Antibiotics Flashcards

1
Q

Antibiotics

A

chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Another name for antibiotics:

A

“magic bullet”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

An antimicrobial drug has _________ __________ if it kills microbial cells, but does not kill host cells.

A

selective toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

–cidal

A

kills microbes directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

–static

A

prevents microbes from growing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

broad spectrum

A

effective against wide range of species, including both gram negative and gram positive species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

example of a broad spectrum antibiotic

A

tetracycline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

narrow spectrum

A

only active against select species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

example of a narrow spectrum antibiotic

A

penicillin G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are gram negative more resistant?

A

outer membrane of gram negative species inhibits the passage of many antiobiotics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Superinfection

A

Ab tx, especially broad-spectrum, may destroy normal flora

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens in times of superinfection?

A

Ab resistant microbes (Candida albicans) can grow unchecked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

4 Mechanisms of Action Ab’s use

A
  1. Inhibition of cell wall synthesis
  2. Inhibition of protein synthesis
  3. Inhibition of nucleic acid replication and transcription
  4. Inhibition of essential metabolite synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Natural penicillin

A

Narrow spectrum of range; susceptible to penicillinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What type of bacteria is penicillin effective against and why?

A

gram (+) - interferes with cross-linking of peptidoglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Semi-synthetic penicillin

A

extended spectrum and/or resistance to penicillinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Penicillinase

A

a beta-lactamase enzyme effective against penicillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does penicillinase work?

A

cleaves beta-lactam ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

4 features of Colistin

A
  1. disrupts outer membrane of gram negative cell wall
  2. disrupts plasma membrane
  3. cell lysis
  4. last resort due to nephrotoxicity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

2 Mycobacterium species

A

leprosy and TB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Isoniazid

A

inhibits mycolic acid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

ethambutol

A

inhibits corporation of mycolic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

3 things that inhibit replication?

A

ciproflaxin, nalidixic acid, UTIs

24
Q

What does Rifamycin do?

A

inhibit transcription by selectively binding to the bacterial RNA polymerase

25
chloramphenicol
binds to 50S portion and inhibits formation of peptide bond
26
streptomycin
changes shape of 30S portion causing code on mRNA to be read incorrectly
27
tetracycline
interfere with attachment of tRNA to mRNA-ribosome complex?
28
Chloramphenicol, Streptomycin, and Tetracycline inhibit what?
Protein synthesis
29
An inhibitor of metabolic enzymes
sulfonamides
30
Sulfonamides are ________ inhibitors. They inhibit ____ ____ _____. They are a ________ _________ antibiotic.
competitive; folic acid synthesis; broad spectrum
31
Erythromycin inhibits translation. Why does erythromycin have a spectrum of activity limited largely to gram positive bacteria?
The gram-negative cell wall blocks erythromycin.
32
Primary sterol in fungal membranes
ergosterol
33
primary sterol in animal membranes
cholesterol
34
Examples of antifungals that target ergosterol synthesis:
Azoles like miconazole and triazole
35
Flucytosine
cytosine analog interferes with RNA synthesis
36
Griseofulvin
inhibits microtubule formation
37
MIC
minimal inhibitory concentration
38
MBC
minimal bactericidal concentration
39
2 ways to measure susceptibility of drug:
Disk Diffusion Method (Kirby-Bauer Test) & Broth dilution
40
Synergism
occurs when the effect of two drugs together is greater than the effect of either alone
41
Antagonism
occurs when the effect of two drugs together is less than the effect of either alone
42
4 Mechanisms of Ab Resistance
1. blocking entry 2. inactivation by enzymes 3. alteration of target molecules 4. efflux of antibiotic
43
MDR Pump
Multi-drug resistance; can export many kinds of Abs
44
Amphotericin B
binds to ergosterol and forms pores in membrane; cytotoxic, generally used only for severe systemic infections
45
2 ways in which bacteria acquire Ab resistane?
1. Mutation during DNA replication | 2. Horizontal transfer
46
Horizontal Transfer
resistance genes are often on plasmids or transposons that can be transferred between bacteria
47
Problems with Antivirals
Difficult to find because there are few targets you can use (selective toxicity issues)
48
Amantadine
inhibits viral uncoating (preventing entry of virus into host cell)
49
Zanamavir
blocks neurominidase (the spikes on the outside of viruses; this prevents them from being released)
50
Acyclovir
analog of guanosine that has no 3' OH. The chain terminates thus blocking DNA synthesis (including yours)
51
Ribavirin
Lowers fidelity of RNA polymerase,
52
AZT (azidothymidine)
nucleoside analog reverse transcriptase inhibitor
53
interferons
normal host proteins that prevent spread of viruses to new cells
54
alpha interferon
used to tread viral hepatitis
55
imiquimod
promotes interferon production