Flashcards in Antibiotics and Resistance - Part 2 Deck (62):
1
Name the first streptogramin antibiotic to be released
Synercid
2
Describe the structure of the first streptogramin antibiotic synercid
A combination of two cyclic peptides - quinupristin and dalforpristin
3
Streptogramin antibiotics are distantly related to which antibiotic group?
The macrolides
4
How do streptogramin antibiotics such as Synercid act?
They block protein synthesis by attaching to the 50S portion of the ribosome
5
Against which bacteria are streptogramins effective against?
A broad range of gram-positive bacteria
6
The oxazolidinones are a new class of antibiotics developed in response to...
Vancomycin resistance
7
How do oxazolidinones act?
They act on the ribosome, inhibiting protein synthesis
8
What is different in the way oxazolidinones act on the 50S ribosome compared to other antibiotics discussed?
They act close to the point where it interfaces with the 30S subunit
9
The oxazolidinones are totally synthetic which may
make resistance slower to develop
10
Give an example of an oxazolidinone and its function
Linezolid - used mainly to combat MRSA
11
What is the mode of action of pleuromutilin antibiotics?
Interfere with protein synthesis
12
What is the first pleuromutilin antibiotic to be approved?
Retapamulin
13
What is a limitation of Retapamulin which is a pleuromutilin antibiotic?
It is limited to topical use
14
What is pleuromutilin effective against?
Gram positive bacteria including MRSA
15
A new class of antibiotics developed in recent years...
Lipopeptides
16
Give an example of a lipopeptide that is effective against gram positive bacteria including MRSA infections
Daptomycin
17
Daptomycin is produced by a...
Streptomycete
18
Daptomycin is approved for what?
For certain skin infections
19
What is the apparent mechanism of daptomycin which is a lipopeptide antibiotic
To attack the membrane of the bacterial cell
20
Give an example of a lipopeptide antibiotic which is used for gram negative bacteria
Polymyxin B
21
Infections caused by Pseudomonas Bacteria can be treated with
Polymyxin B which is a lipopeptide
By attacking the membrane of the bacterial cell
22
Give an example of a rifamycin antibiotic
Rifampin
23
How do the rifamycin class of antibiotics such as rifampin work?
They are nucleic acid synthesis inhibitors - work by inhibiting the synthesis of mRNA
24
Rifampin are structurally related to...
The macrolides
25
What is a valuable characteristic of rifampin?
The ability to penetrate and reach therapeutic levels in cerebrospinal fluid and abscesses
26
What is the most important use of rifampin?
Against mycobacteria in the treatment of tuberculosis and leprosy
27
What is the method of action of the quinolones and fluoroquinolones?
Nucleic acid synthesis inhibitors - inhibits an enzyme needed for the replication of DNA
DNA gyrase
28
The first quinolone group of antimicrobials is
Nalidixic acid
29
Nalidixic acid has a limited use, explain.
Only application is for urinary tract infections
30
Why were the quinolones of use?
Allowed the development of the synthetic quinolones known as the fluoroquinolones
31
When were the fluoroquinolones developed from the quinolones?
In the 1980's
32
Fluoroquinolones have a ______ spectrum of activity compared to quinolones
Broader
33
Name two of the earliest generation fluoroquinolones
Norfloxacin and ciproflaxacin
34
Name two of the newer groups of fluoroquinolones
Gemifloxacin and moxifloxacin
35
What is a major issue with fluoroquinolones?
Resistance can develop rapidly, even during the course of a treatment
36
Give an example of a group of antimicrobials which kill by the competitive inhibition of essential metabolites
Sulfonamides
37
Why is folic acid important in microbes?
Folic acid is an important co enzyme needed for the synthesis of proteins, DNA and RNA
38
How do sulfonamides act?
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
Give an example of drug-synergism
TMP-SMZ = trimethoprim and sulfamethoxazole
40
What is drug synergism ?
Drug synergy occurs when drugs can interact in ways that enhance or magnify one or more effects
41
The TMP-SMZ combination has what advantage?
Broader spectrum of activity and reduces the emergence of resistant strains
42
How do most antifungal drugs work?
By targeting the sterols in the plasma membrane
43
In fungal membranes, the principle sterol is?
Ergosterol
44
In human membranes, the principle sterol is?
Cholestrol
45
How does inhibition of ergosterol biosynthesis of fungal cells cause death?
The membranes become excessively permeable
46
Name the most commonly used member of the antifungal polyene group.
Amphotericin B
47
What is amphotericin B used for?
Fungal diseases - histoplasmosis, coccididomycosis and blastomycosis
48
Azoles are widely used anti____ drugs
antifungal
49
What were the first azoles?
The imidazoles
50
Give two examples of the imidazoles
Clotrimazole and miconazole
51
Azoles can be used without prescription for
topical application such as athlete's foot
52
What is an advantage of triazole as an antifungal?
It is less toxic, and more water soluble
53
The low toxicity and water solubility of triazole means that it is
more effective against systemic infections
54
What are systemic infections?
Infections that affect the entire body
55
Give two examples of triazoles
Fluconazole and itraconazole
56
The allylamines work by...
Inhibiting the biosynthesis of ergosterols
57
Give two examples of allylamines
Terbinafine and naftifine
58
Other than the plasma membrane of fungal cells, what is another primary target for antifungal agents?
The beta-glucan of the cell wall
59
What type of antifungals inhibit the biosynthesis of glucans?
The echinocandins
60
The echinocandins inhibit the biosynthesis of glucans, what does this result in?
An incomplete cell wall which then results in cell lysis
61
Other than targeting the fungal cell membrane or the fungal cell wall, what else can be target by antifungals?
Inhibition of nucleic acids
62