Antibiotics

Question 1

Antibiotic modes of action (3)

Answer 1

1. Bacteriostatic
2. Bacteriocidal
3. Bacteriolytic

Question 2

Bacteriostatic

Answer 2

Total cell count and viable cell count remain the same

Question 3

Bacteriocidal

Answer 3

Total cell count remains the same but viable cell count decreases

Question 4

Bacteriolytic

Answer 4

Total cell count and viable cell count both decrease

Question 5

Cell wall synthesis ABs

Answer 5

Cycloserine
Penicillin
Carbapenems
Cephalosporins
Bacitracin
Vancomycin
Monobactams

Question 6

Folic acid ABs

Answer 6

Trimethoprim

Sulfonamides

Question 7

Cytoplasmic membrane structure ABs

Answer 7

Polymyxins

Daptomycin

Question 8

Lipid biosynthesis ABs

Answer 8

Plantensymicin

Question 9

Protein synthesis ABs (tRNA)

Answer 9

Mupirocin

Puromycin

Question 10

30S inhibitors ABs

Answer 10

Tetracyclines
Spectinomycin
Streptomycin
Gentamycin
Kanamycin
Amikacin
Nitrofurans

Question 11

50S inhibitors ABs

Answer 11

Erythromycin (macrolides)
Chloramphenicol
Clindamycin
Lincomycin

Question 12

RNA polymerase ABs

Answer 12

Rifampin

Streptovaricins

Question 13

RNA elongation ABs

Answer 13

Actinomycin

Question 14

DNA gyrase ABs

Answer 14

Quinolones: Nalidixic acid, Ciprofloxacin, Novobiocin

Question 15

Macrolide structure

Answer 15

12-16 membered macrolactone ring with various amino sugars

Question 16

What do macrolides do

Answer 16

Inhibit the 50S subunit of the ribosome

Question 17

In the 50s subunit

Answer 17

Macrolides bind to a specific site in the upper part of the peptide exit tunnel

Question 18

What effect does macrolide binding have

Answer 18

Inhibition of translation (peptides can’t exit tunnel)

Question 19

What do fluoroquinolones do

Answer 19

Target DNA gyrase

Question 20

Which kinds of DNA gyrase do fluoroquinolones target

Answer 20

Topoisomerase II and IV

Question 21

Fluoroquinolones are particularly effective against

Answer 21

Gram positive bacteria

Question 22

Fluoroquinolones enter Gram negative bacteria through

Answer 22

Outer membrane porins

Question 23

Fluoroquinolones enter Gram positive bacteria by

Answer 23

Passive diffusion

Question 24

Newer fluoroquinolones have a

Answer 24

Broader spectrum and better activity against Gram positive

Question 25

Fluoroquinolones are the

Answer 25

Second most used antibiotic

Question 26

A synthetic antimicrobial

Answer 26

Fluoroquinolones

Question 27

Fluoroquinones include

Answer 27

Nalidixic acid Ciprofloxacin Novobiocin

Question 28

Cephalosporins are

Answer 28

Semi synthetic beta lactam antibiotics related to penicillin

Question 29

Cephalosporins are derived from

Answer 29

Cephalosporium (fungus)

Question 30

Beta lactam antibiotics interfere with

Answer 30

Bacterial cell wall synthesis

Question 31

Peptidoglycan is made up of

Answer 31

alternating residues of β-(1,4) linked N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

Question 32

Beta lactam antibiotics bind to

Answer 32

Transpeptidase enzymes that normally catalyze linkage of the glycan chains (where new tetrapeptides have been inserted) Binding stops this activity

Question 33

New ABs inhibit

Answer 33

``` a broad range of targets including: topoisomerase protein synthesis cell membranes cell wall ```

Question 34

Beta lactamase inhibitors

Answer 34

Overcome inactivation of beta lactam antibiotics

Question 35

Phage are

Answer 35

Natural antimicrobials

Question 36

Stages of phage infection (5)

Answer 36

1. Adsorption to a specific receptor 2. DNA injection 3. Redirection of host metabolism to phage replication 4. Assembly and packing of phage particles 5. Bacterial cell lysis and progeny release

Question 37

Phage attachment is

Answer 37

Highly specific

Question 38

Peptidoglycan and pore formation by lytic phage allows

Answer 38

Phage DNA injection

Question 39

Phage late proteins include

Answer 39

Lysins, Holins, Murein synthesis inhibitors

Question 40

Phage late proteins are responsible for

Answer 40

Host cell lysis

Question 41

Lytic phage advantages

Answer 41

Cheap | Specific

Question 42

Lytic phage disadvantages

Answer 42

Narrow spectrum | Rapid resistance

Question 43

Alternative phage strategies use

Answer 43

Phage to deliver a protein that interferes with an essential bacterial process

Question 44

Alternative phage strategies cause

Answer 44

Bacterial to be more susceptible to ABs

Question 45

Phage therapy can be combined with

Answer 45

CRISPR

Question 46

Anti Virulence Strategies

Answer 46

Inhibit specific mechanisms that promote infection

Question 47

Anti virulence strategies offer

Answer 47

Reduced selection pressure for drug resistant mutation

Question 48

Virulence specific drugs are good because

Answer 48

They do not cause the dramatic alteration in host microbiota that ABs do

Question 49

UPEC

Answer 49

Uro pathogenic E.coli

Question 50

Mechanism of UPEC infection (5)

Answer 50

1. Binding to Facet cells 2. Invasion and replication in cells 3. Biofilm formation (IBC) 4. Biomass dispersion and cell exit 5. Spread of infection

Question 51

IBC

Answer 51

Intracellular bacterial community

Question 52

UPEC in anti virulence strategies (2)

Answer 52

1. Pilicides Pilus binds to uroplakin on facet cells - no pili=no binding 2. Creation of analogs to interrupt mediation of binding to the natural receptor

Question 53

Quorum sensing

Answer 53

Bacterial communication

Question 54

Quorum sensing controls

Answer 54

A range of phenotypes including virulence factors

Question 55

Inhibiting quorum sensing with a reporter upstream of a quorum sensing gene

Answer 55

Can result in virulence genes being switched off

Question 56

Reporter genes can be used to monitor

Answer 56

The levels of expression of another gene

Question 57

Targeting toxin production in anti virulence strategies

Answer 57

Toxin production is tightly regulated | Virstatin inhibits transcription of cholera toxin

Question 58

Virstatin

Answer 58

Allows targeting of a specific operon that produces cholera toxin

Question 59

Receptor mimics in anti virulence strategies

Answer 59

Mop up the toxin, stronger affinity so no binding to host receptor

Question 60

Protein secretion systems in anti virulence

Answer 60

Bacteria need to get proteins to the cell wall Molecular needles that inject effector molecules into host cell membranes Very specific host cell pathogens Knocking out secretion systems reduce virulence

Question 61

Faecal extracts inhibit the invasiveness of

Answer 61

Salmonella

Question 62

The human gut metabolome

Answer 62

Has anti virulence activity

Question 63

Type III secretion systems produce

Answer 63

Effectors that cause disease (actin rearrangment etc)

Question 64

Synergistic drug usage causes problems because

Answer 64

Killing off susceptible bacteria removes competition and allows multi drug resistant bacteria to proliferate