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Infection&immunity > Julie Letch S1 > Flashcards

Julie Letch S1 Flashcards

1
Q

Name 4 sites of action of antimicrobials

A

Cell wall
Protein synthesis
Cell membrane
Nucleic acid synthesis

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2
Q

Do gram negative have a Thinner or thicker layer of peptidoglycan

A

Thinner

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3
Q

What part of the cell do B-Lactams target?

A

Cell wall synthesis

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4
Q

How do B-lactam antibiotics exert their effects?

A

Bind to penicillin binding proteins to prevent X-linking
Mimic D-Ala D-Ala residues on side chain
Indirect effect they stimulate autolysins that break down cell wall

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5
Q

Name two types of antibiotics that exert their effects by acting on cell wall synthesis

A

B-lactams and glycopeptides

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6
Q

Give two examples of a glycopeptide

A

Vancomycin

Teicoplanin

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7
Q

How do glycopeptides exert their effects on cell wall synthesis

A

Binds terminal D-Ala D-Ala on peptide side chain to prevent transglycosylase enzyme from adding PG monomer onto glycan chain, prevents X-linking

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8
Q

Name a class of antibiotics that act on the cell membrane

A

Polymyxins

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9
Q

Give two examples of Polymyxins

A 
Polymyxin B
Polymyxin E (colistin)
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10
Q

How do Polymyxins work

A

Work on cell membrane: cationic binds to lipid A component of gram -ve to distort and increase permeability of outer membrane resulting in leakage

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11
Q

Do Polymyxins work on gram +ve?

A

NO peptidoglycan too thick

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12
Q

Name two antibiotics that are metabolic inhibitors of NUcleic acid synthesis

A

Sulphonamides

Trimethoprim

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13
Q

Name an antibiotic that affects DNA replication

A

Fluroquinolones

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14
Q

Name an antibiotic that affects RNA polymerase

A

Rifamycins

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15
Q

Do nitroimidazoles affect DNA

A

YES

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16
Q

Name two examples of fluoroquinolones that inhibit DNA replication

A

Ciprofloxacin

Levofloxacin

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17
Q

What’s the role of DNA gyrase

A

Removes DNA supercoils ahead of replication fork

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18
Q

What’s the role of topoisomerase IV?

A

Separating DNA after replication

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19
Q

How do the fluoroquinolones inhibit DNA replications

A

They decrease type 2 DNA gyrase and/or type IV topoisomerase

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20
Q

Name two aminoglycosides/oxazolidinones that work by inhibiting protein synthesis

A

Gentamicin

Linezolid

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21
Q

How do most aminoglycosides work?

A

Inhibit protein synthesis by binding to 30S subunit

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22
Q

Do some aminoglycosides and oxazolidinones work by binding to the 50S subunit

A

Yes only some

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23
Q

How do tetracyclines work and give two examples

A

Inhibit protein synthesis by binding to 30S subunit e.g doxycycline and minocycline

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24
Q

How does chloramphenicol work

A

Inhibits protein synthesis by binding 50S subunit and reduces peptide bond formation

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25
How do macrolides work
Inhibit protein synthesis by binding 50S subunit decreasing translocation a and tRNA release
26
Give two examples of macrolides
Clarithromycin | Erythromycin
27
How does fusidic acid work
Inhibits protein synthesis by binding to EF-G ribosome complex and preventing translocation of tRNA from A to P site
28
How do cycloserine and bacitracin work?
They work by affecting cell wall synthesis
29
Where does daptomtcin (cubicin) exert its effects as an antimicrobial
Cell membrane
30
Lincosamides and streptogramins act where?
Protein synthesis
31
Sulphonamides, trimethoprim and rifamycin all effect what?
NUcleic acid
32
Define antimicrobial
Chemicals which kill or inhibit microbial growth
33
What's intrinsic antimicrobial resistance and give an example
Innate properties of bacterial cell E.g cell wall
34
Give three mechanisms by which microbial resistance can occur
Inactivate/modify drug Alter drug target site Alter drug uptake/exit
35
Where are the beta lactamases in gram negative bacteria?
In the periplasmic space (still excreted out but accumulates)
36
In gram positive bacteria where are beta lactamases
They're released out into medium (need dense bacterial population)
37
Name two limited spectrum beta lactamases in E.coli and which one is most common
TEM-1 (most common) | TEM-2
38
Name two extended spectrum beta lactamases
CTX-M (e.coli & S.thyphimurium) NDM-1 (e.coli) resistant to all beta lactam drugs
39
Name three beta lactamase inhibitors
Clavulanic acid Sulbactam Tazobactam
40
Methicillin resistance in S.aureus is because of what?
Altered target site: | PBP2 --> PBP2a
41
What is resistance in haemophilus influenzae due to?
Altered target site: | PBP3--> PBP3a and 3b
42
What is resistance in streptococcus pneumoniae due to?
Altered target site: PBP1--> PBP1a & b PBP2--> PBP2a
43
Altered uptake can also be a cause of resistance to beta lactam drugs .. But in what type of bacteria and how?
GRAM -ve YO | reduced no./size of porins
44
How does bacteria become resistant to vancomycin
Changes in terminal amino acids of peptide chain: | D-Ala-D-Ala---> D-Ala-D-lactate (vancomycin can't bind/binds weakly)
45
How can you get resistance to aminoglycosides?
Inactivating enzymes Acetylase Adenylylase Phosphorylase
46
What antibiotics are effected by efflux pumps?
Tetracyclines | Quinolones
47
What does the R group of penicillins determine
``` Selectivity Solubility Stability Bioavailability B-lactamase resistance ```
48
What are the 4 classifications of penicillins
1) b-lactamase sensitive 2) b-lactamase resistant 3) broad spectrum 4) anti-pseudomonal
49
Give three examples of bacteria that cause meningitis
Neisseria meningitidis Strept pneumoniae Haemophilus influenzae
50
Name two first generation cephalosporins
Cefazolin | Cefradine
51
Name two second generation cephalosporins
Cefuroxime | Cefaclor
52
Name two third generation cephalosporins
Cefotaxime | Ceftriaxone
53
Name two fourth generation cephalosporins
Cefepime | Cefpirome
54
Carbapenems inhibit what
Cell wall synthesis
55
Give three examples of carbapenems
Imipenem Meropenem Doriopenem
56
What's the only monobactam used clinically
Aztreonam
57
Name four classes of beta-lactams
Penicillins Cephalosporins Carbapenems Monobactam
58
Name the Bacteria that causes tuberculosis
Mycobacterium tuberculosis
59
Why type and shape of bacteria causes tuberculosis
Slowing growing rod bacillus- acid fast bacteria
60
What does acid fast bacteria mean?
Doesn't show in gram stain due to rich lipid layer of fatty acids
61
Describe the four stages of TB
1) phagocytose by macrophages but they don't destroy 2) TB multiplies in macrophage for 7-21 days and bursts, incoming macrophages phagocytose released TB, release cytokines 3) cell mediated response initiated tubercules formed 4) bacteria multiply inside macrophage uncontrolled lysis, enzymes destroy local tissue
62
Name two ways you can diagnose active TB
Chest X-Ray | Sputum test
63
Name two ways you can diagnose latent TB
Tuberculin skin test | Molecular assays
64
When do you need to be screened for TB
If travelling to UK from country where TB is common if wishing to stay in UK for >6 months
65
Name four first line anti-TB drugs
Rifampicin Isoniazid Pyrazinamide Ethambutol
66
The anti TB drugs isoniazid and ethambutol exert their effects where?
Cell wall synthesis
67
Where does the anti-TB drug pyrazinamide exert its effects
Disrupts plasma membrane, increased permeability
68
In TB where does the anti TB drug rifampicin exert its effects?
Inhibits RNA synthesis
69
Streptomycin is the only aminoglycoside that can do what?
Get inside cells (second line for TB)
70
Name 5 second line anti TB drugs
``` Streptomycin Capreomycin Cycloserine Ciprofloxacin Azithromycin ```

Infection&immunity (9 decks)

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