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Microbiology > Antibiotics and Resistance - Part 2 > Flashcards

Antibiotics and Resistance - Part 2 Flashcards

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Biology 101 flashcards
1
Q

Name the first streptogramin antibiotic to be released

A

Synercid

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2
Q

Describe the structure of the first streptogramin antibiotic synercid

A

A combination of two cyclic peptides - quinupristin and dalforpristin

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3
Q

Streptogramin antibiotics are distantly related to which antibiotic group?

A

The macrolides

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4
Q

How do streptogramin antibiotics such as Synercid act?

A

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

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5
Q

Against which bacteria are streptogramins effective against?

A

A broad range of gram-positive bacteria

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6
Q

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

A

Vancomycin resistance

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7
Q

How do oxazolidinones act?

A

They act on the ribosome, inhibiting protein synthesis

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8
Q

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

A

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

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9
Q

The oxazolidinones are totally synthetic which may

A

make resistance slower to develop

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10
Q

Give an example of an oxazolidinone and its function

A

Linezolid - used mainly to combat MRSA

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11
Q

What is the mode of action of pleuromutilin antibiotics?

A

Interfere with protein synthesis

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12
Q

What is the first pleuromutilin antibiotic to be approved?

A

Retapamulin

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13
Q

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

A

It is limited to topical use

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14
Q

What is pleuromutilin effective against?

A

Gram positive bacteria including MRSA

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15
Q

A new class of antibiotics developed in recent years…

A

Lipopeptides

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16
Q

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

A

Daptomycin

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17
Q

Daptomycin is produced by a…

A

Streptomycete

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18
Q

Daptomycin is approved for what?

A

For certain skin infections

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19
Q

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

A

To attack the membrane of the bacterial cell

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20
Q

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

A

Polymyxin B

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21
Q

Infections caused by Pseudomonas Bacteria can be treated with

A

Polymyxin B which is a lipopeptide

By attacking the membrane of the bacterial cell

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22
Q

Give an example of a rifamycin antibiotic

A

Rifampin

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23
Q

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

A

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

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24
Q

Rifampin are structurally related to…

A

The macrolides

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25
Q

What is a valuable characteristic of rifampin?

A

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

26
Q

What is the most important use of rifampin?

A

Against mycobacteria in the treatment of tuberculosis and leprosy

27
Q

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

A

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

28
Q

The first quinolone group of antimicrobials is

A

Nalidixic acid

29
Q

Nalidixic acid has a limited use, explain.

A

Only application is for urinary tract infections

30
Q

Why were the quinolones of use?

A

Allowed the development of the synthetic quinolones known as the fluoroquinolones

31
Q

When were the fluoroquinolones developed from the quinolones?

A

In the 1980’s

32
Q

Fluoroquinolones have a ______ spectrum of activity compared to quinolones

A

Broader

33
Q

Name two of the earliest generation fluoroquinolones

A

Norfloxacin and ciproflaxacin

34
Q

Name two of the newer groups of fluoroquinolones

A

Gemifloxacin and moxifloxacin

35
Q

What is a major issue with fluoroquinolones?

A

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

36
Q

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

A

Sulfonamides

37
Q

Why is folic acid important in microbes?

A

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

38
Q

How do sulfonamides act?

A

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

39
Q

Give an example of drug-synergism

A

TMP-SMZ = trimethoprim and sulfamethoxazole

40
Q

What is drug synergism ?

A

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

41
Q

The TMP-SMZ combination has what advantage?

A

Broader spectrum of activity and reduces the emergence of resistant strains

42
Q

How do most antifungal drugs work?

A

By targeting the sterols in the plasma membrane

43
Q

In fungal membranes, the principle sterol is?

A

Ergosterol

44
Q

In human membranes, the principle sterol is?

A

Cholestrol

45
Q

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

A

The membranes become excessively permeable

46
Q

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

A

Amphotericin B

47
Q

What is amphotericin B used for?

A

Fungal diseases - histoplasmosis, coccididomycosis and blastomycosis

48
Q

Azoles are widely used anti____ drugs

A

antifungal

49
Q

What were the first azoles?

A

The imidazoles

50
Q

Give two examples of the imidazoles

A

Clotrimazole and miconazole

51
Q

Azoles can be used without prescription for

A

topical application such as athlete’s foot

52
Q

What is an advantage of triazole as an antifungal?

A

It is less toxic, and more water soluble

53
Q

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

A

more effective against systemic infections

54
Q

What are systemic infections?

A

Infections that affect the entire body

55
Q

Give two examples of triazoles

A

Fluconazole and itraconazole

56
Q

The allylamines work by…

A

Inhibiting the biosynthesis of ergosterols

57
Q

Give two examples of allylamines

A

Terbinafine and naftifine

58
Q

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

A

The beta-glucan of the cell wall

59
Q

What type of antifungals inhibit the biosynthesis of glucans?

A

The echinocandins

60
Q

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

A

An incomplete cell wall which then results in cell lysis

61
Q

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

A

Inhibition of nucleic acids

62
Q

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

A

Flucytosine

Microbiology (18 decks)

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