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HLSC 124 - Microbiology for Health Professionals > Chapter 20 - Antimicrobial Drugs > Flashcards

Chapter 20 - Antimicrobial Drugs Flashcards

1
Q

Antibiotic

A

-a substance produced by microorganisms that in small amounts inhibits other microorganisms

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2
Q

Antibiotic Resistance

A

-formerly effective medications have less and less impact on bacteria

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3
Q

Narrow Spectrum of Microbial Activity

A

-a small range of different microbial types they affect

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4
Q

Broad-Spectrum Antibiotics

A

-have a wide range of bacteria they affect

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5
Q

Hydrophilic Drugs

A

-drugs that pass through the porin channels
-relatively small

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6
Q

Lipophilic Drugs

A

-larger
-don’t enter gram negative bacteria readily

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7
Q

Bactericidal

A

-kill microbes directly

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8
Q

Bacteriostatic

A

-prevent microbes from growing
-hosts own defences destroy the microorganism

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9
Q

Cell Wall Synthesis Inhibition

A

-bacterial cell walls have peptidoglycan
-synthesis of PG is inhibited
-cell wall is weakened and undergoes lysis
-only growing cells are affected
-ie. penicillin

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10
Q

Protein Synthesis Inhibition

A

-difference in ribosomal structure accounts for selective toxicity
-ie. chloramphenicol

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11
Q

Eukaryotic Cell Ribosomes

A

-80S
-However, mitochondria have 70S ribosomes and hence host cells may be affected

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12
Q

Prokaryotic Cell Ribosomes

A

-have 70S ribosomes

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13
Q

Plasma Membrane Injury

A

-changes in membrane permeability
-results in loss of important metabolites from the cell

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14
Q

Nucleic Acid Synthesis Inhibition

A

-interfere with DNA replication and transcription
-block bacteria RNA polymerase

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15
Q

Essential Metabolite Synthesis Inhibition

A

-competitive inhibition by a substance that closely resembles the enzyme
-ie. PABA

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16
Q

What part of the cell does penicillin affect?

A

cell wall

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17
Q

How do penicillin and cephalosporins act?

A

-they inhibit polypeptide bonds
-cause osmotic lysis

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18
Q

What two drugs interact with the cell wall?

A

penicillin and cephalosporins

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19
Q

What common core structure do penicillins have?

A

-a nucleus containing a β-lactam ring

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20
Q

Does penicillin affect more gram+ or gram- bacteria?

A

gram-positive

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21
Q

Which prototype do we get all penicillin species from?

A

-Penicillin G (natural penicillin)

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22
Q

Penicillin G has a ________ spectrum

A

narrow

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23
Q

Penicillin G is often the drug of choice against most _______, _______, and _______.

A

staphylococci, streptococci, and several spirochetes

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24
Q

What is a problem with penicillin G?

A

it has to be injected

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25
Q

Why can’t penicillin G be given orally?

A

it will be dissolved by stomach acids

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26
Q

Penicillin V is given…

A

-orally; stable in stomach acids

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27
Q

Penicillinase: β-lactamases

A

-enzymes produced by many bacteria that cleave the β-lactam ring

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28
Q

Which species mostly produces β-lactamase?

A

Staphylococcus aureus

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29
Q

Why were semi-synthetic penicillins developed?

A

in attempt to overcome disadvantages of natural penicillin

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30
Q

What organism is resistant to methicillin?

A

Methicillin-resistant Staphylococcus aureus (MRSA)

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31
Q

Advantage of Oxacillin

A

-resistant to penicillinase

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32
Q

Disadvantage of Oxacillin

A

has a narrow spectrum (gram+ only)

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33
Q

What are the two aminopenicillins?

A

ampicillin and amoxicillin

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34
Q

What is the advantage of ampicillin?

A

it has a broad spectrum of many gram- bacteria

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35
Q

What are the 2 main adverse effects of penicillin?

A

allergies and resisitance

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36
Q

How do cephalosporins attack?

A

-inhibit cell wall synthesis

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37
Q

Advantage of cephalosporins over penicillin?

A

-they are resistant to enzymes

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38
Q

What is the limiting factor of cephalosporins?

A

they are expensive because they are extracted from nature

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39
Q

What are cephalosporins often used to treat?

A

meningitis (treated by 3rd gen.)

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40
Q

What are cephalosporin generations?

A

-the semi-forms, not names

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41
Q

Each generation of cephalosporin has an ______ spectrum?

A

-increased
-ie. 5th gen is better than the 1st

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42
Q

What are the adverse effects of cephalosporins?

A

-mild GI tract symptoms (nausea, extreme vomiting)

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43
Q

What does chloramphenicol inhibit?

A

-protein synthesis
-inhibit the formation of peptide bonds (dehydration synthesis) in the polypeptide chain

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44
Q

How does chloramphenicol shut off protein synthesis?

A

-attaches to the 50S portion of the 70S prokaryotic ribosomes

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45
Q

What is an advantage of chloramphenicol?

A

-they are less expensive and have a simple structure that can be prepared in the lab

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46
Q

Chloramphenicol has a __________ spectrum.

A

broad

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47
Q

Chloramphenicol has a ________ size so it can…

A

-small size
-it can diffuse into areas of the body that are inaccessible to other drugs

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48
Q

Chloramphenicol can penetrate the ____

A

Blood brain barrier

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49
Q

What is chloramphenicol used to treat often?

A

meningitis

50
Q

Adverse Effects of Chloramphenicol

A

-Aplastic anemia
-Grey Baby Syndrome

51
Q

Aplastic Anemia

A

-suppression of bone marrow activity
-bone marrow can’t make enough new blood cells
-rare and often fatal

52
Q

Grey Baby Syndrome

A

-abdominal distension
-hemodynamic collapse
-ashy skin discolouration

53
Q

What does Erythromycin inhibit?

A

-protein synthesis
-attaches to 50S subunit and inhibits ribosomal movement to read mRNA

54
Q

Erythromycin has a ________ spectrum

A

broad

55
Q

Macrocyclic

A

-a property of erythromycin
-….

56
Q

Which drug is used often used with penicillin allergies?

A

Erythromycin

57
Q

What is an advantage of Erythromycin for children?

A

-it can be flavoured

58
Q

What is Erythromycin often used to treat?

A

-strep throat
-legionellosis
-mycoplasmal pneumonia
-other gram+ bacteria

59
Q

What type of bacteria can erythromycin not penetrate the cell wall of?

A

gram negative bacteria

60
Q

Adverse effect of Erythromycin:

A

mild GI tract symptoms (affect 2-3% of users)

61
Q

What group of antibiotics does erythromycin fall under?

A

macrolides

62
Q

What does streptomycin inhibit?

A

-initial steps protein synthesis
-change shape of 30S portion of the 70S prokaryotic ribosomes
-change shape of mRNA so it is read incorrectly

63
Q

What bacteria are streptomycin commonly used on?

A

gram negative

64
Q

What group does streptomycin fall under?

A

amino glycoside

65
Q

What was streptomycin used to treat?

A

TB and leprosy

66
Q

_________ is a major issue with streptomycin

A

resistance

67
Q

What are the adverse effects of streptomycin?

A

-deafness
-kidney failure

68
Q

What does tetracycline inhibit?

A

-protein synthesis
-interferes with attachment of the tRNA carrying the amino acids to the ribosome at the 30s portion
-prevents addition of amino acids to the polypeptide chain

69
Q

Tetracyclines do not interfere with mammalian ribosomes but can affect ____________ ribosomes.

A

mitochondrial

70
Q

Tetracyclines are effective against gram _________ bacteria

A

gram negative and gram positive

71
Q

Tetracyclines penetrate ______ tissues well

A

-body tissues
-effective in treating intracellular ricksettias and chlamydias

72
Q

Which antimicrobial agent has the broadest spectrum but the most adverse effects?

A

tetracycline

73
Q

What is the drug of choice for STDs?

A

tetracycline (used for chlamydial, syphilis, gonorrhoea)

74
Q

How does tetracycline enter the food chain and produce human resistance?

A

-it is used by farmers in animal feed to protect the animals from disease

75
Q

What is the advantage of semisynthetic tetracyclines, such as doxycycline?

A

longer retention in the body

76
Q

Adverse effects of tetracycline

A

-more likely these effects will occur
-destroys natural bacteria in GI tract, leads to severe diarrhea
-secondary fungal infections
-pregnancy
-teeth damage, binds to calcium

77
Q

Why is tetracycline dangerous during pregnancy?

A

-dangerous for mothers lungs, kidneys, liver
-affects baby bone formation (skull shape)

78
Q

Other than STDs what is tetracycline use to treat?

A

-UTIs
-Mycoplasmal pneumonia
-Ricksettial infections

79
Q

Superinfections

A

-caused by tetracycline
-suppress normal intestinal microbiota
-fungal infection

80
Q

Which four drugs affect protein synthesis?

A

chloramphenicol, erythromycin, streptomycin, tetracycline

81
Q

What is the action of Polymyxin?

A

-plasma membrane synthesis
-breaks down fatty acids and building blocks
-the cell contents leak out
-cell dies

82
Q

What type of bacteria does polymyxin act on?

A

gram negative

83
Q

How does polymyxin attach?

A

-binds to the outer membrane

84
Q

What are the adverse effects of polymyxin?

A

toxic to kidneys

85
Q

What is a disadvantage of polymyxin?

A

-it can only be given topically, not systemically

86
Q

Which two drugs target nucleic acid synthesis?

A

rifampin and the group of quinolones and fluoroquinolone

87
Q

How does Rifampin inhibit nucleic acid synthesis?

A

-inhibit mRNA synthesis
-inhibits RNA polymerase
-leads to no transcription and hence no protein synthesis

88
Q

What is Rifampin used to treat?

A

-mycobacterium sp.
-TB and leprosy

89
Q

What is an advantage of Rifampin?

A

-it can penetrate tissues and reach CSF and abscesses

90
Q

Adverse Effects of Rifampin

A

-liver damage (when given high dose)
-during pregnancy and puberty
-red urine, feces, saliva, sweat, tears

91
Q

What is the acronym for determining which drugs are dangerous during pregnancy?

A

SAFE Moms Take Really Good Care

92
Q

What does ‘SAFE Moms Take Really Good Care’ Stand for?

A

-Sulfonamides
-Aminoglycosides
-Fluoroquinolones
-Erythromycin
-Metronidazole
-Tetracyclines
-Ribavirin
-Griseofulvin
-Chloramphenicol

93
Q

How do (fluoro)quinolones act?

A

-inhibit nucleic acid synthesis
-selectively inhibits DNA gyrase enzyme needed for DNA replication

94
Q

What is fluoroquinolone?

A

-a synthetic quinolone
-has increased penetration abilities

95
Q

What are fluoroquinolones used to treat?

A

-UTIs
-pneumonia
-Shigellosis

96
Q

Adverse Effects of Fluoroquinolones

A

-can rupture tendons
-impair cartilage growth and cause joint pain and weakness

97
Q

When are physicians advised to use fluoroquinolones?

A

-when there is no other treatment option

98
Q

Fluoroquinolones have a high likely of developing ___________, rapidly.

A

resistance

99
Q

How do Sulfa drugs and Trimethoprim act?

A

-inhibit cells ability to synthesize metabolites
-inhibit folic acid synthesis, no DNA or RNA made
-cell dies

100
Q

What are sulfa and trimethoprim used to treat?

A

UTIs

101
Q

What folic acid precursor is Sulfa similar to?

A

-PABA
-they competitively inhibit PABAs enzyme to block folic acid production

102
Q

Why doesn’t sulfa harm human cells?

A

-we get folic acid from our diet rather than synthesizing it

103
Q

What is another name for Sulfa drugs?

A

Sulfonamides

104
Q

What is a common adverse effect of Sulfa and trimethoprim?

A

-high occurrence of allergy

105
Q

Sulfa Adverse Effects

A

-pregnancy (neurological damage)
-liver damage
-anemia
-allergy

106
Q

Trimethoprim Adverse Effects

A

-jaundice
-allergy

107
Q

How do antiviral drugs act?

A

-they are nucleoside (DNA or RNA) analogs
-they mimic nucleotides to decrease viral load

108
Q

Nucleoside Analog

A

-resemble natural nucleosides
-base and sugar combination
-pick up a phosphate when they enter the body to create a false nucleotide

109
Q

Entry Inhibitors

A

drugs that block the initial steps in viral infection (absorption and penetration)

110
Q

How do entry inhibitors treat HIV?

A

-target receptors HIV uses to bind

111
Q

What is a common target for nucleic acid inhibiton?

A

-enzyme reverse transcriptase because it is not in human DNA synthesis

112
Q

What is the base of Acyclovir?

A

-guanine

113
Q

What is Acyclovir used to treat?

A

-Herpes 2 (the STD)

114
Q

What is the base of ganciclovir?

A

guanine

115
Q

What is ganciclovir used to treat?

A

Herpes 5 (CMV - cytomegalovirus; an infection of the eye)

116
Q

What is the base of Ribavirin?

A

guanine

117
Q

What is Ribavirin used to treat?

A

influenza, Hep C

118
Q

What is the base of Lamivudine?

A

thymine

119
Q

What is lamivudine used to treat?

A

Hep B

120
Q

What is the base of Azidothymidine?

A

thymine

121
Q

What is Azidothymidine used to treat?

A

HIV

HLSC 124 - Microbiology for Health Professionals (18 decks)

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