Micro Test 2

Front 1

Selectively toxic

Back 1

Kill or inhibit growth of microorganisms, while causing as little damage to the host as possible

Front 2

Therapeutic Index (TI)

Back 2

-Measure of drug effectiveness
-Higher TI, better chemotherapeutic agent
-Higher TI, fewer side effects (undesirable effects to host)
-Higher TI drugs act against component in microorganism not found in host

Front 3

Classification of Drugs

Back 3

1. Organisms they attack
2. Synthetic vs. Natural
3. Means of action
-static or -cidal

Front 4

Minimal Inhibitory Concentration (MIC)
Minimal Lethal Concentration (MLC)

Back 4

-[lowest] needed to inhibit growth
-[lowest] needed to kill microorganism

Front 5

Five Activities of Antibiotics

Back 5

1) Inhibit cell wall synthesis

2) Destroy or inhibit cell membrane activity

3) Inhibit nucleic acid synthesis

4) Inhibit protein synthesis

5) Interfere with metabolism

Front 6

Antibiotics that Inhibit Cell Wall Synthesis

Back 6

Penicillins
Cephalosporins
Bacitracin
Vancomycin

Front 7

Penicillins

Back 7

-inhibit cell wall
-fungus Penicillinium
-b-lactam ring
-Bacteriocidal
-natural and semi-synthetic

Front 8

Natural penicillins

Back 8

ex:Penicillin G
-Narrow-spectrum
-Destroyed by stomach acid

Front 9

Semi-Synthetic penicillins

Back 9

ex:Ampicillin
-Broad-spectrum
-Less susceptible to stomach acid

Front 10

Mechanism of Penicillin

Back 10

-Resembles terminal D-alanine in peptidoglycan
blocks peptide bridges
only effective against actively growing cells
-Can activate cell wall lytic enzymes

Front 11

Resistance to Penicillins

Back 11

-b-lactamases
-Gram - have intrinsic resistance

Front 12

Side Effects of Penicillin

Back 12

-Toxic at high doses
-Allergies

Front 13

Cephalosporins

Back 13

-inhibit cell wall
-fungus Cephalosporium
-b-lactam ring
-Bacteriocidal
-given to patients with penicillin allergies
-Broad-spectrum

Front 14

Bacitracin

Back 14

-From Bacillus
-Narrow-spectrum
-Bacteriocidal
-Toxic to kidney
-Blocks dephosphorylation of bactoprenol pyrophosphate (causes cell wall failure)

Front 15

Vancomycin

Back 15

-From Streptomyces
-Type of Glycopeptide Antibiotic
-Narrow-spectrum
-Bacteriocidal
-Given both orally and intravenously
-Blocks transpeptidation of peptidoglycan

Front 16

Antibiotic that Destroy or Inhibit Cell Membrane Activity

Back 16

Polymixin B

Front 17

Polymixin B

Back 17

-From Bacillus
-Bacteriocidal
-Narrow-spectrum
-Toxic to kidney
-Binds to outer layer of plasma membrane
destroys semi-permeability

Front 18

Antibiotics that Inhibit Nucleic Acid Synthesis (two types)

Back 18

A) Inhibit DNA Synthesis
B) Inhibit RNA Synthesis

Front 19

Inhibit DNA Synthesis

Back 19

1) Quinolones
2) Novobiocin
3) Mitomycin C

Front 20

Quinolones

Back 20

-Contain 4-quinalone ring
-Synthetic
-Bacteriocidal
-Broad-spectrum (both gram - & gram +)
-Oral administration
-Used to treat diseases of GI, urinary & respiratory tracts, skin
-Common side effects: GI upset, allergic response
-Inhibit DNA gyrase enzyme

Front 21

Novobiocin

Back 21

-Bacteriocidal
-Very effective vs. gram + organisms
-Interferes with DNA supercoiling

Front 22

Mitomycin C

Back 22

EXTREMELY toxic
A) Crosslinks two DNA strands
B) Alkylate DNA chains

Front 23

Inhibit RNA Synthesis

Back 23

1) Actinomycin D
2) Rifampicin

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Actinomycin D

Back 24

Binds to guanines in DNA
Blocks RNA polymerase enzyme

Front 25

Rifampicin

Back 25

Bacteriostatic
Binds to and inactivates RNA polymerase
Useful vs. Mycobacterium

Front 26

Antibiotics that Inhibit Protein Synthesis

Back 26

A) Bind to 30S Subunit
B) Bind to 50S Subunit

Front 27

Bind to 30S Subunit

Back 27

1) Tetracycline
2) Aminoglycosides

Front 28

Tetracycline's

Back 28

-From Streptomyces
-Common 4 ring structure
-Broad-spectrum
-Bacteriostatic
-Effective only against actively dividing bacteria
-Binds to 30S ribosome

Front 29

Aminoglycosides

Back 29

Bind to 30S subunit
-All bactericidal
-Mechanisms
1) Directly inhibit protein synthesis
2) Cause misreading of mRNA message
-Some cells develop resistance & dependence
-Side Effects

Front 30

Erythromycin

Back 30

-Type of Macrolide Antibiotic
-From Streptomyces
-Bacteriostatic
-Narrow-spectrum
-Prevents binding of 50S to 30S  70S by binding to 23S rRNA of 50S subunit
-Used in those who can’t tolerate penicillin
-Used to treat whooping cough, diphtheria, pneumonia (Legionella, Mycoplasma)

Front 31

Chloramphenicol

Back 31

-Bind to 50S subunit
-From Streptomyces
-Bacteriostatic
-Very broad-spectrum (gram +, gram -, Chlamydia, Rickettsia)
-Inhibits peptidyl transferase activity (peptide bond formation)
-Side Effects
1) Allergic response
2) Temporary or permanent decrease in bone marrow function
Can lead to aplastic anemia, decreased blood leukocytes, leukemia
-Used only in life-threatening situations

Front 32

Antibiotics that Interfere with Metabolism

Back 32

A) Sulfa drugs
B) Trimethoprim

Front 33

Sulfa drugs

Back 33

-Interfere with metabolism
-Examples) sulfonamides
-Synthetic
-Broad-spectrum (both gram- & gram +)
-Bacteriostatic
-Antimetabolites
Structurally similar to an essential intermediate of metabolism
Competitively inhibits that metabolic pathway
Example) sulfanilamide structurally similar to p-aminobenzoic acid (PABA)
PABA is precursor in synthesis of folate (B vitamin)
Sulfanilamide inhibits folate synthesis
Only effective against bacteria that synthesize their own folate
-Humans can’t make folate, sulfa drugs do not affect

Front 34

Trimethoprim

Back 34

-interferes with metabolism
-Synthetic antibiotic that also interferes with folic acid production
-Broad spectrum
-Can be combined with sulfa drugs to increase efficacy of treatment
Combination blocks two steps in folic acid pathway
-Has a variety of side effects including abdominal pain and photosensitivity reactions

Front 35

Antifungal drugs

Back 35

2 types:
A) superficial mycoses
B) systemic mycoses

Front 36

Superficial mycoses

Back 36

1) Imidizoles
2) Nysatin
3) Griseofulvin

Front 37

Imidizoles

Back 37

-Superficial mycoses
-Miconazole, ketoconazole, clotrimazole
-Found in creams or solutions (spray)
-Broad-spectrum
-Treat athlete’s foot & jock itch (Tinea), vaginal yeast infections
-Inhibit sterol synthesis
Disrupts fungal membrane permeability

Front 38

Nysatin

Back 38

-superficial mycoses
-Polyene drug from Streptomyces
-Topical or oral
-Treat Candidia (thrush) infections of skin, mouth, and vagina
-Inserts into cell membrane & binds to sterols, causing leakage

Front 39

Griseofulvin

Back 39

-superficial mycoses
-From Penicillinium
-Given orally to treat chronic superficial mycoses
-Disrupt mitotic spindle fibers
Inhibit cell division

Front 40

Systemic mycoses

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1) Amphotericin
2) 5-Flucytosine

Front 41

Amphotericin B

Back 41

-From Streptomyces
-Binds to sterols, disrupts membrane permeability
-Very toxic

Front 42

5-Flucytosine

Back 42

-Synthetic
-Converted to 5-fluorouracil by fungus
-Disrupts RNA function
-Resistance often developed quickly

Front 43

Antiviral drug

Back 43

1) Amantidine (Tamiflu™)
2)Vidarabine
3)Acyclovir
4)Cidofovir
5)Azidothymidine (AZT)
6)Ritonavir, Indinavir
7)Enfuvirtide (Fuzeon™)

Front 44

Amantidine

Back 44

-Blocks penetration of influenza virus into respiratory epithelium
-If given within 24-48 hours of exposure, can reduce incidence of flu by 50-70%

Front 45

Vidarabine

Back 45

-Treat herpes infection
-Disrupts viral DNA polymerase activity
-Ointment or intravenous

Front 46

Acyclovir

Back 46

-antiviral
-Herpes simplex infections
-When phosphorylated, resembles deoxy-GTP
Inhibits viral DNA polymerase
-Viruses are becoming more resistant
Now have modified derivatives

Front 47

Cidofovir

Back 47

-antiviral
-Broad-spectrum
-Adenovirus, herpes viruses, poxvirus, cytomegalovirus, papilloma virus
-Competitive inhibitor of viral DNA polymerase

Front 48

Azidothymidine (AZT)

Back 48

-antiviral
-Retroviruses (including HIV)
-Inhibits reverse transcriptase
Blocks HIV reproduction

Front 49

Ritonavir, Indinavir

Back 49

-antiviral
-HIV protease inhibitor
-Resembles peptide bond normally cleaved by HIV protease during processing of viral proteins
-Designed from studying tertiary (3-D) structure of protease
-Often used in combination with AZT

Front 50

Enfuvirtide (Fuzeon™)

Back 50

-antiviral
-Approved for use in 2004
-Synthetic peptide of 36 amino acids
-HIV fusion inhibitor drug
-Blocks fusion of HIV with CD4+ T-cells by binding to gp41 and preventing conformational change
-Now included in HAART therapy

Front 51

Antihelminth Drugs

Back 51

1&2) Mebendazole & Thiabendazole
3&4) Pyrantel & Piperazine
5) Ivermectin

Front 52

Mebendazole & Thiabendazole

Back 52

-antihelminth
-Broad-spectrum antiparasitic
-Works on intestinal infections
-Inhibits microtubule function

Front 53

Pyrantel & Piperazine

Back 53

-antihelminth
-Paralyze muscles of roundworms

Front 54

Ivermectin

Back 54

-antihelminth
-Prophylactic treatment for heartworms & roundworms