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UCLMS Yr 1 Mod 2: Infection and Defence > Bacteria > Flashcards

Bacteria Flashcards

1
Q

What is the structure of a Bacteria (12)

A 
Flagellum
Basal Body
DNA coiled into nucleoid
Cell Wall
Capsule
Infolding of plasma membrane
Cytoplasmic inclusion
Pili
Plasma Membrane
Cytoplasm
Plasmid
70s Ribosomes
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2
Q

What are the 3 ways of classifying bacteria

A

Gram Stain
Shape
Taxonomy

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3
Q

What are the 4 phases of bacterial division by binary fission

A

Lag Phase
Logarithmic Phase
Stationary Phase
Death Phase

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4
Q

What are 7 ecological factors influencing flora

A 
Humidity
pH
Attachment/retention
oxygen tension
Host inhibitors
microbial inhibitors
nutrients
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5
Q

How is the gram stain performed

A

Crytal Violet Applied
Iodine Applied (fixation)
Methanol (Decolorisation)
Safranin (Counter Stain)

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6
Q

What colour do bacteria turn after the addition of crystal violet

A

Purple

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7
Q

What colour do bacteria turn after the addition of iodine in the gram stain

A

Remain Purple

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8
Q

What colour do Gram-Negative bacteria turn after the addition of alcohol

A

Colourless

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9
Q

What colour do gram-positive bacteria turn after the addition of alcohol

A

Remain purple

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10
Q

What colour do Gram positive bacteria become after the addition of the counter stain safranin

A

remain purple

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11
Q

What colour do gram-negative bacteria become after the addition of the counter stain safranin

A

Red

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12
Q

What are the three shapes of bacteria

A

Coccus/Cocci
Bacillus/Bacilli/Rods
Spirochetes

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13
Q

What are the three shapes of bacteria

A

Coccus/Cocci
Bacillus/Bacilli/Rods
Spirochetes

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14
Q

What is the name of a bacteria which requires oxygen

A

Obligate Microbe

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15
Q

What is the name of a bacteria which require reduced oxygen

A

Microaerophile

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16
Q

What is the name of the bacteria which require total absence of oxygen

A

Obligate Anaerobe

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17
Q

What is the name of a bacteria which are tolerant of oxygen level

A

facultative anaerobe

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18
Q

What is the name of the bacteria which require increased CO2

A

Capnophile

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19
Q

What are 2 examples of Gram-positive Cocci

A

Streptococci

Staphylococci

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20
Q

What is an example of Gram-Positive Rod

A

Listeria

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21
Q

What is an example of Gram-negative cocci

A

Neisseria

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22
Q

What is an example of Gram-negative rods

A

Enterobacteria (e.g. Escherichia)

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23
Q

what is a description of the Cell Wall of the Gram-Positive Bacteria

A

Thick murein layer protects against desiccation but is susceptible to penicillins

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24
Q

What is the difference between Staphylococcus and Streptococcus

A

Staph found in clusters

Strep found in chains/pairs

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25
Q

What is an example of a coagulase-positive Staph

A

Staph. Aureus

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26
Q

What are 3 examples of Coagulase-negative Staph

A

Epidermis
Haemolyticus
Capitis

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27
Q

What is the difference between Coagulase positive and negative bacteria

A

Coagulase Positive has a grainy look, with darker blue patches sprinkled on a light blue background
Coagulase Negative have a smooth look with a gradient of blue, darker towards the middle

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28
Q

What are 3 subclasses of Step. Bacteria

A

Alpha, Beta and Gamma Haemolytic

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29
Q

What does Beta Haemolysis look like

A

Large haemolytic activity with obvious signs of haemolysis

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30
Q

What does Alpha Haemolysis look like

A

Less obvious than Beta Haemolysis, but still with pronounced haemolysis

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31
Q

What does Gamma haemolysis look like

A

Very little haemolytic activity, but still present nonetheless

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32
Q

What Bacteria are Beta Haemolytic (1)

A

Group A Strep.

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33
Q

What bacteria are Alpha Haemolytic (1)

A

Strep. viridanse

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34
Q

What bacteria are gamma haemolytic (1)

A

Endocroccus

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35
Q

Which Gram-positive bacteria are sporing (2)

A

Bacillus

Clostridium

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36
Q

Which Gram-Positive rods are non-sporing

A

Listeria

Propronibacterium

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37
Q

What is a description of the cell wall of gram-negative bacteria

A

The Cell wall is more complex with an inner and outer membrane separated by periplasm and thin later of murein

38
Q

Which part of the Gram-Negative bacteria releases antibiotics

A

Porins

39
Q

What are three subclasses of Gram-Negative Bacteria

A

Rods
Curved Rods
Diplococci

40
Q

Why is the gram stain unhelpful when identifying mycobacterium

A

thick lipid-rich cell wall

41
Q

What technique can be used to identify mycobacterium

A

Using a fluorochrome stain, and viewing under a microscope with ultraviolet light

42
Q

Which stain can be used on a mycobacterium

A

Ziehl-Neelsen Stain

43
Q

How is the Ziehl-Neelsen stain performed

A

Heat to allow stain to penetrate cell wall
Decolourising with acid and then counterstaining
Acid Fast Bacilli (AFBs) are visible

44
Q

What are the smallest organisms capable of growth on a cell-free medium

A

Mycoplasmas

45
Q

What do Mycoplasmas lack

A

A rigid cell wall

46
Q

Which bacterium is in the commensal flora of the Nose (nares)

A

Staph. Aureus

47
Q

Which bacterium is in the commensal flora of the Skin

A

Staph. Epidermidis

48
Q

Which bacterium is in the commensal flora of the Upper Respiratory tract

A

Strep. Pneumoniae

49
Q

Which bacterium is in the commensal flora of the Gut

A

Escherichia Coli

50
Q

Which bacterium is in the commensal flora of the gut and vagina

A

Anaerobes

51
Q

How do commensal bacteria cause disease

A

Move from the commensal area into a different location

52
Q

Which bacteria are never commensal and what do they cause (4)

A

Strep. Pyogenes - Group A Strep
Neisseria Gonorrhoea - Gonorrhoea
Bordetella Pertussis - Whooping Cough
Mycobacterium Tuberculosis - TB

53
Q

Which bacteria is a typical opportunistic pathogen (causes disease in hospitalised/compromised)

A

Pseudomonas Aeruginosa

54
Q

What is a Primary Pathogen

A

Inherent Ability to breach host defences

55
Q

What is an opportunistic Pathogen

A

Require underlying defect or altercation in host defences

56
Q

What is a polymicrobial infection

A

Multiple pathogens working together facilitating each others survival

57
Q

What are 3 ways microorganisms can gain access to the body

A

Motility - Flaggeli
Chemotaxis - Chemicals that guide bacteria by electrostatic and vdw forces
Adhesions

58
Q

How do bacteria evade the body’s defences (4)

A

Protein A - binds to the constant region of the antibody (IgG), nullifying the effect
Toxic Shock Syndrom Toxins
Coagulase - Produce Clots
Biofilm formation - Bacteria join together, with outer layer highly resistant to antibiotics, protecting bacteria

59
Q

What type of bacteria produces endotoxins

A

Gram-Negative Bacteria

60
Q

What is endotoxin

A

Lipid A moiety in the lipopolysaccharide of Gram-Negative organisms

61
Q

Which cytokines does Lipid A stimulate

A

IL1 and TNF

62
Q

What does a Cytokine Storm Result in

A

Multiple Organ Failure

63
Q

What are 2 types of exotoxins and what do they target

A

Shiga Toxin - Destroys ribosomes

Diphtheria Toxin - Cause damage to pharynx, myocardium and axons

64
Q

What does Phage encoded mean

A

encoded by a virus in a bacteria

65
Q

What do enterotoxins cause

A

Overactivity of secretory mechanisms

66
Q

What do neurotoxins do

A

interferons with neurotransmitter activity

67
Q

How do superantigens work

A

Bind on the outside of the MHC-TCR complex, causing huge cytokine storm

68
Q

What is an example of a superantigen (1)

A

Strep. Pyogenic exotoxin

69
Q

What is the chemical structure of endotoxin

A

Lipopolysaccharide

70
Q

What is the pathogenesis of rheumatic fever

A

Immunopathology

71
Q

What is an antibiotic

A

A substance produced by microorganisms that in small amounts inhibits the growth of another microbe

72
Q

What are the Antimicrobial mechanisms of action (5)

A 
Inhibition of Cell Wall Synthesis
Inhibition of protein synthesis 
Injury to the plasma membrane
Inhibition of DNA/RNA synthesis
Inhibition of essential metabolites
73
Q

How do Beta-Lactams work

A

Inhibit enzymes involved in cell wall assembly

74
Q

What are the three groups of beta lactams

A

Penicillins
Cephalosporins
Carbapenems

75
Q

What are 2 types of glycopeptides

A

Transglycosylase

Transpeptidase

76
Q

How do macrolides work

A

Prevent fMet and Arg from coming together

77
Q

How do Quinolones work

A

Prevent bacterial DNA from supercoiling

78
Q

Which is the Enzyme which supercoild Bacterial DNA

A

DNA gyrase

79
Q

What are the 3 influences on drug efficacy

A

Distribution
Metabolism
Excretion

80
Q

What are the 5 safety concerns with the use of antimicrobials

A 
Toxicity
Interactions with other medications
Hypersensitivity
Foetal Damage/risk to pregnant women
Antibiotic Resistance
81
Q

How do genetic resistances come about in bacteria (3)

A

Acquisition of DNA
Alteration of DNA
Loss of DNA

82
Q

What are resistant mechanisms in bacteria (4)

A

Altered Target site
bypass pathways
decreased uptake through reduced penetration or increased efflux
Enzymatic inactivation or modification

83
Q

Why is it disadvantageous in the absence of antibiotic pressure for resistant bacteria (4)

A

additional proteins
loss of transport pathways
additional energy expenditure
less efficient enzymes/pathways

84
Q

What si the site of action for beta-lactams

A

Cell Wall - transglycosylases and transpeptidases involved in peptidoglycan biosynthesis

85
Q

What is the action of beta-lactamases

A

Beta-lactamases hydrolyse Beta-lactam antibiotics, rendering them inactive

86
Q

What are the main sites of gentamicin (2)

A

Nephrotoxicity

Ototoxicity

87
Q

What are the main reservoirs for pathogens (5)

A 
Humans
Animals
Surfaces
Water
Air
88
Q

What is the name of pathogens which have an animal reservoir

A

Zoonoses

89
Q

What are the main forms of transmission (8)

A 
Inhalation
Ingestion 
Inoculation
Contact 
Sexual
Transplacental
Vector Borne
Blood Transfusion and other iatrogenic modes
90
Q

Which mucosal surface is sterile in a healthy person

A

Bladder

91
Q

Which are common zoonosis (1)

A

Lyme disease

UCLMS Yr 1 Mod 2: Infection and Defence (7 decks)

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