General Bacteriology Flashcards
1
Q
What are commensals?
A
Microorganisms living on or within humans that do not harm the host under normal circumstances and may even be beneficial
2
Q
How can commensals be beneficial?
A
Inhibiting growth of pathogens
Aiding in digestion
3
Q
Name normal skin flora
A
Staph epidermidis
4
Q
Name normal nasal flora
A
Staph epidermidis
5
Q
Name normal oropharyngeal flora
A
Viridans group strep
6
Q
Name normal flora of dental plaques
A
Strep mutans
7
Q
Name normal gut flora
A
E coli
Bacteroides
8
Q
Name normal vaginal flora
A
Lactobacillus acidophilus
9
Q
Name normal lung flora
A
Neisseria catarrhalis
Alpha hemolytic strep
Staph
Non-pathogenic corynebacteria
Candida albicans
10
Q
What are transient flora and give examples
A
Microorganisms that are temporarily present
E coli or s aureus on the hands
11
Q
How can pathogens be differentiated?
A
Facultative versus obligate pathogens
12
Q
What are facultative pathogens?
A
Microorganisms capable of survival outside of a host
13
Q
Give examples of facultative pathogens
A
E coli
Vibrio cholera
Pseudomonas aeruginosa
14
Q
Give examples of opportunistic pathogens
A
Oral candida
PJP
CMV
Cryptococcus
Toxoplasma encephalitis
15
Q
What are obligate pathogens?
A
Microorganisms that can only replicate inside the cells of a host and therefore must infect a host to survive
16
Q
Give examples of obligate pathogens
A
Salmonella
T pallidum
Mycobacterium tuberculosis
17
Q
Which fatty acid can be found in the cell walls of acid fast bacteria?
A
Mycolic acid
18
Q
Which enzyme cross links peptide side chains?
A
Transpeptidase
19
Q
What is peptidoglycan?
A
A polymer chain of the sugars, n-acteyl-muramic acid and n-acetyl-glucosamine, and amino acids
20
Q
What does lipoteichoic acid stimulate the release of?
A
TNF-alpha
IL-1
IL-6
21
Q
Which endotoxin does the outer membrane of gram negative bacteria contain?
A
Lipopolysaccharide (LPS)
21
Q
What is LPS composed of?
A
Lipid A
Core polysaccharide
O antigen
22
Q
Which component of LPS is antigenic?
A
Lipid A
23
Q
What does lipid A stimulate the release of?
A
TNF-alpha
IL1
IL6
24
Which layer are penicillin binding proteins found in?
Cytoplasmic membrane
25
The cytoplasmic membrane is __________ (hydrophobic/hydrophilic)?
Hydrophobic
26
The bacterial capsule is __________ (hydrophobic/hydrophilic)?
Hydrophilic
27
Which polypeptide component does bacillus anthracis contain in its bacterial capsule?
Poly-D-glutamate
28
What does the bacterial capsule protect against?
Phagocytosis
Complement mediated lysis
29
What is a glycocalyx?
A glycoprotein-polysaccharide layer that covers the cell membrane
30
What is the function of the glycocalyx?
Adhesion of bacteria to cell and foreign surfaces
31
What does the periplasm contain?
Beta lactamase
32
Which bacteria are spore formers?
Gram positive
33
What does the coating later of endospores contain?
Keratin
Dipicolinic acid
Peptidoglycan
DNA
34
What do endospores protect against?
Dehydration
Temperature damage
Chemical damage
35
Give reasons for poor gram staining of atypical bacteria
Lack of cell wall
Atypical cell wall composition
Very thin cell wall
Intracellular bacteria
36
Give examples of bacteria lacking a cell wall
Mycoplasma
Ureaplasma
37
Give an example of a bacteria with high lipid percentage in its cell wall
Mycobacteria
38
Give an example of a bacteria lacking peptidoglycan in its cell wall?
Chlamydia
39
Give an example of a bacteria lacking LPS in its cell wall
Treponema
40
Give an example of a bacteria with a very thin cell wall
Leptospira
41
Name the two types of acid fast staining
Ziehl Neelsen (red)
Auramine rhodamine (yellow-red)
42
Which element of acid fast bacteria is stained?
Mycolic acid in the cell wall
43
Differentiate between obligate and facultative intracellular bacteria
Obligate - cannot produce ATP outside of host cell
Facultative - can produce ATP outside of host cell
44
Give examples of obligate intracellular bacteria
Rickettsia
Chlamydia
Coxiella
44
Give examples of facultative intracellular bacteria
Mycobacterium
Salmonella
Neisseria
Listeria
Francisella
Legionella
Yersinia
Brucella
44
Define obligate anaerobes
Grows only in absence of oxygen
45
Why are obligate anaerobes susceptible to oxidative damage
Lack of enzymes that can detoxify oxygen radicals
45
Why do obligate anaerobes often produce a foul smell?
Short chain fatty acids and gases (CO2 and H2)
46
Define facultative anaerobes
Can use oxygen for ATP generation but may switch to anaerobic metabolism when necessary
47
Give examples of obligate anaerobes
Foul Anaerobes Can't Breathe
Fusobacterium
Actinomyces israelii
Clostridium
Bacteroides
48
Give examples of aerobic bacteria
Pseudo aeruginosa
Myco tuberculosis
Bordetella pertussis
Nocardia
49
Why is alpha hemolysis green?
Hemoglobin partially oxidized by hydrogen peroxide to methemoglobin which contains biliverdin
50
Give examples of alpha hemolytic bacteria
S pneumo
S viridans
51
Give examples of beta hemolytic bacteria
S aureus
S pyogenes
S agalactiae
52
Which bacteria in the Lancefield grouping falls under Group A?
S pyogenes
53
Which bacteria in the Lancefield grouping falls under Group B?
S agalactiae
54
Which bacteria in the Lancefield grouping falls under Group C?
S equisimilis
S equi
S zooepidemicus
S dysgalactiae
55
Which bacteria in the Lancefield grouping falls under Group D?
Enterococci
S bovis
56
Which bacteria in the Lancefield grouping falls under Group E?
S milleri
S mutans
57
Which bacteria in the Lancefield grouping falls under Group F?
S anginosus
58
Which bacteria in the Lancefield grouping falls under Group G?
S canis
S dysgalactiae
59
Which bacteria in the Lancefield grouping falls under Group H?
S sanguinis
60
Which bacteria in the Lancefield grouping falls under Group L?
S dysgalactiae
61
Which bacteria in the Lancefield grouping falls under Group N?
Lactococcus lactis
62
Which bacteria in the Lancefield grouping falls under Group R & S?
Streptococcus suis
63
Which is the only bacteria which exhibits growth in bile esculin agar as well as 6.5% NaCl?
Group D streptococci
64
Discuss the principles of the indole test
Indole test determines the ability of a microorganism to produce indole from the breakdown of tryptophan. Tryptophan is hydrolyzed by tryptophanase to produce indole, pyruvate or ammonium ion. Indole reacts with Kovac's agent under acidic conditions to produce a red dye
65
Explain Kovac's agent
Contains para-dimethylaminobenzaldehyde and isoamyl alcohol
Para-dimethylaminobenzaldehyde reacts with indole to produce rosindole red dye
Isoamyl alcohol forms a complex with the dye causing it to precipitate
66
What colour does indole positive turn?
Pink
67
What colour does indole negative stay?
Yellow
68
What is an antibiogram?
Microbiological test that assesses the susceptibility of pathogen to various antibiotics
69
What is MIC?
Lowest concentration of antimicrobial that inhibits the growth of a specific microorganism isolate
70
What is generation time?
Time required by bacteria to double in number in a culture
71
What does generation time depend on?
Species of bacterium
Type of culture medium
72
Specify types of culture media
Selective media
Indicator media
73
What does Thayer-Martin agar contain?
Vancomycin (inhibits gram +)
Trimethoprim (inhibits gram -)
Colisitin (inhibits gram -)
Nystatin (inhibits fungi)
74
Which pathogen is isolated using Thayer-Martin agar?
Neisseria spp
75
Describe the colony morphology of neisseria gonorrhoea
Small size
Define margins
Mucoid appearance
Colourless/grayish-white colonies
Smooth consistency
76
Describe the colony morphology of neisseria meningitidis
Medium to large
Mucoid appearance
Blue-gray colour
77
What does MacConkey agar contain?
Lactose
Bile salts
Sodium chloride
pH indicator
78
What does MacConkey agar isolate?
Lactose fermenters
79
Describe the colony morphology of lactose fermenters
Pink colonies (fermentation to hydrogen sulphide which is acidic)
80
Which pathogen is isolated on Bordet-Gengou agar?
Bordetella pertussis
81
What does Bordet-Gengou agar contain?
Potato extract
Sheep blood
Glycerol
82
Describe the colony morphology of bordetella pertussis on Bordet-Gengou agar
Small
Round
Shiny
Mercury-silver appearance
83
Which pathogen is isolated on Regan-Lowe medium?
Bordetella pertussis
84
What does Regan-Lowe medium contain?
Blood
Charcoal
Antibiotics
85
Describe the colony morphology of bordetella pertussis on Regan-Lowe medium
Small
Glistening
Greyish-white
86
Which pathogen is isolated on chocolate agar?
Haemophilus influenza and fastidious organisms
87
What does chocolate agar contain?
X factor (haematin)
V factor (NAD+)
88
What is NAD?
Nicotinamide adenine dinucleotide
89
Describe the colony morphology of haemophilus influenzae on chocolate agar
Small
Pale-grayish
Mucoid
Coccobacillary shape
90
Which pathogen is isolated on Eaton agar?
Mycoplasma pneumonia
91
What does Eaton agar contain?
Cholesterol
92
Describe the colony morphology of mycoplasma pneumonia on Eaton agar
Fried egg appearance
93
Which pathogen is isolated on cystine-tellurite agar?
Corynebacterium diptheriae
94
What does cystine-tellurite agar contain?
Animal tissue
Sodium chloride
L-cystine
Sodium thiosulfate
95
Describe the colony morphology of corynebacterium diptheriae on cystine-tellurite agar
Black colonies with a brown halo
96
Which pathogen is isolated on Loffler medium?
Corynebacterium diptheriae
97
What does Loffler medium contain?
Dextrose
Beef extract
Horse extract
Sodium chloride
Proteose peptone
98
Describe the colony morphology of corynebacterium diphteriae on Loffler medium
Cream-coloured
Raised centers
Dark blue metachromatic granules with methylene blue stain
99
Which pathogen is isolated on eosin methylene blue agar?
E coli
100
What does eosin methylene blue agar contain?
Lactose
Dipotassium phosphate
Eosin
Methylene blue
101
Describe the colony morphology of e coli on eosin methylene blue agar
Green metallic sheen
102
Which pathogens are isolated on charcoal yeast extract agar
Legionella
Pastuerella
Brucelle
Francisella
103
What does charcoal yeast extract agar contain?
Charcoal
Yeast
Cysteine
Iron
104
Describe the colony morphology of legionella on charcoal yeast extract agar
Smooth surface
Precise edges
White-gray to blue-gray
105
Describe the colony morphology of pastuerella on charcoal yeast extract agar
Moderate size
Smooth
Greyish
106
Describe the colony morphology of brucella on chocolate yeast extract agar
Small
Smooth
Slightly yellowish
107
Describe the colony morphology of francisella
Tiny
Pinpoint
Gray-white, translucent or opaque
108
Which pathogen is isolated on Lowenstein-Jensen agar?
M. tuberculosis
109
What does Lowenstein-Jensen agar contain?
Potato extract
Egg suspension
Asparagine
Glycerol
Malachite green
Penicillin
Nalidixic acid
110
Describe the colony morphology of m tuberculosis on Lowenstein-Jensen agar
Small
Brownish
Granular
"Buff, rough and tough"
111
Which pathogen is isolated on Middlebrook agar?
M tuberculosis
112
What does Middlebrook agar contain?
Inorganic salts
Oleic acid
Albumin
113
Describe the colony morphology of m tuberculosis on Middlebrook agar
Small
Brownish
Granular
"Buff, rough and tough"
114
Which pathogen is isolated on Hektoen enteric agar?
Enteric eg salmonella, shigella
115
What does Hektoen enteric agar contain?
Proteose peptone
Sugars (lactose, sucrose, salicin)
Sodium thiosulfate
Iron ammonium citrate
116
Describe the colony morphology of salmonella on Hektoen enteric agar
Black colonies
117
Describe the colony morphology of shigella on Hektoen enteric agar
Green colonies
118
Which pathogen is isolated on triple sugar iron agar?
Enteric bacteria eg salmonella, shigella
119
What does triple sugar iron agar contain?
Fermentable sugars (lactose, sucrose, glucose)
Iron
120
Which pathogen is isolated on mannitol salt agar?
Gram positives (specifically staph spp)
121
What does mannitol salt agar contain?
High level of salt
122
Describe the colony morphology of s aureus on mannitol salt agar
Golden yellow
123
Which pathogen is isolated on bile esculin agar?
S gallolyticus
Enterococcus
124
What does bile esculin agar contain?
Bile
Esculin
Ferric citrate
125
Describe the colony morphology of s gallolyticus and enteroccocus spp on bile esculin agar
Blackening of medium
126
Which pathogen is isolated on thiosulfate citrate bile salts sucrose agar?
Vibrio spp
Enterococcus spp
127
What does thiosulfate citrate bile salts sucrose agar contain?
Sodium thiosulfate
Sodium citrate
Sodium chloride
Saccharose
Proteose peptone
128
Describe the colony morphology of vibrio and enterococcus spp on thiosulfate citrate bile salts sucrose agar
Round
Smooth
Glistening
Slightly flattened
Yellow
129
What is catalase?
An enzyme that breaks down hydrogen peroxide into water and oxygen which prevents its breakdown into microbiocidal substances via myeloperoxidase
130
Name catalase positive organisms
Staphylococci
E coli
Nocardia
Serratia
Listeria
Pseudomonas
Bukholderia cepacia
H pylori
Bordetella pertussis
Candida
Aspergillus
131
Which chronic disease results in recurrent infections with catalase positive organisms?
Chronic granulomatous disease
132
What is coagulase?
An enzyme that converts fibrinogen into fibrin
133
What is oxidase?
An enzyme that catalyzes the donation of hydrogen atoms of oxygen, forming water or hydrogen peroxide
134
Name oxidase positive organisms
Campylobacter
Vibrio
Pseudomonas
Brucella
135
What is oxidase also known as?
Cytochrome c oxidase
136
What is urease?
An enzyme that hydrolyzes urea to ammonia and carbon dioxide, increasing pH
137
Name urease producing organisms
Proteus
H pylori
Ureaplasma
Nocardia
Klebsiella
S epidermidis
S saprophyticus
Cryptococcus
138
Name pigments produced by pseudomonas aeruginosa
Pyoverdin
Pyocyanin
139
What pigment is produced by serratia marcescens?
Red pigment
140
What pigment is produced by actinomyces israelii?
Yellow sulfur granules
141
What pigment is produced by staph aureus?
Yellow pigment
142
Name indirect serology methods
Qualitative antibody detection
Titer development
T cell reaction detection (interferon y release assay)
143
Define plasmids
Bacterial nonchromosomal DNA fragments that replicate independently from chromosomal replication
144
Define integrons
Bacterial nonchromosomal DNA that cannot replicate independently and require integrase to integrate into chromosomal bacteria
145
Define pathogenicity islands
A group of genes assoc with virulence factors such as adhesins and toxins
146
Name intracellular mechanisms of genetic variability of bacteria
High mutation rate
Homologous recombination
147
What is homologous recombination?
Exchange of larger gene segments between bacteria that have a similar gene sequence
148
Name intercellular mechanisms of genetic variability of bacteria
Bacterial transformation
Bacterial conjugation
Hfr cell mediated conjugation
Bacterial transduction
Bacterial transposition
149
Explain bacterial transformation
Uptake of free segments of naked bacterial DNA released by cell lysis from the surroundings through the cell membrane -> combination of new DNA material with bacterial pre-existing DNA -> degradation of unused DNA -> expression of new genes -> transformation
150
Name bacteria that undergo transformation
Neisserie
Haemophilus influenzae type B
Strep pneumo
151
Explain bacterial conjugation
Transfer of plasmids by a bridge-like connection between 2 bacteria
152
What is F factor?
Fertility factor, a bacterial plasmid that enables transfer of genetic material between bacteria
153
What are Hfr cells?
High frequency recombination cells
Bacteria with a conjugative plasmid integrated into their chromosomal DNA
154
Explain conjugation mediated by Hfr cells
Hfr bacteria connect with F- bacteria via the sex pilus -> transfer and replication of DNA material on recipient F- bacteria -> new genes on F- bacteria
155
Define bacteriophages
Viruses that only infect bacteria
156
Explain bacterial transduction
The process of gene transfer between bacteria via bacteriophages
Can be generalized or specialized
157
How do generalized and specialized transduction differ?
Generalized - any portion of bacterial genome transferred
Specialized - specific portion of bacterial genome transferred
158
Explain the process of generalized transduction
Bacteriophage attaches to bacterial cell well and injects its DNA into bacterium -> cleavage of bacterial DNA and replication of viral DNA -> formation of new bacteriophages with phage capsids containing fragments of bacterial DNA -> lysis of bacterium and release of bacteriophages -> bacteriophages infect other bacteria
159
Explain the process of specialized transduction
Bacteriophage infects bacteria -> viral DNA incorporated into the bacterial DNA at a specific location but remains inactive (prophage stage) -> upon activation, the viral DNA is replicated and excised from bacterial genome with flanking bacterial DNA -> excised DNA is incorporated in new bacteriophage capsids -> lysis of bacterium and release of new bacteriophages -> bacteriophages infect other bacteria
160
Name toxins that are transferred via specialized transduction
Erythrogenic toxin (s. pyogenes)
Cholera toxin
Diphtheria toxin
Shiga toxin
Botulinum toxin
161
What is bacterial transposition?
Exchange of genetic information via transposons within the genome or between genomes of various bacteria
162
Define transposons
Bacterial DNA sequence that cannot replicate independently
163
Which gene is transferred from VRE enterococcus to VRSA?
vanA gene
164
Which bacteria are capable of bacterial transformation?
SHIN
Strep pneumo
Haemophilus Influenzae
Neisseria
165
How do you calculate virulence?
Dividing number of individuals who become severely ill or die due to an infection by total number of individuals who have contracted the disease
166
Name virulence factors that aid in bacterial colonization
Lipoteichoic acid (LTA)
Bacterial adhesins
Biofilm
Flagella
167
How does LTA increase inflammation?
Functions as a ligand of toll like receptor 2, stimulating TNF-alpha production
168
Name examples of bacterial adhesins
Pertussis toxin
Hemagglutinins
169
What are peritrichous flagella?
Flagella around the bacterium
170
Give an example of a bacterium with peritrichous flagella
E. coli
171
What are lophotrichous flagella?
Several flagella at one pole
172
Give an example of a bacterium with lophotrichous flagella
Pseudomonas
173
What are polar flagella?
One flagellum at one of the bacterial poles
174
Give an example of a bacterium with polar flagella
Vibrio cholerae
175
How does IgA protease assist with colonization of mucous membranes?
Cleaves mucosal IgA
176
Name bacteria with IgA protease
Neisseria
Haemophilus influenzae
S pneumo
177
How does Protein A function?
Found in bacterial cell well
Binds to Fc region of mainly IgG to prevent immunoglobulin binding to complement or host leucocytes -> inhibits phagocytosis, complement fixation and antibody-dependent killing mechanisms
178
How does M protein assist with avoiding the immune system?
Prevents opsonization by C3b -> inhibits phagocytosis and alternative complement activation
179
How is the secretion of siderophores a virulence factor?
Chelate and import iron
180
Give examples of virulence factors
Colonization
Avoidance of immune system
Bacterial nutrition
Antigenic variation
Intracellular survival
Type III secretion system
Inflammatory response
181
Which bacteria inhibits phagosome-lysosome fusion?
M tuberculosis
182
Which bacteria exits phagosomes before fusion occurs?
Listeria monocytogenes
183
Which bacteria have invasins?
Yersinia spp
184
What is an injectisome?
Bacterial appendage that connects bacteria and immune cells and delivers bacterial toxins directly into the cell
185
Which bacteria have injectisomes?
E coli
Salmonella
Yersinia
P aeruginosa
Chlamydia
186
Compare the bacteria type of endotoxins and exotoxins
Endotoxin - gram negative only
Exotoxin - gram negative AND positive
187
Where is the genetic information of endotoxins encoded?
In bacterial chromosome
188
Where is the genetic information of exotoxins encoded?
In the plasmid or bacteriophage
189
How are endotoxins released?
Bacterial lysis
Exocytosis
190
How are exotoxins released?
Actively secreted by living bacteria
191
Are exotoxins heat stable or heat labile?
Heat labile
191
Are endotoxins heat stable or heat labile?
Heat stable
192
Which exotoxins are heat stable?
Some e coli toxins
SEA
SEB
193
What is the antigenicity of endotoxin vs exotoxin?
Endotoxin - low
Exotoxin - high
194
What is the likelihood of causing disease of endotoxin vs exotoxin
Endotoxin - low
Exotoxin - high
195
Which toxins form toxoid that can be modified into a toxoid vaccine?
Exotoxins
196
Name the toxins produced by s pyogenes
Streptolysin O
Erythrogenic exotoxin A
197
What is the mechanism of action of streptolysin O?
Degrades cell membranes, mainly of RBC (beta hemolysis)
198
What is the mechanism of action of erythrogenic exotoxin A?
Binds to beta region of TCR and MHC II -> release TNF alpha, IL1, IL2, INF-y
199
Name toxins produced by s aureus
Toxic shock syndrome toxin (TSST-1)
Exfoliative toxin
Enterotoxin B
200
What is the mechanism of action of TSST-1?
Binds to beta region of TCR and MHC II -> release TNF alpha, IL1, IL2, INF-y
201
What is the mechanism of action of exfoliative toxin?
Damages desmosome proteins of the stratum granulosum -> epidermolysis
202
What is the mechanism of action of enterotoxin B?
Forms pores in enterocyte membranes -> leakage of Na+ and water into intestinal lumen
203
What toxin is produced by c perfringens?
Alpha toxin
204
What is the mechanism of action of alpha toxin?
Acts as a phospholipase -> degrades cell membranes and tissue
205
What toxin is produced by c diphtheriae?
Diphtheria toxin
206
What is the mechanism of action of diphtheriae toxin?
Inactivates EF-2 -> arrested protein translation and synthesis -> cell death and necrosis
207
What toxin is produced by p aeruginosa?
Pseudomonas exotoxin A
208
What is the mechanism of action of pseudomonas exotoxin A?
Inactivates EF-2 -> arrested protein translation and synthesis -> cell death and necrosis
209
What toxin is produced by shigella?
Shiga toxin
210
What is the mechanism of action of shiga toxin?
Removes adenine from rRNA -> inactivation of 60s ribosome -> disrupted protein synthesis -> cell death -> GI mucosal damage -> diarrhea
Enhanced cytokine release -> microthombi that occlude the arterioles and capillaries -> microangiopathic hemolytic anemia, thrombocytopenia, AKI
211
What toxin is produced by enterohemorrhagic e coli (EHEC)?
Shiga-like toxin
212
What is the mechanism of action of shiga-like toxin?
Removes adenine from rRNA -> inactivation of 60s ribosome -> disrupted protein synthesis -> cell death -> GI mucosal damage -> diarrhea
Enhanced cytokine release -> microthombi that occlude the arterioles and capillaries -> microangiopathic hemolytic anemia, thrombocytopenia, AKI
213
Which toxin is produced by enterotoxigenic e coli?
Heat stable toxin
Heat labile toxin
214
Which other organism produces heat labile toxin?
Bacillus cereus
215
What is the mechanism of action of heat stable toxin?
Activation of guanylate cyclase -> incr cGMP -> decr NaCl reabsorption -> water efflux into intestinal lumen -> secretory diarrhea
216
What is the mechanism of action of heat labile toxin?
Overactivates adenylate cyclase -> incr cAMP -> incr secretion of chloride and water efflux into intestinal lumen -> watery diarrhea
217
What toxin is produced by v cholerae?
Cholera toxin
218
What is the mechanism of action of cholera toxin?
Permanently activates Gs protein -> overactivation of adenylate cyclase -> incr cAMP -> incr secretion of chloride and water efflux into intestinal lumen -> watery diarrhea
219
How is the diarrhea caused by cholera described?
Rice water diarrhea
220
What toxin is produced by bacillus anthracis?
Anthrax toxin
221
What is the mechanism of action of anthrax toxin?
1. Edema factor (EF) binds to calcium and calmodulin and gains adenylate cyclase activity -> incr cAMP -> cell edema
2. Lethal factor (LF) destroys MAPKK -> cell death
3. Protective antigen binds to endothelial receptors and facilitates entry of EF and LF into host cells
222
Which toxin is produced by bordetella pertussis?
Pertussis toxin
223
What is the mechanism of action of pertussis toxin?
Causes ADP-ribosylation of the alpha subunit of Gi protein -> inhibition of Gi protein -> adenylate cyclase disinhibition -> cAMP accumulation -> impaired cell signaling pathways
224
Which toxin is produced by c tetani?
Tetanospasmin
225
What is the mechanism of action of tetanospasmin?
Acts as protease that cleaves synaptobrevin (SNARE protein) -> prevention of inhibitory NT release from Renshaw cells in spinal cord -> uninhibited activation of alpha motor neurons -> mm spasms, rigidity, autonomic instability
226
Which toxin is produced by c botulinum?
Botulinum toxin
227
What is the mechanism of action of botulinum toxin?
Acts as a protease that cleaves SNARE proteins and prevents fusion of transmitter-containing vesicles with the presynaptic membrane -> inhibition of Ach release from presynaptic axon terminals
228
Name extrachromosomal genetic mechanisms of drug resistance
Resistance plasmid
Beta lactamase
Acetyltransferase
Protein pumps
