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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
What do blood agars compose of
Mammalian blood
26
Realist of alpha haemolytic (viridian's) in blood agar
Green pigment from partial Hb breakdown
27
Results of beta haemolytic in blood agar
CLEAR ZONE as it causes complete Hb breakdown
28
What is Lancefield grouping
Differentiates between S. Progenies (A), S. agalactiae (B) and Enterococcus
29
What do Lancefield grouping detect
Surface antigens
30
What bacteria produce exotoxins
Gram-positive bacteria (these have specific antigens)
31
What are endotoxins
Component of cell wall released when bacteria is damaged
32
What endotoxin is released by gram-positive
Lipoteichoic acid
33
What endotoxin is released by gram-negative bacteria
Lipopolysaccharides
34
What effect do endotoxins have
Septic shock
35
Ship of Streptococcus
Chains or diplococci
36
Gram-staining result of strep
Positive
37
Catalase test for strep
NEGATIVE
38
Optochin test for strep
Positive: Strep. pneumonia)
39
Blood agar for strep
``` Alpha: Oralis Sanguis Mutans Mitis Beta: Pyogenes Agalactiae Non: Enterococcus faecalis ```
40
Shape of staphylococcus
Cocci in clumps
41
Gram staining of staphylococcus
Positive
42
Catalase test for staph
POSITIVE
43
COAGULASE test for staphylococcus
Positive: Aureus Negative: Other species
44
Colour of staph colonies
Except aureus (gold) they are all WHITE
45
Are staphylococcus and streptococcus aerobic or anaerobic
AEROBIC
46
What shape are corynebacterium
Bacilli
47
Gram staining of corny bacterium
POSITIVE
48
Oxygen requirement of corynebacterium
AEROBIC
49
Shape of listeria
Bacilli
50
Staining of listeria
Positive
51
What shape is Colostridium
Bacilli
52
Staining of clostridium
POSITIVE
53
Oxygen requirement for clostridium
ANAEROBIC
54
Shape of neisseria
Diplococci
55
Staining of neisseria
GRAM NEGATIVE
56
What test is done for neisseria
Oxidase: Positive
57
Oxygen requirement of neisseria
AEROBIC
58
What shape and gram stain are enterobacteriacae
Bacilli gram negative
59
What culture do we do for enterobacteriacae
1. MAcCOnkey Agar: Red/pink for E.coli
60
Shape of helicobacter
Curved bacilli
61
Gram-stain of helicobacter
NEGATIVE
62
Oxygen requirement for helicobacter
Aerobic
63
Shape and stain of pseudomonas
Bacilli and Gram-negative
64
What test is done for pseudomonas app
Oxidase positive
65
Do Staph aureus form spores
No
66
DO Staph aureus nove
Non-motile
67
How do bacteria divide
Binary fission
68
What enzyme mediates binary fission in bacteria
Autolysin
69
How does S.aureus spread
``` 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
What enzymes are secreted by staph aureus
1. Coagulase - clots plasma and coats bacterial cell to prevent phagocytosis 2. Hyaluronidase to break down hyaluronic acid and spread 3. Deoxyribonuclease
71
What enzyme allows staphylococcus to become resistant to antibiotics
Penicillinase which breaks down beta-lactam ring of penicillin rendering it ineffective
72
What diseases are caused by pseudomonas aerguinosa by system
1. Lungs - pneumonia 2. Septic shock - CV 3. UTI 4. Haemorrhage and necrosis of skin - derma 5. Osteomyelitis - MSK
73
Characteristics of strep viridian's
1. Gram-Positive 2. Alpha-haemolytic 3. Optochin resistant
74
Where is Staphylococcus Aureus commonly found
Skin | Upper Resp Tract
75
What diseases can Staphylococcus Aureus cause
``` 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
What life-threatening condition can be caused by Staphylococcus Aureus
TOXIC SHOCK SYNDROME
77
What causes Toxic Shock Syndrome
S. Pyogenes | S. Aureus
78
Clinical presentation of toxic shock syndrome
``` Fever Sweats Rash Low BP Organ Failure ```
79
Where is Streptococcus Pyogenes found
Skin
80
What bacteria can also be lance field A antigens
S. DYSGALACTIAE S. ANGINOSUS
81
What haemolytic group is Strep Pyogenes
Beta Haemolytic
82
Enzymes produced by Strep Pyogenes
1. STREPTOKINASE 2. HYALURONIDASE 3. C5a peptidase (stops influx of neutrophils)
83
What does Streptokinase do
Activates plasminogen + digests proteins
84
What does Hyaluronidase do
Breaks down hyaluronic acid in connective tissue
85
Diseases caused by Strep. Pyogenes
SKIN: PHARYNGITIS CELLULITIS KIDNEY: GLOMERULONEPHRITIS
86
What factor favour pseudomonas aerguinosa
Low Temperatures
87
What diseases are caused by PSEUDOMONAS AERGUINOSA
Lungs: PNEUMONIA GU: UTI SKIN: NECROSIS MSK: OSTEOMYELITIS of feet
88
What bacteria commonly cause Acute Glomerulonephritis
1. Strep. pyogenes after pharyngitis or cellulitis in a child
89
Characteristics of strep. pyogenes
1. Beta haemolytic, Lancefield group A strep
90
What viruses can cause acute glomerulonephritis
Hep B and C
91
What worm can cause acute glomerulonephritis
Schistomiasis

Year 2 (155 decks)

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