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Microbiology > Ch. 12: Drugs, Microbes, Host- Elements of Chemotherapy > Flashcards

Ch. 12: Drugs, Microbes, Host- Elements of Chemotherapy Flashcards

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1
Q

Chemotherapy

A

any chemical used to treat/prevent disease

set of chemical substances/drugs to treat/prevent disease

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2
Q

Prophylaxis

A

use of a drug to prevent potential for future infection in a person at risk

ex) condom

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3
Q

Antibiotics

A

substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms

~kill microbial infections in a host

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4
Q

Analog

A

[chemistry] a compound that closely resembles another in structure

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5
Q

Protease

A

an enzyme which breaks down proteins and peptides.

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6
Q

Resistance (R) factors

A

plasmids, typically shared among bacteria by conjugation, that provide resistance to the effects of antibiotics

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7
Q

Beta-lactamase

A

an enzyme secreted by certain bacteria that cleaves the beta-lactam ring of penicillin and cephalosporin, and thus provides for resistance against the antibiotic

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8
Q

MDR bacteria

A

Multidrug resistant (MDR) — acquired nonsusceptibility to at least one agent in three or more antimicrobial categories.

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9
Q

Antibiogram

A

test that analyzes the effectiveness of a specific antibiotic on a disease that a patient has

ex) Kirby-Bauer test/ E test/ tube dilution for antibiotic sensitivity

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10
Q

Superinfection

A

infection caused by microbe resistant to antibiotics; commonly formed as a secondary infection

(candida, yeast infections, c. difficile).

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11
Q

What are the four organisms from which most of our antibiotics are derived?

A

Penicillium
Streptomyces

Bacillus spp
cephalosporium

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12
Q

most antibiotics are produced by:

A

bacteria & fungi

[not viruses]

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13
Q

Alexander Fleming

A

discovered first real [naturally derived] antibiotic in 1928

[penicillin]

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14
Q

draw the beta-lactam ring

A
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15
Q

beta-lactam antiobiotics act by:

A

blocking cell wall synthesis

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16
Q

Polymyxins act by:

A

creating holes in bacterial cell membranes

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17
Q

Substances that are naturally produced by certain microorganisms that can inhibit or destroy other microorganisms are called

A

antibiotics.

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18
Q

Antibiotics effective against a wide variety of microbial types are termed

A

broad-spectrum.

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19
Q

Antimicrobics effective against only gram-positive bacteria would be termed

A

narrow-spectrum drugs.

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20
Q

Penicillins and cephalosporins MOA is:

A

block cross-linking of peptidoglycan.

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21
Q

Which of the following is LEAST likely to cause allergies?

penicillin
vancomycin
sulfonamides

A

vancomycin

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22
Q

Sulfonamides MOA:

A

block folic acid synthesis.

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23
Q

fluoroquinolones MOA is:

A

they work by inhibiting bacterial DNA replication.
[by targeting DNA gyrase]

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24
Q

Antibiotics that are ___________ include azithromycin and erythromycin.

A

macrolides

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25
Q

Ampicillin, amoxicillin, mezlocillin, and penicillin all have:

A

a beta-lactam ring.

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26
Q

Which of the following is the most toxic drug to humans?

ciprofloxacin.

chloramphenicol.

gentamicin.

cephotaxime.

A

chloramphenicol.

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27
Q

Species of __________ produce polymyxins.

A

Bacillus

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28
Q

There are fewer antifungal, antiprotozoan, and antihelminth drugs compared to antibacterial drugs because these organisms:

A

are so similar to human cells that selective drug toxicity is difficult to achieve.

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29
Q

Where is quinine derived from?

A

a tree

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30
Q

Antivirals that target reverse transcriptase would be used to treat

A

HIV

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31
Q

An antiviral that is a thymine analog would have an antiviral mode of action that

A

blocks DNA synthesis.

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32
Q

One of the greatest challenges in development of antivirals is finding drugs that are

A

selectively toxic for viruses.

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33
Q

The multidrug resistant pumps in many bacterial cell membranes cause

A

removal of drugs from the cell.

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34
Q

The ____________________ uses an agar surface, seeded with the test bacterium, to which small discs containing a specific concentration of several drugs are placed on the surface.

A

Kirby-Bauer test

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35
Q

Why has the United States and Europe banned the use of human drugs in animal feeds?

A

Because it contributes to the growing drug resistance problem.

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36
Q

Penicillinases do what?

A

destroy penicillin

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37
Q

A superinfection results from

A

decrease in most normal flora with overgrowth of an unaffected species.

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38
Q

Which antimicrobial is contraindicated for children due to permanent tooth discoloration?

A

tetracycline

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39
Q

Antibiotics are derived from all the following except

Cephalosporium.

Bacillus.

Streptomyces.

Staphylococcus.

Penicillium.

A

Staphylococcus.

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40
Q

Aminoglycosides MOA is:

A

attach to the 30S ribosomal subunit and disrupt protein synthesis.

41
Q

What are the 2 ways antihelminthic drugs work against the helminth?

A

1) Paralyze the worm in your intestine; worm is released from the intestinal lining and pooped out

2) block nutrient absorption by tapeworm causing it to starve to death or will release and leave in poop

42
Q

Acyclovir is used to treat :

A

genital herpes.

43
Q

What are the antibiotic resistance genes generally called?

A

R genes

44
Q

How long have antibiotics been around?

A

For millions to billions of years

45
Q

While trying to start an IV on a patient, Kurt received a needlestick injury and blood exposure involving a patient with AIDS. He was immediately started on three different antiretroviral medications. The advantage of using combined therapy in this circumstance is

A

this should prevent the emergence of drug-resistant microbes.

46
Q

Janice has just had hip replacement surgery and her physician has prescribed antibiotics and directed her to take them every time she has a dental appointment. This is an example of antibiotic

A

prophylaxis.

47
Q

Albert Alexander :

A

was the first patient to be treated with injections of penicillin [due to infection after rose thorn scratch; still died]

48
Q

Which genera produce the widest variety of antibiotics?

A

streptomyces [1/3 of all types of antibiotics today]

49
Q

Describe the ways in which antibiotics can destroy a microbe

A

-target cell wall [lysis] or cell membrane [leak/death]
-affect DNA/RNA = replication/mutations…
-protein production; targeting ribosomes
-metabolic pathway by inhibiting enzyme catalyzed reactions

50
Q

identify characteristics of the ideal antimicrobial drug

A
51
Q

Penicillin

[Structure, MOA]

A

*Structure: square beta-lactam ring; 5 atom house shape
*Anything that ends with -cillin

MOA: competitive inhibition of enzyme involved in cross-linking of peptidoglycan (blocks cell wall formation)

*Natural source- penicillium

*problems: higher than typical antibiotic resistance in human pathogens & allergies

52
Q

Cephalosporin

[Structure, MOA]

A

*Comes from ceopholosporium
*Starts with -ceph, -cef, -kef…

*Structure- 6 atoms- swimming pool shape
No real problems with use [less likely than others]

*MOA: Block cell wall synthesis of peptidoglycan by competitive inhibition of enzymes involved in cross-linking ; beta-lactam drug ; same MOA as penicillin

53
Q

Vancomycin

[MOA]

A

*narrow spectrum drug

*Semi-synthetic; comes from streptomyces

*MOA: targets cell wall; prevents cross-linking by causing cell wall to bind to itself
*Very selective; targets peptidoglycan

*Very toxic drug; administered slowly; if too quickly, can cause serious pain

54
Q

Polymyxins

[MOA]

A

*Semi-synthetic; Comes from Bacillus polymyxa [only one here from bacillus]; narrow-spectrum

*MOA: Targets bacterial cell membranes; acts as detergent; disrupts cell membrane & causes leaks

*Problem: toxic to kidney bc targets cell membranes [used for antibiotic-resistant UTIs etc..]

55
Q

Fluoroquinolones

[MOA]

A

*Usually ends in -floxacin [cipro-, moxi-, nor-…]
*Synthetic [artifically made]; broad-spectrum

*MOA: Target DNA replication by targeting [binding to] DNA gyrase, preventing cell divison

*Side effects may include brain seizures; generally not toxic though

56
Q

Aminoglycosides

[2 types, structure, MOA]

A

*Semi-synthetic, usually come from streptomyces or related species

MOA: interfere with protein synthesis [Target 30S ribosomal subunit]; Targets translation; more selectivity; inhibits initiation and translocation and leads to a misreading of mRNA.

2 types
Streptomycin - older [ a little toxic ; SE hearing loss]

Gentamicin - newer [ less toxic]

Streptomycin structure = 6 carbon ring + 2 amino sugars

57
Q

Tetracyclines

[structure, MOA]

A

*Broad spectrum

*structure = 4 circles connected to each other
*Come from streptomyces

*MOA: Target 30S ribosomal subunit; Attach to 30S subunit and blocks A site, preventing translation

*Side effects- aesthetic effect on teeth/gum line; also can interfere with fetal bone development; GI issues

58
Q

Chloramphenicol

[Structure, MOA]

A

*Look for Cl2 chlorine in structure

*Comes from streptomyces; broad-spectrum

*MOA: Binds to 50S subunit; prevents peptide bond formation [blocks ribozyme activity]

*Toxic to mitochondria [affects bone marrow, causes anemia]
*Not commonly used in hospitals but more for research; immediately halts protein synthesis

59
Q

Macrolides

[structure, MOA]

A

*Ex) erythromycin

*Comes from streptomyces

*Structure: like a lobster, 3 circles together and 2 other circles next to it

*MOA: Binds to 50S subunit; inhibits translocation

60
Q

Sulfonamides

[structure, MOA]

A

*Totally synthetic [Synthetic; came from dye]; broad-spectrum

*Structure: blue circle connected to 3 other possible shapes; find the aromatic ring and see if the sulfur group and amino group on another side

*MOA: competitive inhibition; targets folate metabolism [enzyme that synthesizes folate]; very selective

[Folate is used to make nucleotides]

*Major problem = allergies

61
Q

which 2 antibiotics are most commonly associated with allergies?

A

penicillin & sulfanomides

62
Q

Polyenes- antifungal

[Structure, MOA]

A

*Structure: 1 big circle structure
*Come from streptomyces

*MOA: Target fungal cell membranes; targets (binds to) ergosterols causing membrane leaks [doesn’t bind to cholesterol bc mostly selective]

63
Q

Azoles - antifungal

[MOA]

A

*Completely synthetic antifungal

*MOA: inhibit ergosterol synthesis

*More synthetic, less side effects then polyenes

64
Q

Chloroquine

[MOA, example]

A

-Anti-protozoal; selective

ex) Quinine: comes from cinchona tree bark

*Typical target is protozoa (specifically, malaria)

*MOA: Selectively accumulates in lysosomes of parasites; Parasites consume this, gets into their lysosome, this will change chemical structure which cross links to the parasite’s DNA [destroying its DNA]

*Downside: resistance is developing in plasmodium parasites

65
Q

Metronidazole

[MOA]

A

*Antiprotozoal used to treat amoebic infections (amoebic dysentery, giardia..); also an antibiotic

*Completely synthetic, artificial; highly selective

[[[Ends in Azole but different than Azoles]]]

*MOA: Causes DNA double-strand breakage [occurs when it is reduced in lysosome] [similar mechanism to quinine]

66
Q

Antihelminthic drugs

A

*kill tapeworms, nematodes…

*Remain and kill things in your intestine

*most common ones work in the intestine

*Work in 2 ways-
1. Paralyze the worm in your intestine; worm is released from the intestinal lining and pooped out
2. block nutrient absorption by tapeworm causing it to starve to death or will release and leave in poop

*Almost no side effects; work well

67
Q

Antiviral drugs

*know main drugs and the 3 MOA

A

Inhibiting viral adsorption

Inhibit the nucleic acid synthesis

Or inhibiting proper release

68
Q

Tamiflu & Relenza MOA

[anti-virals- MOA]

A

MOA: block proper budding/release from the host cell [useful early in flu infection];

*starting to see some resistance with Tamiflu

69
Q

Cyclovir

[Anti-viral- MOA]

A

treats cold sores by herpes virus

MOA: inhibits DNA replication

70
Q

AZT

[Anti-viral]

A

works for cells infected with HIV; works well

*MOA: selectively inhibiting HIV’s reverse transcriptase, the enzyme that the virus uses to make a DNA copy of its RNA.

71
Q

HAART

[Anti-viral]

A

*highly active anti retro viral therapy- multiple pill cocktail ; entails use of 3+ drugs that work in 2+ different ways

[could be like AZT, protease inhibitors, or can target HIV viral release/fusion/adhesion]

72
Q

Truvada

[AKA prep: post-exposure prophylaxis]

A

*Includes 2 different reverse transcriptase inhibitors

*eliminate the risk of HIV; prophylactic
*daily pill; usually used for people that don’t have HIV yet; prevent infections
*can also be used for post-exposure prophylaxis
~few side effects

73
Q

Interferons

[Anti-viral]

A

*last resort; naturally occurring molecules produced by the immune system when you have a viral infection
~attacks viruses and cancer
~Derived from human body/gene

*negative side effects- harder to fight off other types of infections

74
Q

How do bacteria acquire drug resistance?

[5 ways]

A
  1. Drug inactivation- R gene makes a protein that is an enzyme that destroys antibiotic (breaks covalent bonds) EX) penecillinase, betalactamase
  2. Decreasing cell permeability; R gene makes a protein that keeps antibiotic out
  3. Activation of drug pumps- R gene produces a protein that pumps antibiotic out of the cell using ATP [MDR multi drug resistant pumps]
  4. Change in drug binding site on target [binding site on target [ribosome] is altered, so drug has no effect]
  5. Use of alternative metabolic pathways
75
Q

What contributes to the rise in drug resistance in the population?

[3 categories]

A
  1. Use of antibiotics in hospital setting [inappropriate use like doctors prescribing antibiotics w/o proper diagnosis/ when cause is viral infection like a cold]
  2. Antibiotic use in animal feed
  3. World-wide drug use [antibiotic use around the world; overuse: antibiotics available without prescription; underuse: not fulfilling full antibiotic course]
76
Q

How can we limit the increase seen in drug resistance in bacteria?

A
  1. Drug usage
    -Accurate diagnosis and prescribing, using antiobiogram test
    -Make sure patients comply - finish antibiotics
    -Combined therapy 2+ drugs that enhance the effectiveness of single antibiotic
  2. Drug research
    -Developing shorter-term, higher dose antimicrobials that are cheaper, more effective, and less side effects
    -Seeking out new strategies like using bacteriophage therapy
  3. Long-term strategies
    -Education of healthcare workers/public
    -Only use antimicrobials when absolutely needed
    -vaccination
    -stop adding antibiotics to animal feed
77
Q

How can antibiotics harm the person taking them?

A

1/20 ppl that take antibiotics can have an adverse effect

*Direct damage to human tissue [usually kidney, liver]
*Allergic reactions [mostly with penicillin & sulfanomides]
*Disruption in balance of natural microflora > diarrhea/other sx

*Superinfection

78
Q

Drugs starting in Cef, Ceph, Kef are:

A

cephalosporins

79
Q

drugs ended in floxacin are-

A

fluoroquinolones

80
Q

Streptomycin structure is:

A

6 carbon ring with 2 amino sugars

81
Q

Tetracyclines are derived from-

A

streptomyces

82
Q

identify this

A

streptomycin (streptomyces)
[aminoglycoside]

83
Q

identify this

A

chloramphenicol

84
Q

Erythromycin is an example of -

A

a macrolide

85
Q

identify this

A

macrolide

86
Q

identify this

A

sulfonamide

87
Q

how is sulfonamide derived?

A

artificial; from a red dye

88
Q

Polyenes and azoles target

A

fungi

[anti-fungals]

89
Q

identify this

A

Polyenes

90
Q

Polyenes are derived from -

A

streptomyces

91
Q

Monistat is an example of an-

A

Azole (antifungal) [miconazole]

92
Q

The 2 drugs starting with Poly- happen to target:

A

cell membranes

Polymixins- target bacterial cell membranes
Polyenes- target fungal cell membranes

93
Q

quinine was found to treat-

A

Malaria

94
Q

The downside of chloroquines is-

A

microbes are starting to develop resistance to it

95
Q

Metronidazole MOA=

A

breakage of double DNA strands

96
Q

Metronidazole targets-

A

amoebas

97
Q

cyclovirs are chemicals that mimic ____________

so they can act as ______________

A

DNA nucleotides

competitive inhibitors and block DNA replication

98
Q

Most HIV treatment includes-

A

HAART [3 drugs that work in 2+ different ways]

since HIV rapidly mutates

99
Q

interferons are derived from

A

the human body/gene

Microbiology (18 decks)

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