Deck 27: Antimicrobial Therapy

Question 1

Streptogramins are a drug class that possess a synergistic effect. This means that they

A) work best on antibiotic-resistant and antibiotic-intermediate bacteria.
B) kill bacteria using both bacteriostatic and bactericidal mechanisms.
C) have two drug components working together to create a more potent effect.
D) induce an antibody-driven immune response more quickly.
E) kill Gram-negative, Gram-positive, and mycobacteria equally well.

Answer 1

C

Question 2

The best target for development of a new antibiotic would be

A) phospholipids in the plasma membrane.
B) the glycolysis pathway.
C) pyrimidine bases.
D) the nuclear envelope.
E) ribosomes.

Answer 2

E

Question 3

A standardized inoculum of bacteria is used in all microbiology labs when performing a Kirby-Bauer assay. This standard allows for a visual turbidity reading to achieve reproducibility in the number of bacteria inoculated on a plate. This is most important because

A) multiple antibiotics testing requires that bacteria be spread evenly around the plate.
B) the MIC value can only be achieved by serial dilutions.
C) the number of organisms placed on an agar surface is inversely proportional to the size of the zone of inhibition.
D) bacterial counts need to be the same across all labs, since incubation times can differ.
E) bacterial counts need to be the same across all labs, since plate sizes in this assay can differ.

Answer 3

C

Question 4

Minimal inhibitory concentration, or MIC, is ________ concentration of a drug that will prevent the growth of an organism.

A) the average
B) the lowest
C) the highest
D) the midline
E) any

Question 5

A drug designed to poke holes into the plasma membrane of a Pseudomonas aeruginosa bacteria would best be considered

A) bactericidal.
B) microbe sensitive.
C) semiselective.
D) bacteriostatic.
E) bacteriocompetent.

Question 6

If a drug were designed that only seemed to affect the growth of Burkholderia pseudomallei, this drug would be considered ________ range.

A) broad
B) uni-narrow
C) slightly narrow
D) extremely narrow
E) species-sensitive

Question 7

Which virus is NOT effected by antiviral DNA synthesis inhibitors?

A) influenza
B) HIV
C) H1N1
D) Ebola
E) Marburg

Question 8

The Mueller-Hinton medium used in the Kirby-Bauer assay contains no para-aminobenzoic acid (PABA, normally found in most media) because it

A) causes an increase in bacterial lag time.
B) interferes with the diffusion of penicillin and penicillin-like drugs.
C) creates a false bacteriostatic effect.
D) polymerizes streptomycin drugs and their derivatives.
E) inhibits sulfa antibiotics testing.

Question 9

An example of an antibiotic that binds to the 30S ribosomal subunit would be

A) streptogramins.
B) macrolides.
C) beta-lactams.
D) fluoroquinolones.
E) aminoglycosides.

Question 10

A newly isolated antibiotic that kills Klebsiella sp. was found in soil bacteria. Chemical analysis showed the structure of this molecule to contain a cysteine/valine ring structure. This new antibiotic would be classified as a ________ inhibitor.

A) metabolic
B) cell membrane
C) protein-synthesis
D) DNA synthesis
E) cell wall

Question 11

An MIC test can determine all of the following EXCEPT

A) the lowest level of an antibiotic that kills a particular bacteria.
B) the highest level of an antibiotic that kills a particular bacteria.
C) levels of an antibiotic that do not kill a particular bacteria.
D) drug susceptibility and resistance.
E) whether the drug is bacteriostatic or bactericidal.

Question 12

Bacterial peptidoglycan formation uses all of the following components EXCEPT

A) N-acetylmuramic acid.
B) uridine diphosphate.
C) bactoprenol.
D) hopanoid.
E) N-acetylglucosamine.

Question 13

Sometimes, systemic mycoses require more aggressive treatment. A drug used in this treatment is

A) amphotericin B.
B) penicillin.
C) lamisil.
D) tetracycline.
E) penicillin.

Question 14

Salvarsan is an arsenical compound used to target the pathogen

A) Treponema pallidum.
B) Plasmodium falciparium.
C) Escherichia coli.
D) Streptococcus mutans.
E) Mycobacterium tuberculosis.

Question 15

Bactericidal antibiotics include all of the following EXCEPT

A) aminoglycosides.
B) rifampin.
C) macrolides.
D) subcutaneous isoniazidchloramphenicol.
E) quinolones.

Question 16

Consider an MIC result of 10 mg of penicillin for bacterial strain A, 15 mg for stain B, 18 mg for strain C, and 27 mg of penicillin for strain D. It can be interpreted that bacterial strain ________ is more susceptible to penicillin than the others.

A) A
B) B
C) C
D) D
E) All strains are equally susceptible.

Question 17

Which of the following statements about the Kirby-Bauer assay is true?

A) It is used to test multiple bacteria simultaneously on a single plate.
B) It uses serial dilutions of specific antibiotics to determine MIC.
C) Zones of inhibition that are smaller are better antibiotics than antibiotics that form larger zones.
D) It can test up to 12 different antibiotic disks at one time.
E) It cannot be correlated with in vivo tissue concentrations.

Question 18

Why does the structure of gramicidin, shown below, only allow topical use as an antibiotic?

A) synthesis of nucleic acid
B) synthesis of cell wall
C) beta lactam rings
D) DNA synthesis
E) It creates channels in cell membranes.

Question 19

A bacterium may be penicillin resistant due to all of the following EXCEPT

A) a Gram-negative cell wall.
B) beta-lactase production.
C) a Gram-positive cell wall.
D) modified transpeptidases.
E) modified transglycosylases.

Question 20

The bacteria killed in Alexander Fleming's experiment during his discovery of penicillin were

A) Pseudomonas aeruginosa.
B) Escherichia coli.
C) Staphylococcus aureas.
D) Streptococcus pyogenes.
E) Klebsiella pneumonia.

Question 21

Chemical synthesis of a new drug with a 15-member lactone ring structure would be predicted to be most similar to the antibiotic class ________ and the ________ inhibitor.

A) gramicidin; membrane
B) nalidixic acid; DNA
C) actinomycin D; RNA synthesis
D) tetracyclines; 30S
E) macrolides; 50S

Question 22

What is shown in the figure below?

A) B-lactam
B) streptogramins
C) protein synthesis inhibitors
D) ribosome
E) mulidrug resistance efflux pump

Question 23

A bacterium has evolved a new enzyme that can cleave a beta-lactam ring structure. It would NOT be treatable by which class of drugs?

A) aminoglycosides
B) ampicillin
C) tetracycline
D) bacitracin
E) quinolones

Question 24

Gene-expression elements that account for rapid transmission of drug resistance due to their mobility and ability to collect resistance gene cassettes are called

A) mobile units.
B) virulence plasmids.
C) integrons.
D) insertion prophages.
E) multidrug resistant enhancers.

Question 25

One of the leading sources of human infection by antibiotic-resistant organisms is ________ infections.

A) farm animal
B) locker room
C) dental surgery
D) nosocomial
E) food recall

Question 26

One way a macrolide-producing organism, such as Streptomyces sp., prevents its own demise from production of the antibiotic is to

A) methylate its own RNA.
B) change its peptidoglycan linkages.
C) create an MDR pump.
D) change its DNA structure.
E) only produce the antibiotic during the death phase.

Question 27

A newly identified genomic target for treating penicillin-resistant Streptococcus pneumoniae is the

A) CaPS: capsular polysaccharides.
B) Ply: pneumolysin toxin.
C) MotB: flagella protein.
D) PGRP: peptidoglycan recognition protein.
E) CbpG: pneumococcal adhesin protein.

Question 28

What does the figure below represent?

A) amphotericin B
B) clotrimazole
C) nystatin
D) penicillin
E) cephalosporin

Question 29

The multidrug resistance, or MDR, efflux pumps found in organisms such as resistant strains of Escherichia coli work most similarly to

A) ABC transporters.
B) facilitated diffusion.
C) reverse osmosis.
D) electron transport.
E) phospholipid flip-flop.

Question 30

A persister cell is an unsolved mystery of microbiology because these cells

A) grow rapidly in the presence of antibiotics.
B) neither grow nor die in the presence of an antibiotic.
C) cannot exit log phase growth when placed in an optimum antibiotic niche.
D) can form neither individual cells nor biofilms.
E) cycle between animal and human populations, never dying out.

Question 31

Which of the following would NOT be a way that a Pseudomonas aeruginosa bacteria could inherit resistance genes from other bacteria?

A) transposons
B) random mutation
C) prophages
D) plasmid integration
E) integrons

Question 32

Which of the following is a clinically important lung bacteria that kills approximately 2 million people annually and is becoming increasingly multidrug resistant?

A) Streptococcus pneumoniae
B) Staphylococcus aureas
C) Mycobacterium tuberculosis
D) Escherichia coli
E) Plasmodium falciparum

Question 33

Bactrim, a sulfa drug used to treat urinary tract infections, does NOT harm host cells because eukaryotic cells

A) have efflux pumps for the drug.
B) take in folic acid in the diet.
C) do not transport the drug into the cell.
D) are naturally immunized from the drug.
E) make their own PABA precursors.

Question 34

A bacterial strain exhibiting a DNA gyrase mutation would most likely inhibit the activity of what class of antibiotics?

A) metronidazoles
B) tetracyclines
C) quinolones
D) cephalosporins
E) sulfa drugs

Question 35

A bacterial strain exhibiting a unique RNA polymerase structure would most likely inhibit the activity of which antibiotic?

A) rifampin
B) nalidixic acid
C) penicillin
D) streptomycin
E) chloramphenicol

Question 36

A negative structural mutation in the norA gene in Staphylococcus aureus could have the effect of

A) decreased protein synthesis.
B) increased bacterial conjugation.
C) decreased drug resistance.
D) increased uptake of beta-lactams.
E) decreased rate of clonal division.

Question 37

Aicrobes that produce antibiotic molecules ________ as a way to prevent self destruction.

A) pump the antibiotic out
B) modify the target so it cannot bind
C) add modifying groups to the antibiotic
D) destroy the antibiotic
E) There is no need to avoid self-destruction.

Question 38

What microbe would you grow if you wanted to prepare and isolate some vancomycin?

A) Amycolatopsis orientalis
B) Staphylococcus aureas
C) Veillonella parvula
D) Streptomyces garyphalus
E) Bacillus subtilis

Question 39

Which of the following would NOT be considered a way to fight bacterial resistance?

A) creating molecules without antibiotic activity that can compete and bind antibiotic-resistance enzymes
B) increase the amount of antibiotics in our foods to prevent food-borne infection
C) alter the structure of antibiotics to sterically hinder the binding of antibiotic-resistance enzymes
D) link different antibiotics together, forming hybrid antibiotics with dual action and targets
E) administer antibiotics more prudently when possible

Question 40

A possible effective treatment for a patient who comes into a medical office with tuberculosis has been derived from

A) Penicillium notatum.
B) Amycolatopsis orientalis.
C) Staphylococcus aureas.
D) Streptomyces garyphalus.
E) Bacillus subtilis.

Question 41

A new antibiotic, platensimycin, was recently discovered from what organism?

A) Bacillus subtilis
B) Bacillus thuringiensis
C) Escherichia platentis
D) Streptomyces platensis
E) Klebsiella pneumoniae

Question 42

Which of the following is an antiviral that inhibits DNA synthesis?

A) Acyclovir
B) Amantadine
C) Zanamivir
D) Ribavirin
E) Raltegravir

Question 43

Antiviral therapy for the human immunodeficiency virus (HIV) usually consists of a protease inhibitor that inhibits what function?

A) viral exit of the newly formed virions by vial budding
B) viral fusion of the viral envelope with the host cell membrane
C) binding to the CD4 receptor on human immune cells
D) insertion of viral DNA into the host cell DNA
E) cleavage of polypeptide chains to make functional HIV viral proteins

Question 44

A novel antibiotic, discovered to treat blood-borne bacteria during sepsis infection, is found to have a dramatic effect during MIC assays. Mice studies that followed found the drug to be cleared from the body within 15 minutes of oral administration. Would this be a good drug candidate for sepsis? Why or why not? What suggestions would you make? Support your answer.

Question 45

The influenza envelope neuraminidase viral spike protein allows the virus to

A) escape from antibiotics.
B) acidify the endocytic chamber.
C) release new virions from an infected host cell.
D) bind to host cell glycoproteins.
E) undergo viral membrane fusion.

Question 46

Bactericidal antibiotics include all of the following EXCEPT

A) aminoglycosides.
B) quinolones.
C) rifampins.
D) macrolides.
E) penicillins.

Question 47

Most antiviral drugs approved for clinical use target viral proteins. Which of the following is NOT a targeted viral protein?

A) Cap-binding complex
B) proteases
C) polymerases
D) entry proteins
E) alpha-glucosidase

Question 48

A patient suffering from a systemic mycosis with aspergillosis would best be served by which antifungal?

A) imidazole
B) lamisil
C) nystatin
D) amphotericin B
E) griseofulvin

Question 49

There are fewer antivirals currently available in most pharmacies than there are antibacterials because

A) bacterial cells are less complex than viruses.
B) selective toxicity is much easier to achieve for bacteria.
C) most antivirals available are for uncommon, life-threatening infections.
D) selective toxicity is much easier to achieve for viruses.
E) MIC values are larger for bacteria than for viruses.

Question 50

Compare and contrast the utility of the antibiotic polymyxin versus cephalosporin in clearing up an Escherichia coli skin infection that has become systemic.

Question 51

Summarize what is occurring in the figure below.

Question 52

Platensimycin is a novel antibiotic that was recently discovered. An attribute it does NOT have is that it

A) is bacteriostatic.
B) binds FabF protein found in fatty acid biosynthesis.
C) has a broad spectrum of activity.
D) works on both Gram-negative and Gram-positive bacteria.
E) targets the bacterial translation of proteins.

Question 53

Antiviral therapy for the human immunodeficiency virus (HIV) usually consists of ________ or more different ________ inhibitors to prevent resistance.

A) five; nonnucleoside reverse transcriptase
B) three; nucleoside reverse transcriptase
C) four; integrase
D) two; protease
E) two; nucleoside, nonnucleoside, and protease

Question 54

What is NOT a novel idea for new antibiotic drug development?

A) interfering with quorum-sensing mechanisms
B) "corking" the type II secretion apparatus
C) use of photosensitive chemicals to generate reactive oxygen species
D) chemical modification of beta-lactams
E) use of nanotubes to poke holes in bacterial membranes

Question 55

The antiviral nucleoside inhibitor zidovudine, used in treating HIV infection, works by

A) fooling reverse transcriptase to incorporate it, causing a chain termination reaction.
B) disabling protease and preventing HIV protein folding.
C) blocking gag and pol genes from transcription.
D) binding directly to reverse transcriptase and allosterically inactivating the enzyme.
E) sterically hindering integrase from cutting into the host nuclear DNA.

Question 56

Why is it that the organism that produces penicillin, Penicillin notatum, is not affected by the production of this molecule, but Staphylococcus aureus is? Of what benefit is the antibiotic in the organism that created it?

Question 57

Summarize how infection is cleared from the body of a patient who has been prescribed antibiotics that are bacteriostatic. Give one example of a bacteriostatic antibiotic in your answer.

Question 58

What is the definition of "antibiotic"? Where are antibiotics isolated from, and why are these compounds made in nature?

Question 59

In the 1930s, Gerhard Domagk injected his own daughter with a red dye in hopes of curing her invasive streptococcal infection, even though testing of this agent on agar plates growing Streptococcus sp. showed no antimicrobial effect. Analyze why he did this. What did this study show the importance of?

Question 60

A molecular microbiologist identified a unique sequence of DNA causing an amino acid shift mutation within the gene encoding for peptidoglycan transpeptidase in a clinical strain of Streptococcus pneumoniae. Summarize what this molecule does and hypothesize what benefit it could have to an organism.

Question 61

Why is metronidazole uneffective against an aerobic bacteria like Staphylococcus aureas?

Question 62

Why is the newly discovered antibiotic class called pyronins considered to be a class of antibiotics that will be hard for a bacteria to become resistant to?

Question 63

If a Staphylococcus aureas bacterium was to become resistant to a newly discovered antibiotic, what are the four basic forms of resistance this bacterium could have acquired?

Question 64

You are designing a new antibiotic to treat infections caused by the fungal agent Cryptococcus neoformans, a potentially fatal lung infection in patients on long-term corticosteroid therapy. What issues could you run into with selective toxicity, and what strategies would you use in your development?

Question 65

How have modern agricultural practices contributed to the increase of antibiotic resistance seen today?

Question 66

Outline and discuss the steps that a research laboratory would go through to discover a new antibiotic to treat a systemic infection with methicillin-resistant Staphylococcus aureus (MRSA).

Question 67

Explain the activation of metronidazole using the figure below.

Question 68

How does prescribing a "dummy compound," like clavulanic acid, begin to address an infant bacterial infection with a Klebsiella sp. that is ampicillin resistant?

Question 69

Several antifungal therapeutic agents act to inhibit sterol synthesis. Explain why this does NOT affect mammalian systems.

Question 70

Describe the mechanism by which the influenza virus enters or exits a host cell and one potential drug target that is being used to prevent infection.

Question 71

How does saving the rain forest (and other endangered habitats) correlate with the fight to prevent human morbidity and mortality caused by bacterial disease? Give an example to support your argument.

Question 72

Why are drug-resistant bacteria less viable in comparison with wild type?