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Microbiology FPP > Bacteriology > Flashcards

Bacteriology Flashcards

1
Q

What are the capsulated bacteria

A

YES Some Nasty Killers Have Pretty Big Capsules

Yersinia pestis
Escherichia coli
Salmonella typhi
Streptococcus pneumoniae
Neisseria menigitidis
Klebsiella pneumoniae
Haemophilus influenzas
Pseudomonas aeruginosa
Bacillus anthracis and Bordetella pertussis
Crypococcus neoformans

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2
Q

Give 3 characteristics of the bacteria cell

A

Prokaryotic
Non membrane organelle
DNA is circular

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3
Q

What’s the cell wall of bacteria made of

A

Peptidoglycan

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4
Q

What is peptidoglycan

A

Repeating disaccharide with amino acid in a side chain extending from each disaccharide

This results in a stable cross linked structure

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5
Q

Function of the bacterial cell wall

A

•Maintains cell osmotic pressure in hypotonic environment
•contributes to sensitivity to certain antimicrobial agents (penicillin) and the immune system (antibodies, phagocytes)
•determines reactivity to Gram stain

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6
Q

What’s the size of a bacteria

A

0.2-5Mm

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7
Q

Describe the ribosomes of bacteria

A

70s (50s+30s)
The 2 subunits are targets for different antibiotics

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8
Q

What inhibits the formation of 50s ribosomal subunit in bacteria

A

Erythromycin

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9
Q

What drugs target the 50s ribosomal subunit of bacteria

A

Macrolides
Clindamycin
Chloramphenicol

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10
Q

What drugs target the 30s ribosomal subunit of bacteria

A

Aminoglycosides
Tetracycline

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11
Q

What is a protoplast

A

If peptidoglycan is digested away from the cell, gram positive cells lose their cell walls and become protoplasts.

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12
Q

Give 2 characteristics of the cell wall of a gram + bacteria

A

Thick peptidoglycan (60-90% of cell wall)
Contains Tachoic acid

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13
Q

What three things are present in gram- bacteria but absent in gram+ bacteria

A

Outer membrane
Periplasmic space
Lipopolysaccharide (endotoxin)

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14
Q

What’s the function of the techoic acid

A

( polysaccharide, antigenic) Important for serologic identification of some bacteria

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15
Q

Characteristics of the cell wall in a gram- bacteria

A

•Very thin peptidoglycan
•No techoic acid
•A unique outer cell membrane
•Periplasmic space
•Lipopolysacharide (endotoxin)

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16
Q

Function of the outer cell membrane in gram- bacteria

A

◦excludes all hydrophobic molecules (•This protects the bacteria from the action of bile salts and toxins of the gut)
◦contain narrow, restrictive protein channels called porins which permits passage of low molecular weight hydrophilic molecules.
◦Large antibiotic molecules penetrate the outer membrane slowly (antibiotic resistance)

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17
Q

Where is the periplasmic space found

A

between the cytoplasmic membrane and the outer membrane

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18
Q

What does the Periplasmic space contain in gram- bacteria

A

contains digestive enzymes and other transport proteins

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19
Q

What does the lipopolysaccharide in the gram- bacteria contain

A

•polysaccharide O antigens used in typing gram negatives (easiest target for the humoral response of the host)
• lipid A or endotoxin. Endotoxin can trigger fever and septic shock in gram negative infections

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20
Q

What does endotoxin trigger in gram- bacterial infections

A

fever and septic shock

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21
Q

What’s the function of Lipopolysaccharide found on the gram- bacteria

A

LPS also protects the cell from phagocytosis, penicillins and the antibacterial enzyme lysozyme

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22
Q

What are the flagella built of

A

Flagella are built of proteins and are strongly antigenic.

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23
Q

What’s the antigen found in flagella

A

The H antigens and are important targets of protective antibody response

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24
Q

What’s another name for o antigen

A

Somatic antigen

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25
Q

What are the differences shapes or forms
flagella can be

A

•polar/monotrichous (single cell, restricted to the pole),
• lophotrichous (a tuft at one pole)
•amphitrichous: one or more flagella at both ends of the cell
•peritrichous (distributed over the cell surface).
•ceohalotrichous: a tuft both ends

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26
Q

How do you describe a bacteria with no flagella

A

Atrichous

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27
Q

Other than locomotion, what other function does the flagella have in bacteria

A

• Flagella can help in identifying certain types of bacteria e.g, Proteus species show a rapid ‘swarming’ type of growth on solid media.
•Highly antigenic

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28
Q

Describe the capsule of a bacteria

A

A gelatinous polysaccharide and/or polypeptide outer covering
•It may be firmly attached or loosely attached as a slime layer

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29
Q

What’s is a biofilm

A

Within the slime layer (more slimy than capsule) many cells can come together to form a biofilm, which may protect them from antibiotics and toxins

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30
Q

Functions of a capsule in bacteria

A

•Virulence factor, protecting bacteria from phagocytosis by immune cells(has the most angtigenic variations) e.g Streptococcus pneumoniae .
•Permit bacteria, to adhere to cell surfaces and structures such as medical implants, catheters and so on.
•Capsules can be a source of nutrients and energy to microbes
•Prevents cell from drying out (desiccation)
•Polysaccharides from certain capsules is antigenic and can elicit production of protective antibodies

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31
Q

What is the point of adherence in bacteria

A

•Adherence is an important first step in colonization and sometimes leads to disease.

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32
Q

What is capsule made up of

A

Capsular antigen

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33
Q

Example of capsule being a source of nutrients and energy for bacteria

A

Streptococcus mutans, which colonizes teeth, ferments the sugar in the capsule and the acid byproducts contribute to tooth decay.

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34
Q

Examples of capsules that are highly antigenic

A

Included in vaccines
•Such a vaccine is used against Hemophilus influenzae , Streptococcus pneumoniae and Neisseria meningitidis.

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35
Q

Describe the DNA of bacteria

A

the cytoplasm contains DNA, which is typically a single circle concentrated in a nucleoid region and not membrane bound

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36
Q

Describe how the genetic information of bacteria are Carried

A

Genetic information is carried in a long double stranded DNA. This is the chromosome, which comprise genes.
• Genetic information may also be extrachromosomal, present as plasmid

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37
Q

What are the plasmids I’m the bacteria

A

Small, extrachromosomal DNA circles.

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38
Q

How do plasmids replicate

A

•Plasmids replicate independently of the chromosome

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39
Q

What’s the function of a plasmid in a bacteria

A

carry genes that are not essential for cell survival but may give some advantage to an organism e.g they can carry genes for antibiotic resistance and toxin production.

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40
Q

What is a pili in bacteria

A

project from the cell wall but are more rigid than the flagella.
•Also called fimbriae

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41
Q

Functions of pili In bacteria

A

They function in attachment to host cells (act as adhesins)
•They prevent phagocytosis

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42
Q

What kind of bacteria are pili seen In more

A

Present in many Gram negative bacteria
◦e. g Neisseria gonorrhoea uses its fimbriae to attach to the lining of the genital tract and initiate an STD

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43
Q

What are the 2 types of pili

A

Somatic pili
Sex pili (F pili)

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44
Q

Which pili is used for conjugation

A

F. Pili

Sex pili act to join bacterial cells for transfer of DNA from one cell to another (bacterial conjugation)

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45
Q

Functions of fibriae (other than prevent phagocytes and for adhesion)

A

•Fimbriae also act as receptors for viruses that infect bacteria (bacteriophages)
•Fimbriae and cell walls of Streptococcus pyogenes are coated with M protein.

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46
Q

Function of M protein in bacteria

A

•M protein acts as an important virulence factor by adhering to host cells and resisting phagocytosis

47
Q

Why can some substances pass through the thick peptidoglycan in gram+ bacteria

A

•Gram positive thickly meshed peptidoglycan layer does not block diffusion of low molecular weight compounds so, some substances (antibiotics, dyes, detergents), can pass through

48
Q

Can antibiotic and chemicals pass through the gram- cell wall

A

No

49
Q

Why is the dark blue color retained in gram+ bacteria

A

Crystal violet is trapped in the thick peptidoglycan layer

50
Q

What is the dark blue color not retained in gram- Bacteria

A

The outer cell membrane of the Gram negative cell wall is partially destroyed by alcohol, so crystal violet is washed out and a counterstain can be taken

51
Q

Virulence of bacteria depends on what certain cell structures

A

Pili
Flagella
Capsule

52
Q

Describe the staining mechanism

A

•Pour crystal violet (60 secs)
•Wash off with water and flood with Lugols iodine (60 secs)
•Wash off with water and decolorise with 95% alcohol
•Counterstain with safranin (60 secs) and wash off with water

53
Q

Describe the gram+ staining characteristics

A

Cells that absorb the crystal violet and hold onto it-
•they stain blue or purple or black.

54
Q

Describe the gram- staining characteristics

A

If the cells do not absorb crystal violet, it is washed off by the alcohol, the cells will then absorb safranin or dilute carbol fuschin
•Gram negative organisms stain pink or red

55
Q

How do medically important bacteria produce energy

A

Medically important bacteria use chemical and organic compds as energy source to produce ATP

56
Q

How do obligate intracellular organisms produce energy

A

not capable of metabolic pathways, so get ATP from host cells

57
Q

How do obligate intracellular bacteria form energy

A

not capable of metabolic pathways, so get ATP from host cells

58
Q

Examples of obligate intracellular bacteria

A

•Chlamydia, Rickettsia

59
Q

What are the metabolic characteristics of bacteria

A

•Obligate aerobes
•Facultative anaerobes
•Microaerophilic
•Obligate anaerobes

60
Q

What are the major classes of bacteria

A

•Gram positive bacilli
•Gram positive cocci
•Gram negative bacilli
•Gram negative cocci
•Others

61
Q

Which group of bacteria is the largest group

A

Gram negative bacilli

62
Q

What is a gram+ cocci catalase+ bacteria

A

Staphylococcus

63
Q

List out the gram+ coccus bacteria

A

• Staphylococcus
(S Aureus is coag +ve)
S. Epidermis is coag -ve
• Streptococcus
• Enterococcus

• Strep Viridian’s (anaerobic)

64
Q

Which gram + coccus bacteria is anaerobic

A

Strep Viridian’s

65
Q

What are the gram + bacillus bacteria

A

•Bacillus
•Listerium
•Nocardia
•Coryne bacteria
• Actinomyces
• Clostridium
• Lactobacillus

66
Q

Which gram+ bacillus bacteria is anaerobic

A

• Actinomyces
• Clostridium
• Lactobacillus

67
Q

Which gram+ bacillus bacteria is aerobic

A

•Bacillus
•Listerium
•Nocardia
•Coryne bacteria

68
Q

What are the gram - cocci bacteria

A

• Moraxella
• Neisseria

69
Q

Are Moraxella and Neisseria aerobic or anaerobic

A

Aerobic (gram- cocci)

70
Q

What are the gram- bacillus bacteria

A

• Haemophillus
• Klebsiella
• Proteus
• Acinectobacter
• Pseudomonas
• Yersinia
• Salmonela
• Campylobacter
• Enterobacter
• Morganella
• Bacteriodes

71
Q

Which of the gram- bacillus bacteria is anaerobic

A

Bacteriodes

72
Q

Which bacteria is too small to be seen with light the microscope

A

Spirochetes

73
Q

Which bacteria is acid fast stain

A

Mycobacteria

74
Q

Which bacteria is without cell wall, only cell membrane

A

Mycoplasma

75
Q

What are the antigens in a bacteria

A

•O (somatic) antigens to classify Gram negative bacilli
•O antigen, H (flagella) antigen and Vi (capsular)
•Over 2000 serotypes of Salmonella
•M protein classifies S. pyogenes into >80 types
•Cell wall carbohydrate antigen is used to group the Streptococci

76
Q

What does M protein classify

A

S. pyogenes into >80 types

77
Q

What is Cell wall carbohydrate antigen used to classify

A

Streptococcus

78
Q

What are O antigens used to classify

A

Gram- bacteria

79
Q

What are the basic characteristics and identifying features of bacteria

A

•Colony shape/xteristic in culture
•Haemolytic patterns (α, β, non)
• pigmented
•Specialised structures like flagella, spores, capsule
•Biochemical reactions to ascertain presence of metabolic activity
•Fermentation (fermentative & non-fermentative bacilli)
•Motility
•oxidase reaction
•Indole reaction
•Urease production
•Hydrogen sulphide production

80
Q

What do you need to test the motile of a bacteria

A

Hanging drop test

81
Q

What are the 3 types of hemolytic pattern in a bacteria

A

B-hemolysis
alpha-hemolysis
Gamma-hemolysis

82
Q

What is beta hemolysis

A

Complete hemolysis
(Clear area when bacteria is dropped)

83
Q

What are the 2 examples of beta hemolysis

A

GAS- Group A Streptococci
GBS- Group B streptococci

84
Q

What is alpha hemolysis

A

Partial hemolysis
(Greenish area where bacteria is dropped)

85
Q

Example of alpha hemolysis

A

Streptococcus viridans

86
Q

What is gamma hemolysis

A

No hemolysis

87
Q

Example of gamma hemolysis

A

Peptostreptococcus
Enterostreptococcus

88
Q

How do you detect a bacteria

A

•Culture
•Cell free media – colonial morphology on culture media
•Microscopy
•Stains -Gram stain (morphology), giemsa stain ricketsia –light microscopy
•Wet prep - phase contrast or dark-field microscopy

•Serology
•Agglutination, CFT, fluorescent antibody test, PCR etc
•Antigen detection
•Latex agglutination
•DNA based techniques

89
Q

How can you classify bacteria based on their oxidase reaction

A

Obligate aerobic
Obligate anaerobic
Facultative anaerobic
Microarrophilic

90
Q

Examples of bacteria that cannot be stained

A

Mycobacteria, including M. tuberculosis
Treponema pallidum
Mycoplasma pneumoniae
Legionella pneumophila
Chlamydiae, including C. trachomatis

91
Q

Examples of bacteria that cannot be stained

A

•Rickettsiae
•Mycobacteria, including M. tuberculosis
•Treponema pallidum
•Mycoplasma pneumoniae
•Legionella pneumophila
•Chlamydiae, including C. trachomatis

92
Q

Why can’t mycobacteria be stained

A

Too much lipid in cell wall so dye cannot penetrate

93
Q

What is used for mycobacteria instead of regular stain

A

Acid-fast stain

94
Q

Why can’t Treponema pallidum be gram stained

A

It’s too thin to see

95
Q

What’s used for treponema pallidum instead of gram stain

A

Dark-field microscopy or fluorescent antibody

96
Q

Why can’t Mycoplasma pneumoniae be gram stained

A

No cell wall
Very thin

97
Q

What is used for Mycoplasma pneumoniae instead of gram stain

A

Nothing

98
Q

Why can’t Legionella pneumophila be gram stained

A

Poor uptake of red counterstain

99
Q

What’s used for Legionella pneumophila instead of normal farm stain

A

Prolong time of counterstain

100
Q

Why can’t Chlamydiae, including C. trachomatis be gram stained

A

Intracellular; very small

101
Q

What’s used for Chlamydiae, including C. trachomatis instead of normal gram stain

A

Inclusion bodies in cytoplasm

102
Q

Why can’t Rickettsiae be gram stained

A

Intracellular
Very small

103
Q

What’s used for Rickettsiae instead of normal gram stain

A

Giemsa or other tissue stains

104
Q

Describe the DNA based techniques

A

•A probe is a section of DNA that is meant to adhere to its opposite strand of DNA
•PCR – DNA can be amplified and then identified
• has specificity and high speed capabilities
•DNA sequence of a particular component of their ribosomes
•used as a tool to group bacteria together that are believed to have evolved from a common ancestor.
•Their ribosomal RNA would be very similar (16s RNA)

105
Q

How are bacteria grouped according to how dangerous they are

A

•Pathogens -are always likely to cause disease
•Opportunistic -cause disease only when they have a special opportunity to gain entrance inside the body
•Invasive -proactively create portals of entry -

106
Q

Examples of pathogenic bacteria

A

Salmonella typhi, Vibrio cholerae

107
Q

Examples of opportunistic bacteria

A

Bacteroides fragilis, Clostridium difficile, Pseudomonas aeruginosa

108
Q

Examples of invasive bacteria

A

Salmonella enteritidis,

109
Q

What is present in a gram- bacteria after digestion (losing peptidoglycan)

A

Spheroplast

110
Q

What enzyme is found in the Periplasmic space

A

B-lactamase

111
Q

What is the function of B-lactamase

A

Destroys B-lactams

112
Q

Example of B-lactam drug

A

Penicillin

113
Q

What has the most antigenic variations in a bacteria

A

Capsule

Microbiology FPP (4 decks)

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