Antibiotics and Resistance - Part 2

Question 1

Name the first streptogramin antibiotic to be released

Answer 1

Synercid

Question 2

Describe the structure of the first streptogramin antibiotic synercid

Answer 2

A combination of two cyclic peptides - quinupristin and dalforpristin

Question 3

Streptogramin antibiotics are distantly related to which antibiotic group?

Answer 3

The macrolides

Question 4

How do streptogramin antibiotics such as Synercid act?

Answer 4

They block protein synthesis by attaching to the 50S portion of the ribosome

Question 5

Against which bacteria are streptogramins effective against?

Answer 5

A broad range of gram-positive bacteria

Question 6

The oxazolidinones are a new class of antibiotics developed in response to…

Answer 6

Vancomycin resistance

Question 7

How do oxazolidinones act?

Answer 7

They act on the ribosome, inhibiting protein synthesis

Question 8

What is different in the way oxazolidinones act on the 50S ribosome compared to other antibiotics discussed?

Answer 8

They act close to the point where it interfaces with the 30S subunit

Question 9

The oxazolidinones are totally synthetic which may

Answer 9

make resistance slower to develop

Question 10

Give an example of an oxazolidinone and its function

Answer 10

Linezolid - used mainly to combat MRSA

Question 11

What is the mode of action of pleuromutilin antibiotics?

Answer 11

Interfere with protein synthesis

Question 12

What is the first pleuromutilin antibiotic to be approved?

Answer 12

Retapamulin

Question 13

What is a limitation of Retapamulin which is a pleuromutilin antibiotic?

Answer 13

It is limited to topical use

Question 14

What is pleuromutilin effective against?

Answer 14

Gram positive bacteria including MRSA

Question 15

A new class of antibiotics developed in recent years…

Answer 15

Lipopeptides

Question 16

Give an example of a lipopeptide that is effective against gram positive bacteria including MRSA infections

Answer 16

Daptomycin

Question 17

Daptomycin is produced by a…

Answer 17

Streptomycete

Question 18

Daptomycin is approved for what?

Answer 18

For certain skin infections

Question 19

What is the apparent mechanism of daptomycin which is a lipopeptide antibiotic

Answer 19

To attack the membrane of the bacterial cell

Question 20

Give an example of a lipopeptide antibiotic which is used for gram negative bacteria

Answer 20

Polymyxin B

Question 21

Infections caused by Pseudomonas Bacteria can be treated with

Answer 21

Polymyxin B which is a lipopeptide

By attacking the membrane of the bacterial cell

Question 22

Give an example of a rifamycin antibiotic

Answer 22

Rifampin

Question 23

How do the rifamycin class of antibiotics such as rifampin work?

Answer 23

They are nucleic acid synthesis inhibitors - work by inhibiting the synthesis of mRNA

Question 24

Rifampin are structurally related to…

Answer 24

The macrolides

Question 25

What is a valuable characteristic of rifampin?

Answer 25

The ability to penetrate and reach therapeutic levels in cerebrospinal fluid and abscesses

Question 26

What is the most important use of rifampin?

Answer 26

Against mycobacteria in the treatment of tuberculosis and leprosy

Question 27

What is the method of action of the quinolones and fluoroquinolones?

Answer 27

Nucleic acid synthesis inhibitors - inhibits an enzyme needed for the replication of DNA DNA gyrase

Question 28

The first quinolone group of antimicrobials is

Answer 28

Nalidixic acid

Question 29

Nalidixic acid has a limited use, explain.

Answer 29

Only application is for urinary tract infections

Question 30

Why were the quinolones of use?

Answer 30

Allowed the development of the synthetic quinolones known as the fluoroquinolones

Question 31

When were the fluoroquinolones developed from the quinolones?

Answer 31

In the 1980's

Question 32

Fluoroquinolones have a ______ spectrum of activity compared to quinolones

Answer 32

Broader

Question 33

Name two of the earliest generation fluoroquinolones

Answer 33

Norfloxacin and ciproflaxacin

Question 34

Name two of the newer groups of fluoroquinolones

Answer 34

Gemifloxacin and moxifloxacin

Question 35

What is a major issue with fluoroquinolones?

Answer 35

Resistance can develop rapidly, even during the course of a treatment

Question 36

Give an example of a group of antimicrobials which kill by the competitive inhibition of essential metabolites

Answer 36

Sulfonamides

Question 37

Why is folic acid important in microbes?

Answer 37

Folic acid is an important co enzyme needed for the synthesis of proteins, DNA and RNA

Question 38

How do sulfonamides act?

Answer 38

They are structurally similar to the folic acid precursor called para-aminobenzoic acid (PABA) Competitively bind with the enzyme meant for PABA Block folic acid production

Question 39

Give an example of drug-synergism

Answer 39

TMP-SMZ = trimethoprim and sulfamethoxazole

Question 40

What is drug synergism ?

Answer 40

Drug synergy occurs when drugs can interact in ways that enhance or magnify one or more effects

Question 41

The TMP-SMZ combination has what advantage?

Answer 41

Broader spectrum of activity and reduces the emergence of resistant strains

Question 42

How do most antifungal drugs work?

Answer 42

By targeting the sterols in the plasma membrane

Question 43

In fungal membranes, the principle sterol is?

Answer 43

Ergosterol

Question 44

In human membranes, the principle sterol is?

Answer 44

Cholestrol

Question 45

How does inhibition of ergosterol biosynthesis of fungal cells cause death?

Answer 45

The membranes become excessively permeable

Question 46

Name the most commonly used member of the antifungal polyene group.

Answer 46

Amphotericin B

Question 47

What is amphotericin B used for?

Answer 47

Fungal diseases - histoplasmosis, coccididomycosis and blastomycosis

Question 48

Azoles are widely used anti____ drugs

Answer 48

antifungal

Question 49

What were the first azoles?

Answer 49

The imidazoles

Question 50

Give two examples of the imidazoles

Answer 50

Clotrimazole and miconazole

Question 51

Azoles can be used without prescription for

Answer 51

topical application such as athlete's foot

Question 52

What is an advantage of triazole as an antifungal?

Answer 52

It is less toxic, and more water soluble

Question 53

The low toxicity and water solubility of triazole means that it is

Answer 53

more effective against systemic infections

Question 54

What are systemic infections?

Answer 54

Infections that affect the entire body

Question 55

Give two examples of triazoles

Answer 55

Fluconazole and itraconazole

Question 56

The allylamines work by...

Answer 56

Inhibiting the biosynthesis of ergosterols

Question 57

Give two examples of allylamines

Answer 57

Terbinafine and naftifine

Question 58

Other than the plasma membrane of fungal cells, what is another primary target for antifungal agents?

Answer 58

The beta-glucan of the cell wall

Question 59

What type of antifungals inhibit the biosynthesis of glucans?

Answer 59

The echinocandins

Question 60

The echinocandins inhibit the biosynthesis of glucans, what does this result in?

Answer 60

An incomplete cell wall which then results in cell lysis

Question 61

Other than targeting the fungal cell membrane or the fungal cell wall, what else can be target by antifungals?

Answer 61

Inhibition of nucleic acids

Question 62

Give an example of an antifungal which interferes with the biosynthesis of RNA and therefore disrupts protein synthesis

Answer 62

Flucytosine