Chapter 20 - Antimicrobial Drugs Flashcards
1
Q
Antibiotic
A
-a substance produced by microorganisms that in small amounts inhibits other microorganisms
2
Q
Antibiotic Resistance
A
-formerly effective medications have less and less impact on bacteria
3
Q
Narrow Spectrum of Microbial Activity
A
-a small range of different microbial types they affect
4
Q
Broad-Spectrum Antibiotics
A
-have a wide range of bacteria they affect
5
Q
Hydrophilic Drugs
A
-drugs that pass through the porin channels
-relatively small
6
Q
Lipophilic Drugs
A
-larger
-don’t enter gram negative bacteria readily
7
Q
Bactericidal
A
-kill microbes directly
8
Q
Bacteriostatic
A
-prevent microbes from growing
-hosts own defences destroy the microorganism
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
10
Q
Protein Synthesis Inhibition
A
-difference in ribosomal structure accounts for selective toxicity
-ie. chloramphenicol
11
Q
Eukaryotic Cell Ribosomes
A
-80S
-However, mitochondria have 70S ribosomes and hence host cells may be affected
12
Q
Prokaryotic Cell Ribosomes
A
-have 70S ribosomes
13
Q
Plasma Membrane Injury
A
-changes in membrane permeability
-results in loss of important metabolites from the cell
14
Q
Nucleic Acid Synthesis Inhibition
A
-interfere with DNA replication and transcription
-block bacteria RNA polymerase
15
Q
Essential Metabolite Synthesis Inhibition
A
-competitive inhibition by a substance that closely resembles the enzyme
-ie. PABA
16
Q
What part of the cell does penicillin affect?
A
cell wall
17
Q
How do penicillin and cephalosporins act?
A
-they inhibit polypeptide bonds
-cause osmotic lysis
18
Q
What two drugs interact with the cell wall?
A
penicillin and cephalosporins
19
Q
What common core structure do penicillins have?
A
-a nucleus containing a β-lactam ring
20
Q
Does penicillin affect more gram+ or gram- bacteria?
A
gram-positive
21
Q
Which prototype do we get all penicillin species from?
A
-Penicillin G (natural penicillin)
22
Q
Penicillin G has a ________ spectrum
A
narrow
23
Q
Penicillin G is often the drug of choice against most _______, _______, and _______.
A
staphylococci, streptococci, and several spirochetes
24
Q
What is a problem with penicillin G?
A
it has to be injected
25
Why can't penicillin G be given orally?
it will be dissolved by stomach acids
26
Penicillin V is given...
-orally; stable in stomach acids
27
Penicillinase: β-lactamases
-enzymes produced by many bacteria that cleave the β-lactam ring
28
Which species mostly produces β-lactamase?
Staphylococcus aureus
29
Why were semi-synthetic penicillins developed?
in attempt to overcome disadvantages of natural penicillin
30
What organism is resistant to methicillin?
Methicillin-resistant Staphylococcus aureus (MRSA)
31
Advantage of Oxacillin
-resistant to penicillinase
32
Disadvantage of Oxacillin
has a narrow spectrum (gram+ only)
33
What are the two aminopenicillins?
ampicillin and amoxicillin
34
What is the advantage of ampicillin?
it has a broad spectrum of many gram- bacteria
35
What are the 2 main adverse effects of penicillin?
allergies and resisitance
36
How do cephalosporins attack?
-inhibit cell wall synthesis
37
Advantage of cephalosporins over penicillin?
-they are resistant to enzymes
38
What is the limiting factor of cephalosporins?
they are expensive because they are extracted from nature
39
What are cephalosporins often used to treat?
meningitis (treated by 3rd gen.)
40
What are cephalosporin generations?
-the semi-forms, not names
41
Each generation of cephalosporin has an ______ spectrum?
-increased
-ie. 5th gen is better than the 1st
42
What are the adverse effects of cephalosporins?
-mild GI tract symptoms (nausea, extreme vomiting)
43
What does chloramphenicol inhibit?
-protein synthesis
-inhibit the formation of peptide bonds (dehydration synthesis) in the polypeptide chain
44
How does chloramphenicol shut off protein synthesis?
-attaches to the 50S portion of the 70S prokaryotic ribosomes
45
What is an advantage of chloramphenicol?
-they are less expensive and have a simple structure that can be prepared in the lab
46
Chloramphenicol has a __________ spectrum.
broad
47
Chloramphenicol has a ________ size so it can...
-small size
-it can diffuse into areas of the body that are inaccessible to other drugs
48
Chloramphenicol can penetrate the ____
Blood brain barrier
49
What is chloramphenicol used to treat often?
meningitis
50
Adverse Effects of Chloramphenicol
-Aplastic anemia
-Grey Baby Syndrome
51
Aplastic Anemia
-suppression of bone marrow activity
-bone marrow can't make enough new blood cells
-rare and often fatal
52
Grey Baby Syndrome
-abdominal distension
-hemodynamic collapse
-ashy skin discolouration
53
What does Erythromycin inhibit?
-protein synthesis
-attaches to 50S subunit and inhibits ribosomal movement to read mRNA
54
Erythromycin has a ________ spectrum
broad
55
Macrocyclic
-a property of erythromycin
-....
56
Which drug is used often used with penicillin allergies?
Erythromycin
57
What is an advantage of Erythromycin for children?
-it can be flavoured
58
What is Erythromycin often used to treat?
-strep throat
-legionellosis
-mycoplasmal pneumonia
-other gram+ bacteria
59
What type of bacteria can erythromycin not penetrate the cell wall of?
gram negative bacteria
60
Adverse effect of Erythromycin:
mild GI tract symptoms (affect 2-3% of users)
61
What group of antibiotics does erythromycin fall under?
macrolides
62
What does streptomycin inhibit?
-initial steps protein synthesis
-change shape of 30S portion of the 70S prokaryotic ribosomes
-change shape of mRNA so it is read incorrectly
63
What bacteria are streptomycin commonly used on?
gram negative
64
What group does streptomycin fall under?
amino glycoside
65
What was streptomycin used to treat?
TB and leprosy
66
_________ is a major issue with streptomycin
resistance
67
What are the adverse effects of streptomycin?
-deafness
-kidney failure
68
What does tetracycline inhibit?
-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
Tetracyclines do not interfere with mammalian ribosomes but can affect ____________ ribosomes.
mitochondrial
70
Tetracyclines are effective against gram _________ bacteria
gram negative and gram positive
71
Tetracyclines penetrate ______ tissues well
-body tissues
-effective in treating intracellular ricksettias and chlamydias
72
Which antimicrobial agent has the broadest spectrum but the most adverse effects?
tetracycline
73
What is the drug of choice for STDs?
tetracycline (used for chlamydial, syphilis, gonorrhoea)
74
How does tetracycline enter the food chain and produce human resistance?
-it is used by farmers in animal feed to protect the animals from disease
75
What is the advantage of semisynthetic tetracyclines, such as doxycycline?
longer retention in the body
76
Adverse effects of tetracycline
-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
Why is tetracycline dangerous during pregnancy?
-dangerous for mothers lungs, kidneys, liver
-affects baby bone formation (skull shape)
78
Other than STDs what is tetracycline use to treat?
-UTIs
-Mycoplasmal pneumonia
-Ricksettial infections
79
Superinfections
-caused by tetracycline
-suppress normal intestinal microbiota
-fungal infection
80
Which four drugs affect protein synthesis?
chloramphenicol, erythromycin, streptomycin, tetracycline
81
What is the action of Polymyxin?
-plasma membrane synthesis
-breaks down fatty acids and building blocks
-the cell contents leak out
-cell dies
82
What type of bacteria does polymyxin act on?
gram negative
83
How does polymyxin attach?
-binds to the outer membrane
84
What are the adverse effects of polymyxin?
toxic to kidneys
85
What is a disadvantage of polymyxin?
-it can only be given topically, not systemically
86
Which two drugs target nucleic acid synthesis?
rifampin and the group of quinolones and fluoroquinolone
87
How does Rifampin inhibit nucleic acid synthesis?
-inhibit mRNA synthesis
-inhibits RNA polymerase
-leads to no transcription and hence no protein synthesis
88
What is Rifampin used to treat?
-mycobacterium sp.
-TB and leprosy
89
What is an advantage of Rifampin?
-it can penetrate tissues and reach CSF and abscesses
90
Adverse Effects of Rifampin
-liver damage (when given high dose)
-during pregnancy and puberty
-red urine, feces, saliva, sweat, tears
91
What is the acronym for determining which drugs are dangerous during pregnancy?
SAFE Moms Take Really Good Care
92
What does 'SAFE Moms Take Really Good Care' Stand for?
-Sulfonamides
-Aminoglycosides
-Fluoroquinolones
-Erythromycin
-Metronidazole
-Tetracyclines
-Ribavirin
-Griseofulvin
-Chloramphenicol
93
How do (fluoro)quinolones act?
-inhibit nucleic acid synthesis
-selectively inhibits DNA gyrase enzyme needed for DNA replication
94
What is fluoroquinolone?
-a synthetic quinolone
-has increased penetration abilities
95
What are fluoroquinolones used to treat?
-UTIs
-pneumonia
-Shigellosis
96
Adverse Effects of Fluoroquinolones
-can rupture tendons
-impair cartilage growth and cause joint pain and weakness
97
When are physicians advised to use fluoroquinolones?
-when there is no other treatment option
98
Fluoroquinolones have a high likely of developing ___________, rapidly.
resistance
99
How do Sulfa drugs and Trimethoprim act?
-inhibit cells ability to synthesize metabolites
-inhibit folic acid synthesis, no DNA or RNA made
-cell dies
100
What are sulfa and trimethoprim used to treat?
UTIs
101
What folic acid precursor is Sulfa similar to?
-PABA
-they competitively inhibit PABAs enzyme to block folic acid production
102
Why doesn't sulfa harm human cells?
-we get folic acid from our diet rather than synthesizing it
103
What is another name for Sulfa drugs?
Sulfonamides
104
What is a common adverse effect of Sulfa and trimethoprim?
-high occurrence of allergy
105
Sulfa Adverse Effects
-pregnancy (neurological damage)
-liver damage
-anemia
-allergy
106
Trimethoprim Adverse Effects
-jaundice
-allergy
107
How do antiviral drugs act?
-they are nucleoside (DNA or RNA) analogs
-they mimic nucleotides to decrease viral load
108
Nucleoside Analog
-resemble natural nucleosides
-base and sugar combination
-pick up a phosphate when they enter the body to create a false nucleotide
109
Entry Inhibitors
drugs that block the initial steps in viral infection (absorption and penetration)
110
How do entry inhibitors treat HIV?
-target receptors HIV uses to bind
111
What is a common target for nucleic acid inhibiton?
-enzyme reverse transcriptase because it is not in human DNA synthesis
112
What is the base of Acyclovir?
-guanine
113
What is Acyclovir used to treat?
-Herpes 2 (the STD)
114
What is the base of ganciclovir?
guanine
115
What is ganciclovir used to treat?
Herpes 5 (CMV - cytomegalovirus; an infection of the eye)
116
What is the base of Ribavirin?
guanine
117
What is Ribavirin used to treat?
influenza, Hep C
118
What is the base of Lamivudine?
thymine
119
What is lamivudine used to treat?
Hep B
120
What is the base of Azidothymidine?
thymine
121
What is Azidothymidine used to treat?
HIV
