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Question 1

List the ideal characteristics of an ideal antimicrobial drug.

Answer 1

• Toxic to microbe (not to host)
• Microbicidal (rather than microbistatic)
• Soluble
• Effective at low concentrations
• Remains potent/active (not easily degraded/excreted)
• Does not lead to antimicrobial resistance
• Complements/assists the host’s defenses
• Readily delivered to the site of infection
• Reasonably priced
• Hypoallergenic

These characteristics are essential for the effectiveness and safety of antimicrobial drugs.

Question 2

Differentiate between antimicrobial and antibiotic.

Answer 2

Antimicrobial is an all-inclusive term for any antimicrobial drug, regardless of what type of microorganism it targets. Antibiotics specifically inhibit or destroy microorganisms, generally used for drugs targeting bacteria.

Question 3

What is the minimum inhibitory concentration (MIC)?

Answer 3

The smallest concentration (highest dilution) of a drug that visibly inhibits growth.

Question 4

List four methods used to test microorganisms for drug susceptibility.

Answer 4

• Kirby-Bauer technique
• Epsilometer test (E-test)
• Tube dilution test
• Genetic test

Question 5

An organism’s profile of antimicrobial sensitivity.

Answer 5

What is an antibiogram?

Question 6

List at least three reasons why antibiotic treatment may fail.

Answer 6

• Inadequate drug delivery
• Resistant microbes
• Mixed infection

Question 7

The ratio of the dose of the drug that is toxic to humans to its minimum effective dose.

Answer 7

therapeutic index

Question 8

When drugs have similar MICs, which drug has the widest margin of safety?

Answer 8

The drug with the highest TI.

Question 9

What is meant by stating that drugs need to be selectively toxic?

Answer 9

Antimicrobial drugs that are selectively toxic kill or inhibit microbial cells without simultaneously damaging host tissues.

Question 10

List the five primary targets of antibiotics on bacterial cells.

Answer 10

• Protein synthesis
• Cell wall synthesis
• Cell membrane
• DNA/RNA replication
• Folic Acid Synthesis

Question 11

What do β-lactam antibiotics target?

Answer 11

The cell wall of bacteria.

Question 12

List the three β-lactam antibiotic classes.

Answer 12

• Penicillin
• Cephalosporin
• Carbapenem

Question 13

Which bacterial enzyme is inhibited by β-lactam drugs?

Answer 13

Transpeptidase.

Question 14

What is the function of transpeptidase?

Answer 14

Forms covalent bonds between peptide side chains during peptidoglycan synthesis.

Question 15

Which bacterial enzyme inhibits penicillin?

Answer 15

β-lactamase (i.e. penicillinase).

Question 16

Penicillin antibiotics end in the suffix _____.

Answer 16

-cillin.

Question 17

Cephalosporin antibiotics have root names _____.

Answer 17

cef–, ceph–, or kef–.

Question 18

What does the antibiotic isoniazid inhibit?

Answer 18

The synthesis of mycolic acid.

Question 19

What is the main active ingredient in Neosporin®?

Answer 19

Bacitracin.

Question 20

List the five mechanisms of protein synthesis inhibition.

Answer 20

• Prevent initiation/ribosome assembly
• Misread mRNA
• Prevent peptide transfer
• Block tRNA entry
• Prevent translocation

Question 21

List the three antibiotics that inhibit protein synthesis by targeting the 30S ribosomal subunit.

Answer 21

• Aminoglycosides
• Tetracyclines
• Glycylcyclines

Question 22

What do aminoglycosides do?

Answer 22

Lead to misreading of the mRNA.

Question 23

Examples of aminoglycosides include:

Answer 23

• Streptomycin
• Kanamycin
• Neomycin
• Gentamicin

Question 24

What do tetracyclines prevent?

Answer 24

tRNA from entering the A site.

Question 25

Examples of tetracyclines include:

Answer 25

* Tetracycline * Oxytetracycline

Question 26

What do glycylcyclines prevent?

Answer 26

tRNA from entering the A site.

Question 27

Example of a glycylcycline is:

Answer 27

Tigecycline.

Question 28

What do macrolides prevent?

Answer 28

Peptidyl transfer and ribosomal translocation.

Question 29

What class of antibiotics inhibits folic acid synthesis?

Answer 29

Sulfonamides.

Question 30

Fluoroquinolone antibiotics stop DNA transcription by inhibiting _____.

Answer 30

DNA unwinding enzymes.

Question 31

Provide at least two examples of fluoroquinolones.

Answer 31

* Nalidixic acid * Ciprofloxacin * Ofloxacin * Levofloxacin * Trovafloxacin

Question 32

What does the antibiotic Rifamycin target?

Answer 32

RNA Polymerase.

Question 33

Examples of antibacterial drugs that target cell membranes are:

Answer 33

* Polymyxin B * Polymyxin E * Daptomycin

Question 34

List the four main groups of antifungals.

Answer 34

* Macrolide polyenes * Azoles * Echinocandins * Allylamines

Question 35

What is the mechanism of action of macrolide polyenes?

Answer 35

Form pores in cell membranes.

Question 36

Why are viral infections so difficult to treat?

Answer 36

Poor selective toxicity.

Question 37

List the three major antiviral targets.

Answer 37

* Entry inhibitors * Synthesis inhibitors * Maturation inhibitors

Question 38

What do Enfuvirtide (Fuzeon), Zanamivir (Relenza), Remdesivir, and Oseltamivir (Tamiflu) have in common?

Answer 38

They are all examples of viral entry inhibitors.

Question 39

Define the term nucleotide analog.

Answer 39

Nucleotide analogs are fake nucleotides that polymerase mistake for functional nucleotides during nucleic acid synthesis.

Question 40

Provide an example of a nucleotide analog antiviral drug for herpesvirus.

Answer 40

Acyclovir.

Question 41

Provide an example of a nucleotide analog antiviral drug for hemorrhagic fevers.

Answer 41

Ribavirin.

Question 42

Provide an example of a nucleotide analog antiviral drug for HIV.

Answer 42

Zidovudine (AZT).

Question 43

HIV reverse transcriptase inhibitors include _____.

Answer 43

Nucleotide analogs and non-nucleotide analogs.

Question 44

List the two methods by which microorganisms develop drug resistance.

Answer 44

* Spontaneous mutations * Horizontal gene transfer

Question 45

List the five drug resistance mechanisms.

Answer 45

* Inactivate drug * Inhibit drug entry * Eliminate drug * Mutate drug binding targets * Alternative synthesis pathway

Question 46

What is a somewhat unnasty method of treating recurring Clostridium difficile infections?

Answer 46

Fecal transplant.

Question 47

Choose the method of antimicrobial susceptibility testing that involves measuring zones of inhibition.

Answer 47

Kirby-Bauer test.

Question 48

Select the methods of antimicrobial susceptibility testing that can be used to determine minimal inhibitory concentrations (MIC).

Answer 48

* Etest * Tube dilution test

Question 49

Choose the antibiotic that would be the best option for treatment given similar MICs: Antibiotic W TI = 5 Antibiotic X TI = 20 Antibiotic Y TI = 100 Antibiotic Z TI = 10.

Answer 49

Antibiotic Y.

Question 50

The feature of an antimicrobial that allows it to kill or inhibit microbes yet be harmless to the host is referred to as _____.

Answer 50

Selective toxicity.

Question 51

A narrow-spectrum antimicrobial would be an appropriate choice to treat an abscess caused by several different microbe species, including both gram-negative and gram-positive bacteria. T/F

Answer 51

False.

Question 52

The use of a drug to prevent imminent infection is called _____.

Answer 52

Prophylaxis.

Question 53

The production of antibiotics by microbes evolved so that _____.

Answer 53

The growth of other organisms sharing their habitat was inhibited, thus giving them a selective advantage.