
CELLULITIS

KIDNEY: GLOMERULONEPHRITIS

86
Q

What factor favour pseudomonas aerguinosa

A

Low Temperatures

87
Q

What diseases are caused by PSEUDOMONAS AERGUINOSA

A

Lungs: PNEUMONIA

GU: UTI

SKIN: NECROSIS

MSK: OSTEOMYELITIS of feet

88
Q

What bacteria commonly cause Acute Glomerulonephritis

A
  1. Strep. pyogenes after pharyngitis or cellulitis in a child
89
Q

Characteristics of strep. pyogenes

A
  1. Beta haemolytic, Lancefield group A strep
90
Q

What viruses can cause acute glomerulonephritis

A

Hep B and C

91
Q

What worm can cause acute glomerulonephritis

A

Schistomiasis

Year 2 (155 decks)

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