Chapter 20 Antimicrobial Medications

(T/F) All antibiotics are made by fungi such as Penicillium and Cephalosporium.

False

Antiviral medications that interfere with viral nucleic acid synthesis often appear very similar to which compound?

Nucleosides

Which of the following is the target of methicillin?

Peptidoglycan synthesis

Please match the terms regarding drug therapies with their definitions.

1. Antimicrobial drug

2. Antibiotic

3. Chemotherapeutic agent

4. Breakthrough therapy

1. Antibiotic

2. Chemotherapeutic agent

3. Antimicrobial drug

4. Breakthrough therapy

Match the antimicrobial medications with the ribosomal subunit to which they bind. Not all labels are used.

50s:-Lincosamides, Oxazolidinones, Streptogramins, Chloramphenicol, Macrolides.

30s:-Tetracyclines, Glycylcyclines Aminoglycosides.

All of the following about the Kirby-Bauer test are true EXCEPT

(???)

each disc contains a known amount of antibiotic.

Malarone is a synergistic combination of atovaquone and proguanil hydrochloride that interferes with mitochondrial activity. Given this information, which of the following statements are TRUE?

- Given its mechanism of action, malarone would be effective against protozoa.

- The therapeutic effect of malarone is better than either atovaquone or proguanil hydrochloride.

Which step(s) in the figure below is/are targeted by antiviral medications such as acyclovir, ribavirin, and AZT?

Step 3

Analyze the results of the Kirby-Bauer disc diffusion test seen in this image, and then answer all questions that follow here.

1. The Kirby-Bauer disc diffusion test is used to determine

2. During incubation, antimicrobials applied to the bacterial lawn become increasingly ______ as they diffuse out of the disc into the medium.

3. The area of clearing around the discs is called the zone of

4. The ______ of the zone of inhibition is always measured in ______.

5. Which of the medications tested in the above image is/are a beta-lactam antibiotic(s)?

6. Which of the following medications created the largest zone of inhibition?

7. Please evaluate the test organism's sensitivity to chloramphenicol.

8. What is the test organism's level of sensitivity to tetracycline?

1. antimicrobial susceptibility.

2. diluted

3. inhibition

4. diameter, mm

5. Ampicillin

6. Chloramphenicol

7. Sensitive

8. Intermediate

Which of the statements about combination therapy is FALSE?

Using two medications is always twice as effective as using just one.

Which of the following microbes, a leading cause of pneumonia in the United States, is of growing concern due to increased resistance to penicillin?

Streptococcus pneumoniae

Which of the following antimicrobials inhibit bacterial metabolic pathways such as folate biosynthesis?

- SulfonamidesSulfonamides

- Trimethoprim

(T/F) Antiviral medications that interfere with genome integration will be useful against all animal viruses.

False

Please select all the TRUE statements about developing new antimicrobial medications.

- Most recently approved new medications are chemically modified versions of existing medications.

- Developing a new antimicrobial medication is financially risky for a company because target microbes may develop resistance.

Match the following terminologies with their descriptions.

1. This term is used to describe compounds that cause greater harm to microbes than to the human host.

2. This term is used to describe the molecular method by which a compound might kill or inhibit a microbe.

3. This term is used to describe the range of different microbes that a compound can kill or inhibit.

1. Selective toxicity

2. Antimicrobial action

3. Spectrum of activity

The MIC is

the lowest concentration of an antimicrobial medication needed to prevent visible growth of a given bacterial strain in vitro.

Please choose the method of antimicrobial susceptibility testing that involves measuring and evaluating zones of inhibition around antibiotic discs placed on a culture of bacteria prior to incubation.

Kirby-Bauer test

Few medications are effective against Mycobacterium tuberculosis. Please check all the statements explaining why this situation exists.

- M. tuberculosis has developed resistance to many medications.

- M. tuberculosis has a slow generation time.

- The cell wall of M. tuberculosis prevents entry of medications.

Identify all the ways that could help slow the emergence and spread of antimicrobial resistance.

- Educate patients on the proper use of prescribed drugs (don't skip a dose).

- Encourage stricter regulations of medications in developing countries.

- Train healthcare workers to use proper handwashing and other hygiene measures when dealing with patients.

- Encourage appropriate administration of drugs (don't over prescribe).

Match the labels with the correct areas it describes in this image of an E (epsilometer) test. Not all labels are used.

Top to Bottom:

1) Type of antibiotic indicated here

2) Highest antibiotic concentration

3) MIC value read here

4) Lowest antibiotic concentration

The Kirby-Bauer test is used to determine

(???)

the response of a microbe to a medication.

Which of the following antimicrobials target the bacterial cytoplasmic membrane?

- Daptomycin

- Streptomycin

- Streptomycin

Please select the antifungal agents from the choices below.

- Aminoglycosides

- Macrolide polyenes

- Azoles

- Echinocandins

- Flucytosine

The distribution and metabolism of some antimicrobials can be adversely affected by

- Different pH conditions in some areas of the body. different pH conditions in some areas of the body

- Quick metabolism by the patient's enzymes. quick metabolism by the patient's enzymes

- The ability of the host to metabolize the medication quickly

Key Concept Activity: Match the antibacterial medications listed with the correct cellular target. Not all labels are used.

Top:

Left - β-lactam antibiotics, Glycopeptide antibiotics, Bacitracin

Right - Fluoroquinolones, Rifamycins

Bottom:

Left - Polymyxins, Daptomycin

Middle - Sulfonamides, Trimethoprim

Right - Aminoglycosides, Tetracyclines and glycylcyclines, among others

Which of the following statements about antibiotic resistance is FALSE?

Patients should stop taking antibiotics as soon as they feel better, to avoid developing resistance.

Most antiparasitic medications target ______.

biosynthetic pathways

What is the disadvantage of an antibiotic with a short half-life?

It must be given multiple times daily.

Which of the following medications inhibits bacterial cell wall synthesis?

- Penicillin

- Vancomycin

- Bacitracin

Please choose the class of antimicrobials that would have the most selective toxicity.

Antimicrobials that inhibit cell wall synthesis

A researcher develops a new medication that acts by inhibiting microtubule formation (involved in mitosis). For diseases caused by which of the following pathogens would this medication NOT be used?

Staphylococcus aureus

Which of the following is of growing concern due to increasing resistance to vancomycin?

Enterococci

Which are obstacles in the development of new drugs?

- Developing new drugs is very expensive because of required clinical testing trials needed for FDA approval

New drugs may not be used commonly

- They are reserved as last resort options. this reduces the money made by the production company.

- Microbes becomes resistant to any new medications that are developed because the time taken to get approval for their use is so long

Which of the following statements about antibiotics is FALSE?

Antibiotics prevent capsid formation during viral replication.

Which of the following antimicrobial medications inhibit nucleic acid synthesis in bacteria?

- Rifamycins

- Metronidazole

- Fluoroquinolones

Helminth and protozoan diseases are difficult to treat because the cells of these organisms

are structurally and functionally similar to human cells.

Select all the β-lactam antibiotics.

- Cephalosporins

- Carbepenams

- Monobactam

- Penicillins

The minimum bactericidal concentration is determined by

finding out how many live organisms remain in tubes that showed no growth in an MIC test.

Which of the following pairs about antibiotics is INCORRECT?

Broad-spectrum - an organism that is susceptible to a wide range of medications

Which of the following statements about antibiotic resistance is FALSE?

MRSA is generally resistant to more antibiotics than VRSA.

Please choose the statement that correctly explains how an antibiotic that inhibits protein synthesis can be selective.

Antibiotics bind to the 70S bacterial ribosomes but not to the 80S eukaryotic ribosomes.

(T/F) Some antibiotics fail to kill/inhibit a pathogen simply because the microbe is naturally (intrinsically) resistant to it.

True

What are the advantages of using commercial modifications of conventional susceptibility testing methods?

- They are less labor-intensive.

- They can be automated, which improves speed and data analysis

- Results can be obtained in as few as 4 hours.

Which of the following antimicrobials are used to treat TB (tuberculosis) infections?

- Ethambutol

- Isoniazid

- Pyrazinamide

Identify the two major mechanisms by which microbes can acquire resistance to antimicrobial medications.

- Spontaneous mutation

- Gene transfer

Consider the figure below, which shows MIC results for organism C against antibiotic P. The organism does not grow in the tube containing 16 μg/mL of the antibiotic, and yet it might still be considered resistant to the medication. Why is this so?

It is possible that the maximum safe level of this medication in vivo is less than the MIC, so the antibiotic could not be used at the indicated concentration.

Match the antifungal medications listed with the correct cellular target. Not all labels are used.

Cell division — Griseofulvin

Plasma membrane synthesis and function — Polyenes Azoles Allylamines

Nucleic acid synthesis — Flucytosine

Cell wall synthesis — Echhinocandins

Explain the difference between MIC and MBC.

MIC is the minimum dose of an antimicrobial medication that prevents the growth of an organism, while MBC is the minimum dose of that medication that kills the organism.

Antibiotics that target which of the following would be effective against viruses?

None of the choices is correct.

Which of the following microbes is of growing concern due to increasing resistance to "first-line medications," including isoniazid and rifampin.

Mycobacterium tuberculosis

Identify all the possible adverse effects of using antimicrobials from the choices below.

- Allergic reactions

- Toxic effects at high concentrations

- Suppression of the normal microbiota