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Microbiology > Bacterial structure > Flashcards

Bacterial structure Flashcards

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1
Q

cell wall - chemical composition

A

peptidoglican: sugar back bone with peptide side side chains cross-linked by transpeptidase

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2
Q

cell wall - function

A
  1. gives rigid support
  2. protects against osmotic pressure
  3. major surface antigen
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3
Q

lipotechoic acid –>

A

induce TNF and IL-1

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4
Q

lipotechoic acid - area

A

Gram-positive bacteria

anchored to cytoplasmic membrane –> through the cell wall

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5
Q

bacteria with outer membrane / function / structure

A

gram (-)

function: 1. site of endotoxin (LPS) 2. major antigen surface (outer membrane proteins) 3. porins: transport accross outer membrane
structure: outer leaflet (endotoxins and embedded proteins), inner leaflet (phospholipids)

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6
Q

LPS - is composed by

A 
Lippid A (inner)
O polysaccharide (outer)
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7
Q

LPS - function

A

Lipid A –> induce TNF and IL-1

O polysaccharide –> antigen

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8
Q

bacteria with LPS (and location)

A

gram (-) (outer membrane)

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9
Q

bacterial plasma membrane - structure

A 
phospholipid bilayer with embedded proteins (penicillin-binding proteins) and other enzymes 
lipotechoic acid (only gram +)
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10
Q

bacterial plasma membrane - function

A

site of oxidative and transport enzyme

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11
Q

function of ribosomes / composed by (in bacteria)

A

protein synthesis (50s and 30s)

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12
Q

bacterial periplasm?

A

space between the cytoplasmic membrane and outer membrane in gram (-) bacteria (peptidoglycan in middle)

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13
Q

bacterial periplasm function

A

contains many hydrolytic enzymes, including β-Lactamases

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14
Q

Pilus/firia function

A
  1. mediate adherence of bacteria to cell surface

2. sex pilus forms attachment between 2 bacteria during conjunction

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15
Q

Pilus/firia - chemical composition

A

glycoprotein

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16
Q

bacterial spore - characteristics

A

resistant to dehydration, heat and chemicals

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17
Q

bacterial spore - chemical composition

A
  1. keratin like - coat
  2. dipicolinic acid
  3. peptidoglycan
  4. DNA
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18
Q

plasmid contain variety of genes for

A
  1. antibiotic resistance
  2. enzymes
  3. toxins
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19
Q

bacterial capsule - function

A

protects against phagocytosis

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20
Q

bacterial capsule - chemical composition

A

Organized, discrete polysaccharide layer except Bacillus antrhacis wich contains D-glutamate

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21
Q

bacterial capsule - Organized, discrete polysaccharide layer (except Bacillus antrhacis wich contains D-glutamate

A

Bacillus antrhacis wich contains D-glutamate

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22
Q

bacterial glycocalyx - function

A

mediates adherence to surfaces, especially foreign surface

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23
Q

bacterial glycocalyx mediates adherence to surfaces, especially foreign surface - example

A

indwelling catheters

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24
Q

bacterial glycocalyx is composed by

A

a loose network of polysaccharides

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25
Q

bacterial structure - what is unique for gram (+)

A

Lipotechoic acid

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26
Q

bacterial structure - what is unique for gram (-)

A
  1. Porins on outer mambrane
  2. outer membrane
  3. endotoxin/LPS
  4. periplasmic space
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27
Q

gram + with endotoxin/LPS

A

Listeria monocytogenes

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28
Q

flagellum - gram + or - ? / function / chemical composition ?

A

both
function: motility
chemical composition: protein

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29
Q

peptidoclycan is AKA

A

murein

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30
Q

bacterial taxonomy - groups according to morphology

A
  1. spherical (coccus)
  2. rob (bacillus)
  3. Branching filamentous
  4. Pleomorphic
  5. spiral
  6. no cell wall
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31
Q

bacterial taxonomy - spherical and rob AKA

A

spherical –> coccus

rob –> bacillus

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32
Q

bacterial taxonomy - gram + coccus

A
  1. staphylococcus

2. streptococcus

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33
Q

bacterial taxonomy - gram - coccus

A
  1. Moraxella catarrhalis

2. Neisseria

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34
Q

bacterial taxonomy - gram negative robs are divided to (according to their action/origin)

A
  1. enterics
  2. respiratory
  3. zoonotic
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35
Q

bacterial taxonomy - branching filamentous bugs and gram?

A

gram +

  1. actinomyces
  2. nocardia
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36
Q

bacterial taxonomy - pleomorphic - gram and bugs ?

A

gram -

  1. chlamydiae
  2. Rickettsiae
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37
Q

bacterial taxonomy - spiral - bags and gram?

A

gram -

spirochetes (Borrelia, Leptospira, Treponema)

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38
Q

respiratory gram negative robs?

A
  1. Bordetella
  2. Haemophilus
  3. Legionella
  4. Burkholderia cepacia
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39
Q

zoonotin gram negative robs?

A
  1. Bartonella
  2. Brucella
  3. Francisella
  4. Pasteurella
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40
Q

bacterial taxonomy - no cell walls

A
  1. Mycoplasma

2. ureoplasma

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41
Q

bacteria with no cell wall - special characteristic

A

contain sterols, which do not gram stain

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42
Q

how do bacterial cell membranes differ from mammalian cell membranes

A

Bacterial cell membranes lack sterols (except Mycoplasma, Ureaplasma)

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43
Q

Gram stain limitations for bugs means

A

these bugs do not gram stain well

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44
Q

Gram stain limitations - bugs?

A 
Mnemonic: These Microbes May Lack Real Color 
Treponema (and leptospura) 
Mycobacteria (and ureoplasma) 
Legionella pneumonophila 
Rickettsia 
Chlamydia 
(+ BARTONELLA, ehrlichia, anaplasma)
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45
Q

Gram stain limitations - treponema - mechanism

A

too thin to be visualized

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46
Q

Gram stain limitations - Mycoplasma - mechanism

A

no cell wall

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47
Q

Gram stain limitations - legionella pneumophila - mechanism

A

primarily intracellular

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48
Q

Gram stain limitations - Rickettsia - mechanism

A

intracellular parasite

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49
Q

Gram stain limitations - Chlamydia - mechanism

A
  1. intracellular parasite

2. lacks classic peptidoglycan because of low muramic acid

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50
Q

how to see treponemes

A

dark field microscopy
and
fluorescent antibody staining

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51
Q

microbiology - types of stains

A
  1. Giemsa
  2. PAS
  3. Ziehl-Neelsen
  4. India INK
  5. Silver stain
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52
Q

Giemsa stain - microbes?

A 
Mnemonic - Certain Bugs Really TRY my Patience 
Chlamydia 
Borrelia
Rickettsia 
TRYpanosomes 
Plasmodium
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53
Q

PAS stain? (means) / (which substance)

A

periodic acid-Schiff

  1. glycogen
  2. mucopolysaccharides
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54
Q

PAS is used to

A

diagnose Whipple disease (Tropheryma Whipplei)

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55
Q

Ziehl-Neelsen (carbol fuschin) stains

A

Acid-Fast bacteria (Nocardia, Mycobaceria) and protozoa (Cryptosporidium oocysts)

56
Q

protozoa that are stained by Ziehl-Neelsen

A

Cryptosporidium oocysts

57
Q

Ziehl-Neelsen - alternative stain?

A

auramine - rhbamine stain

58
Q

auramine - rhbamine stain is Ziehl-Neelsen alternative for … (why)

A

screening (inexpensive, more sensitive but less specific)

59
Q

mycobacteria - special characteristic of the structure (and clinical relevance)

A

cell wall are high in mycolic acid - detected by carbolfuchin in acid-fast stain

60
Q

india ink stains

A

Cryptococcus neoformans

61
Q

Cryptococcus neoformans is stained by

A
  1. India ink

2. Mucicarmine

62
Q

Cryptococcus neoformans - mucicarimine - mechanism

A

stain thick polysaccharide capsule red

63
Q

silver stain is used to stain

A
  1. Fungi (eg. Pneumocytosis)
  2. Legionella
  3. Helicobacter pylori
64
Q

Special culture requirements - H. influenza - media (and its contains)?

A

Chocolate agar - Factor V (NAD+) and X (hematin)

65
Q

Special culture requirements - Neisseria - media (and its contains)?

A

Thayer - Martin - vancomicin , trimethoprim, colistin , nystatin

66
Q

Thayer - Martin contains … (and action)

A
  1. vancomicin –> inhibits gram (+)
  2. trimethoprim
  3. colistin –> inhibits gram (-) except Neisseria
  4. nystatin –> inhibits fungi
67
Q

Special culture requirements -Bordetella Pertussis - media (and its contains)?

A
  1. Bordet-Gengou agar (potato)

2. Regan-Lowe medium (Charcoal, blood, antibiotic)

68
Q

Special culture requirements - Corynebacterium diphtheriae - media ?

A

Tellurite agar and Loffler medium

69
Q

Special culture requirements - Mycoplasma Pneumoniae - media (and its contains)?

A

Eaton agar –> cholesterol (because Mycoplasma requires sterols)

70
Q

Mycoplasma - special charactersitics

A

no cell wall

contains sterols

71
Q

Special culture requirements - Lactose-fermenting enterics - media?

A

MacConkey agar

72
Q

MacConkey agar - mechanism

A

Lactose fermenting enterics –> fermentation produce acid causing colonies to turn PINK

73
Q

Special culture requirements - E-coli - media?

A
  1. Eosin methylene blue (EMB) agar

2. it also lactose fermenting (not all strains)

74
Q

E-coli in Eosin methylene blue agar –>

A

colonies with green metallic sheen

75
Q

Special culture requirements - Legionella - media?

A

charcoal yeast extract agar buffered with cysteine and iron

76
Q

Special culture requirements - Fungi - media?

A

Sabouraud agar

77
Q

Bordet-gengou agar - bugs

A

Bordetella Pertussis

78
Q

Special culture requirements - Mycobabterium Tuberculosis - media?

A

Lowenstein-Jensen agar

79
Q

media with charcoal, blood, antibiotis (and bugs)

A

Regan-Powe medium - Bordetella Pertussis

80
Q

Sabouraud agar - bugs

A

Fungi

81
Q

Chocolate agar - contains and bugs

A 
contains V (NAD+) and X (hematin)
H. influenzae
82
Q

potato agar? (and bug)

A

Bordet-Gengou agar

Bordetella Pertussis

83
Q

colonies with green metallic sheen - media and bug

A

Eosin methylene blue (EMB) agar

E-coli

84
Q

charcoal yeast extract agar buffered with cysteine and iron - bug?

A

Legionella

85
Q

bacteria are divided to … (according to O2 use)

A
  1. aerobes

2, anaerobes

86
Q

aerobes bacteria - mechanism

A

use an O2 dependent system to generate ATP

87
Q

aerobes bacteria - examples (3)

A
  1. Nocardia
  2. Pseudomonas
  3. Mycobacterium Tuberculosis
88
Q

factors that induce M. Tuberculosis reactivation

A
  1. immunocompromise

2. TNF-α inhibitors

89
Q

Reactivation of M. Tuberculosis has a predilection for the …. (location) (why)

A

apices of the lung, which have the highest PO2

90
Q

anaerobe bacteria - examples (4)

A
  1. fusobacterium
  2. Clostiridium
  3. Bacteroids
  4. Actinomyces
91
Q

anaerobe bacteria lack ….. and thus ….

A

catalase and/or superoxide dismutase and thus susceptible to oxidative damage

92
Q

anaerobes - smelling (and mechanism)

A

foul smeling - short (volatile short-chain fatty acids)

93
Q

anaerobes - culturing

A

very difficult

94
Q

anaerobes prodce

A

gas in tissue (CO2 and H2)

95
Q

anaerobes in the body

A

normal flora in GI tract

typically pathogenic elsewhere else

96
Q

anaerobes and aminoglycosides

A

aminoglycosides are ineffective against anaerobes because these antibiotics require 02 to enter into bacterial cell

97
Q

Intracellular bugs are divided to

A
  1. Obligate intracellular

2. Facultive intracellular

98
Q

Obligate intracellular bugs - characteristic and bugs

A

rely on host ATP

  1. Rickettsia
  2. Chlamydia
  3. Coxiella
99
Q

Facultive intracellular - bugs?

A
  1. Salmonella 2. Neisseria 3. Brucella 4. Mycobacterium

5. Listeria 6. Francisella 7. Legionella 8. Yersinia pestis

100
Q

Encapsuled bacteria - examples

A
  1. Streptococcus pneumoniae
  2. Haemophilus influenzae type B
  3. Neisseria meningitidis
  4. E. coli
  5. Salmonella
  6. Klebsiella pneumoniae
  7. group B strep
101
Q

Encapsuled bacteria - their capsule serve as an

A

anthiphagocytic viruence factor

102
Q

Encapsuled bacteria - clinically relevance

A
  1. capsule + protein conjugate serves an as antigen in vaccines
  2. Are opsonized and then cleared by spleen (so increased risk for severe infection in asplenics)
103
Q

Encapsuled bacteria - asplenic

A

asplenic have decreased opsonizing ability and thus high risk for severe infections

104
Q

asplenic patients - vaccines?

A
  1. S. pneumoniae
  2. H. influenzae type B
  3. N. meningitidis
105
Q

Encapsuled bacteria - vaccines mechanism

A

Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, enchancing immunogenicity by promoting T-cell activation and subsequent class switching.

106
Q

asplenic patients - vaccines - structure

A
  1. S. pneumoniae –> PCV conjugate, PPSV non congugate
  2. H. influenzae type B–> conjugate
  3. N. meningitidis –> conjugate
107
Q

S pneumoniae - vaccines and structure

A

PCV - pneumonococcal congugate vaccine (Prevnar)

PPSV - pneumonococcal polysaccharide vaccine with no congugate protein (Pneumovax)

108
Q

Urease-positive organisms / action of urease

A
  1. Cryptococcus
  2. H. pylori
  3. Proteus
  4. Ureoplasma
  5. Nocardia
  6. Klebsiella
  7. S. epidermidis
  8. S. saprophyticus
    UREA –> ammonia + CO2 (high ph) –> ammoniun magnesium phosphate stone
109
Q

bacterial catalase - mechanism

A

degrades H2O2 into H20 and bubbles of O2 before it can be converted to microbicidal products products by the enzyme peroxidase

110
Q

Chronic granoulomatous disease - pathophysiology

A

NADPH oxidase deficiency

111
Q

NADPH oxidase - action

A

O2 + NADPH –> NADP+ + O2- (superoxide anion)

112
Q

people with Chronic granoulomatous disease have recurrent infection of with …. (why)

A

CATALASE + organism
even without NADPH they can convert H2O2 produced by bacteria
CATALASE + organism degrade their H2O2

113
Q

CATALASE + organism - examples

A

PLACESS (+ nocardia, H. pylori, B. cepacia

  1. Staphylococci 2. E-coli 3. Candida
  2. Serratia 5. Listeria 6. Aspergillus
  3. Pseudomonas 8. Nocardia
114
Q

Catalase + non bacterial organisms?

A
  1. Candida

2. Aspergillus

115
Q

Pigmented - producing bacteria / pigmented?

A
  1. Staphylococcus aureus –> yellow
  2. Pseudomonas aeroginosa –> blue green
  3. Serratia marcencens –> red
  4. Actinomyces israelli –> yellow “sulfur” granules
116
Q

Bacterial virulence factors - action

A

promote evasion of host immune response

117
Q

Bacterial virulence factors - types

A
  1. Protein A
  2. IgA protease
  3. M protein
118
Q

Bacterial virulence factors - Protein A is expressed by

A

Staphylococcus aureus

119
Q

Bacterial virulence factors - Protein A?

A

Binds Fc region of IgG –> prevent opsonization and phagocytosis

120
Q

Bacterial virulence factors - IgA protease is secreted by

A
  1. S. pneumoniae
  2. H. influenzae type B
  3. Neisseria
121
Q

Bacterial virulence factors - IgA protease - action

A

enzyme that cleaves IgA, in order to colonize respiratory mucossa

122
Q

Bacterial virulence factors - M Protein is expressed by

A

group A streptococci

123
Q

Bacterial virulence factors - M Protein - action

A

Helps prevent phagocytosis

124
Q

Bacterial virulence factors - M Protein - clinical relevance

A

Share similar epitopes to human cellular proteins (protein mimicry –> possibly underlines the autoimmune response in acute rheumatic fever

125
Q

Bacterial virulence factors - types and expression by

A
  1. Protein A –> S. aureus
  2. IgA protease –> S. pneumoniae, H. influenzae type B, Neisseria
  3. M protein –> group A streptococci
126
Q

Type III secretion system is AKA

A

injectisome

127
Q

Type III secretion system (injectisome)

A

'’Needle-like’’ protein appendage facilitating direct delivery of toxins from certain gram (-) bacteria INTO eukaryotic host cell

128
Q

Type III secretion system (injectisome) - which bacteria (and example)

A 
certain gram (-) bacteria 
example: pseudomonas, Salmonella, Shigella, E-coli
129
Q

spore forming bacteria - bugs and diseases

A
  1. Bacillus antrhacis –> antrax
  2. Bacillus cereus –> Food poisoning
  3. Clostiridium botulinum –> botulism
  4. Clostiridium difficile –> Antibiotic associated colitis
  5. Clostiridium perfingess –> gas gangrene
  6. Clostiridium tetani –> tetanus
130
Q

Some bacteria can form spores at the (phase)

A

end of stationary phase when nutrients are limited

131
Q

How to kill spores

A

Must autoclave to potentially kill spores (as in done to surgical equipment by streaming at 121 C for 15 min

132
Q

bacterial spore - chemical composition

A
  1. keratin like - coat
  2. dipicolinic acid
  3. peptidoglycan
  4. DNA
133
Q

Properties of growth media - explain

A
  1. Selective media 2. Indicator (differential) media

The same type of media can posses both or neither of these properties

134
Q

Selective media - function

A

Favors the growth of particular organism while preventing growth of other organism

135
Q

Indicator (differential) media

A

yields a color change in responde to the medatbolsum of certain organism

Microbiology (25 decks)

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