Bacterial structure Flashcards
1
Q
cell wall - chemical composition
A
peptidoglican: sugar back bone with peptide side side chains cross-linked by transpeptidase
2
Q
cell wall - function
A
- gives rigid support
- protects against osmotic pressure
- major surface antigen
3
Q
lipotechoic acid –>
A
induce TNF and IL-1
4
Q
lipotechoic acid - area
A
Gram-positive bacteria
anchored to cytoplasmic membrane –> through the cell wall
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)
6
Q
LPS - is composed by
A
Lippid A (inner) O polysaccharide (outer)
7
Q
LPS - function
A
Lipid A –> induce TNF and IL-1
O polysaccharide –> antigen
8
Q
bacteria with LPS (and location)
A
gram (-) (outer membrane)
9
Q
bacterial plasma membrane - structure
A
phospholipid bilayer with embedded proteins (penicillin-binding proteins) and other enzymes lipotechoic acid (only gram +)
10
Q
bacterial plasma membrane - function
A
site of oxidative and transport enzyme
11
Q
function of ribosomes / composed by (in bacteria)
A
protein synthesis (50s and 30s)
12
Q
bacterial periplasm?
A
space between the cytoplasmic membrane and outer membrane in gram (-) bacteria (peptidoglycan in middle)
13
Q
bacterial periplasm function
A
contains many hydrolytic enzymes, including β-Lactamases
14
Q
Pilus/firia function
A
- mediate adherence of bacteria to cell surface
2. sex pilus forms attachment between 2 bacteria during conjunction
15
Q
Pilus/firia - chemical composition
A
glycoprotein
16
Q
bacterial spore - characteristics
A
resistant to dehydration, heat and chemicals
17
Q
bacterial spore - chemical composition
A
- keratin like - coat
- dipicolinic acid
- peptidoglycan
- DNA
18
Q
plasmid contain variety of genes for
A
- antibiotic resistance
- enzymes
- toxins
19
Q
bacterial capsule - function
A
protects against phagocytosis
20
Q
bacterial capsule - chemical composition
A
Organized, discrete polysaccharide layer except Bacillus antrhacis wich contains D-glutamate
21
Q
bacterial capsule - Organized, discrete polysaccharide layer (except Bacillus antrhacis wich contains D-glutamate
A
Bacillus antrhacis wich contains D-glutamate
22
Q
bacterial glycocalyx - function
A
mediates adherence to surfaces, especially foreign surface
23
Q
bacterial glycocalyx mediates adherence to surfaces, especially foreign surface - example
A
indwelling catheters
24
Q
bacterial glycocalyx is composed by
A
a loose network of polysaccharides
25
bacterial structure - what is unique for gram (+)
Lipotechoic acid
26
bacterial structure - what is unique for gram (-)
1. Porins on outer mambrane
2. outer membrane
3. endotoxin/LPS
4. periplasmic space
27
gram + with endotoxin/LPS
Listeria monocytogenes
28
flagellum - gram + or - ? / function / chemical composition ?
both
function: motility
chemical composition: protein
29
peptidoclycan is AKA
murein
30
bacterial taxonomy - groups according to morphology
1. spherical (coccus)
2. rob (bacillus)
3. Branching filamentous
4. Pleomorphic
5. spiral
6. no cell wall
31
bacterial taxonomy - spherical and rob AKA
spherical --> coccus
| rob --> bacillus
32
bacterial taxonomy - gram + coccus
1. staphylococcus
| 2. streptococcus
33
bacterial taxonomy - gram - coccus
1. Moraxella catarrhalis
| 2. Neisseria
34
bacterial taxonomy - gram negative robs are divided to (according to their action/origin)
1. enterics
2. respiratory
3. zoonotic
35
bacterial taxonomy - branching filamentous bugs and gram?
gram +
1. actinomyces
2. nocardia
36
bacterial taxonomy - pleomorphic - gram and bugs ?
gram -
1. chlamydiae
2. Rickettsiae
37
bacterial taxonomy - spiral - bags and gram?
gram -
| spirochetes (Borrelia, Leptospira, Treponema)
38
respiratory gram negative robs?
1. Bordetella
2. Haemophilus
3. Legionella
4. Burkholderia cepacia
39
zoonotin gram negative robs?
1. Bartonella
2. Brucella
3. Francisella
4. Pasteurella
40
bacterial taxonomy - no cell walls
1. Mycoplasma
| 2. ureoplasma
41
bacteria with no cell wall - special characteristic
contain sterols, which do not gram stain
42
how do bacterial cell membranes differ from mammalian cell membranes
Bacterial cell membranes lack sterols (except Mycoplasma, Ureaplasma)
43
Gram stain limitations for bugs means
these bugs do not gram stain well
44
Gram stain limitations - bugs?
```
Mnemonic: These Microbes May Lack Real Color
Treponema (and leptospura)
Mycobacteria (and ureoplasma)
Legionella pneumonophila
Rickettsia
Chlamydia
(+ BARTONELLA, ehrlichia, anaplasma)
```
45
Gram stain limitations - treponema - mechanism
too thin to be visualized
46
Gram stain limitations - Mycoplasma - mechanism
no cell wall
47
Gram stain limitations - legionella pneumophila - mechanism
primarily intracellular
48
Gram stain limitations - Rickettsia - mechanism
intracellular parasite
49
Gram stain limitations - Chlamydia - mechanism
1. intracellular parasite
| 2. lacks classic peptidoglycan because of low muramic acid
50
how to see treponemes
dark field microscopy
and
fluorescent antibody staining
51
microbiology - types of stains
1. Giemsa
2. PAS
3. Ziehl-Neelsen
4. India INK
5. Silver stain
52
Giemsa stain - microbes?
```
Mnemonic - Certain Bugs Really TRY my Patience
Chlamydia
Borrelia
Rickettsia
TRYpanosomes
Plasmodium
```
53
PAS stain? (means) / (which substance)
periodic acid-Schiff
1. glycogen
2. mucopolysaccharides
54
PAS is used to
diagnose Whipple disease (Tropheryma Whipplei)
55
Ziehl-Neelsen (carbol fuschin) stains
Acid-Fast bacteria (Nocardia, Mycobaceria) and protozoa (Cryptosporidium oocysts)
56
protozoa that are stained by Ziehl-Neelsen
Cryptosporidium oocysts
57
Ziehl-Neelsen - alternative stain?
auramine - rhbamine stain
58
auramine - rhbamine stain is Ziehl-Neelsen alternative for ... (why)
screening (inexpensive, more sensitive but less specific)
59
mycobacteria - special characteristic of the structure (and clinical relevance)
cell wall are high in mycolic acid - detected by carbolfuchin in acid-fast stain
60
india ink stains
Cryptococcus neoformans
61
Cryptococcus neoformans is stained by
1. India ink
| 2. Mucicarmine
62
Cryptococcus neoformans - mucicarimine - mechanism
stain thick polysaccharide capsule red
63
silver stain is used to stain
1. Fungi (eg. Pneumocytosis)
2. Legionella
3. Helicobacter pylori
64
Special culture requirements - H. influenza - media (and its contains)?
Chocolate agar - Factor V (NAD+) and X (hematin)
65
Special culture requirements - Neisseria - media (and its contains)?
Thayer - Martin - vancomicin , trimethoprim, colistin , nystatin
66
Thayer - Martin contains ... (and action)
1. vancomicin --> inhibits gram (+)
2. trimethoprim
3. colistin --> inhibits gram (-) except Neisseria
4. nystatin --> inhibits fungi
67
Special culture requirements -Bordetella Pertussis - media (and its contains)?
1. Bordet-Gengou agar (potato)
| 2. Regan-Lowe medium (Charcoal, blood, antibiotic)
68
Special culture requirements - Corynebacterium diphtheriae - media ?
Tellurite agar and Loffler medium
69
Special culture requirements - Mycoplasma Pneumoniae - media (and its contains)?
Eaton agar --> cholesterol (because Mycoplasma requires sterols)
70
Mycoplasma - special charactersitics
no cell wall
| contains sterols
71
Special culture requirements - Lactose-fermenting enterics - media?
MacConkey agar
72
MacConkey agar - mechanism
Lactose fermenting enterics --> fermentation produce acid causing colonies to turn PINK
73
Special culture requirements - E-coli - media?
1. Eosin methylene blue (EMB) agar
| 2. it also lactose fermenting (not all strains)
74
E-coli in Eosin methylene blue agar -->
colonies with green metallic sheen
75
Special culture requirements - Legionella - media?
charcoal yeast extract agar buffered with cysteine and iron
76
Special culture requirements - Fungi - media?
Sabouraud agar
77
Bordet-gengou agar - bugs
Bordetella Pertussis
78
Special culture requirements - Mycobabterium Tuberculosis - media?
Lowenstein-Jensen agar
79
media with charcoal, blood, antibiotis (and bugs)
Regan-Powe medium - Bordetella Pertussis
80
Sabouraud agar - bugs
Fungi
81
Chocolate agar - contains and bugs
```
contains V (NAD+) and X (hematin)
H. influenzae
```
82
potato agar? (and bug)
Bordet-Gengou agar
| Bordetella Pertussis
83
colonies with green metallic sheen - media and bug
Eosin methylene blue (EMB) agar
| E-coli
84
charcoal yeast extract agar buffered with cysteine and iron - bug?
Legionella
85
bacteria are divided to ... (according to O2 use)
1. aerobes
| 2, anaerobes
86
aerobes bacteria - mechanism
use an O2 dependent system to generate ATP
87
aerobes bacteria - examples (3)
1. Nocardia
2. Pseudomonas
3. Mycobacterium Tuberculosis
88
factors that induce M. Tuberculosis reactivation
1. immunocompromise
| 2. TNF-α inhibitors
89
Reactivation of M. Tuberculosis has a predilection for the .... (location) (why)
apices of the lung, which have the highest PO2
90
anaerobe bacteria - examples (4)
1. fusobacterium
2. Clostiridium
3. Bacteroids
4. Actinomyces
91
anaerobe bacteria lack ..... and thus ....
catalase and/or superoxide dismutase and thus susceptible to oxidative damage
92
anaerobes - smelling (and mechanism)
foul smeling - short (volatile short-chain fatty acids)
93
anaerobes - culturing
very difficult
94
anaerobes prodce
gas in tissue (CO2 and H2)
95
anaerobes in the body
normal flora in GI tract
| typically pathogenic elsewhere else
96
anaerobes and aminoglycosides
aminoglycosides are ineffective against anaerobes because these antibiotics require 02 to enter into bacterial cell
97
Intracellular bugs are divided to
1. Obligate intracellular
| 2. Facultive intracellular
98
Obligate intracellular bugs - characteristic and bugs
rely on host ATP
1. Rickettsia
2. Chlamydia
3. Coxiella
99
Facultive intracellular - bugs?
1. Salmonella 2. Neisseria 3. Brucella 4. Mycobacterium
| 5. Listeria 6. Francisella 7. Legionella 8. Yersinia pestis
100
Encapsuled bacteria - examples
1. Streptococcus pneumoniae
2. Haemophilus influenzae type B
3. Neisseria meningitidis
4. E. coli
5. Salmonella
6. Klebsiella pneumoniae
7. group B strep
101
Encapsuled bacteria - their capsule serve as an
anthiphagocytic viruence factor
102
Encapsuled bacteria - clinically relevance
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
Encapsuled bacteria - asplenic
asplenic have decreased opsonizing ability and thus high risk for severe infections
104
asplenic patients - vaccines?
1. S. pneumoniae
2. H. influenzae type B
3. N. meningitidis
105
Encapsuled bacteria - vaccines mechanism
Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, enchancing immunogenicity by promoting T-cell activation and subsequent class switching.
106
asplenic patients - vaccines - structure
1. S. pneumoniae --> PCV conjugate, PPSV non congugate
2. H. influenzae type B--> conjugate
3. N. meningitidis --> conjugate
107
S pneumoniae - vaccines and structure
PCV - pneumonococcal congugate vaccine (Prevnar)
| PPSV - pneumonococcal polysaccharide vaccine with no congugate protein (Pneumovax)
108
Urease-positive organisms / action of urease
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
bacterial catalase - mechanism
degrades H2O2 into H20 and bubbles of O2 before it can be converted to microbicidal products products by the enzyme peroxidase
110
Chronic granoulomatous disease - pathophysiology
NADPH oxidase deficiency
111
NADPH oxidase - action
O2 + NADPH --> NADP+ + O2- (superoxide anion)
112
people with Chronic granoulomatous disease have recurrent infection of with .... (why)
CATALASE + organism
even without NADPH they can convert H2O2 produced by bacteria
CATALASE + organism degrade their H2O2
113
CATALASE + organism - examples
PLACESS (+ nocardia, H. pylori, B. cepacia
1. Staphylococci 2. E-coli 3. Candida
4. Serratia 5. Listeria 6. Aspergillus
7. Pseudomonas 8. Nocardia
114
Catalase + non bacterial organisms?
1. Candida
| 2. Aspergillus
115
Pigmented - producing bacteria / pigmented?
1. Staphylococcus aureus --> yellow
2. Pseudomonas aeroginosa --> blue green
3. Serratia marcencens --> red
4. Actinomyces israelli --> yellow "sulfur" granules
116
Bacterial virulence factors - action
promote evasion of host immune response
117
Bacterial virulence factors - types
1. Protein A
2. IgA protease
3. M protein
118
Bacterial virulence factors - Protein A is expressed by
Staphylococcus aureus
119
Bacterial virulence factors - Protein A?
Binds Fc region of IgG --> prevent opsonization and phagocytosis
120
Bacterial virulence factors - IgA protease is secreted by
1. S. pneumoniae
2. H. influenzae type B
3. Neisseria
121
Bacterial virulence factors - IgA protease - action
enzyme that cleaves IgA, in order to colonize respiratory mucossa
122
Bacterial virulence factors - M Protein is expressed by
group A streptococci
123
Bacterial virulence factors - M Protein - action
Helps prevent phagocytosis
124
Bacterial virulence factors - M Protein - clinical relevance
Share similar epitopes to human cellular proteins (protein mimicry --> possibly underlines the autoimmune response in acute rheumatic fever
125
Bacterial virulence factors - types and expression by
1. Protein A --> S. aureus
2. IgA protease --> S. pneumoniae, H. influenzae type B, Neisseria
3. M protein --> group A streptococci
126
Type III secretion system is AKA
injectisome
127
Type III secretion system (injectisome)
''Needle-like'' protein appendage facilitating direct delivery of toxins from certain gram (-) bacteria INTO eukaryotic host cell
128
Type III secretion system (injectisome) - which bacteria (and example)
```
certain gram (-) bacteria
example: pseudomonas, Salmonella, Shigella, E-coli
```
129
spore forming bacteria - bugs and diseases
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
Some bacteria can form spores at the (phase)
end of stationary phase when nutrients are limited
131
How to kill spores
Must autoclave to potentially kill spores (as in done to surgical equipment by streaming at 121 C for 15 min
132
bacterial spore - chemical composition
1. keratin like - coat
2. dipicolinic acid
3. peptidoglycan
4. DNA
133
Properties of growth media - explain
1. Selective media 2. Indicator (differential) media
| The same type of media can posses both or neither of these properties
134
Selective media - function
Favors the growth of particular organism while preventing growth of other organism
135
Indicator (differential) media
yields a color change in responde to the medatbolsum of certain organism
