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MICRO > Chapter 20 (microbio) > Flashcards

Chapter 20 (microbio) Flashcards

1
Q

One of the earliest researchers to explore the use of chemicals to kill microbial pathogens was

A. Koch.

B. Hooke.

C. Fleming.

D. Ehrlich.

A

D. Ehrlich

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2
Q

The arsenic compound that proved highly effective in treating syphilis was called

A. penicillin.

B. sulfa.

C. erythromycin.

D. Salvarsan.

A

D. Salvarsan.

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3
Q

The first example of an antimicrobial drug synthesized in the laboratory was

A. penicillin.

B. sulfa.

C. erythromycin.

D. Salvarsan.

A

D. Salvarsan.

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4
Q

Prontosil effectively acted on streptococci when the drug was split by enzymes to produce

A. penicillin.

B. sulfanilamide.

C. erythromycin.

D. Salvarsan.

A

B. sulfanilamide.

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5
Q

The use of Salvarsan and Prontosil to treat microbial infections were early examples of

A. antibiotics.

B. toxins.

C. inhibitors.

D. chemotherapy.

A

D. chemotherapy.

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6
Q

Penicillin was discovered by

A. Koch.

B. Hooke.

C. Fleming.

D. Ehrlich.

A

C. Fleming.

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7
Q

The most effective form of penicillin is

A. A.

B. B.

C. E.

D. G.

A

D. G.

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8
Q

One of the earliest antimicrobials isolated from a bacterium was

A. penicillin.

B. ampicillin.

C. Salvarsan.

D. streptomycin.

A

D. streptomycin

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9
Q

Which of the following groups of microorganisms produces antibiotics?

A. Penicillium

B. Streptomyces

C. Bacillus

D. All of the choices are correct.

E. Penicillium AND Streptomyces

A

D. All of the choices are correct.

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10
Q

An antibiotic made by microorganisms and modified by chemists is called

A. anti-metabolic.

B. catabolic.

C. synthetic.

D. semi-synthetic.

A

D. semi-synthetic.

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11
Q

The antimicrobials produced by some molds and bacteria are generally called

A. insecticides.

B. biocides.

C. antiseptics.

D. antibiotics.

A

D. antibiotics.

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12
Q

The toxicity of a given drug is expressed as the

A. selective toxicity.

B. biocide index.

C. biostatic index.

D. therapeutic index.

A

D. therapeutic index.

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13
Q

A high therapeutic index is

A. more toxic to the patient.

B. less toxic to the patient.

C. has no effect on the patient.

D. has no effect on the pathogen.

A

B. less toxic to the patient.

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14
Q

Drugs that are bacteriostatic

A. kill bacteria.

B. promote bacterial growth.

C. inactivate bacterial spores.

D. inhibit the growth of bacteria.

A

D. inhibit the growth of bacteria

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15
Q

Antimicrobials that kill microorganisms have the suffix

A. -cidal.

B. -static.

C. -anti.

D. -genic.

A

A. -cidal.

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16
Q

Antimicrobials that inhibit the growth of microorganisms have the suffix

A. -cidal.

B. -static.

C. -anti.

D. -genic.

A

B. -static.

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17
Q

Antibiotics that affect various strains of Gram-positive bacteria and various strains of Gram-negative bacteria are called

A. isolate usable.

B. stress-induced.

C. narrow-spectrum.

D. broad-spectrum.

A

D. broad-spectrum.

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18
Q

The rate of elimination of an antimicrobial is expressed as its

A. metabolic destructive rate.

B. half-life.

C. effective time.

D. dosage rate.

A

B. half-life.

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19
Q

Antibiotics that are most likely to disrupt the normal flora are termed

A. narrow-spectrum.

B. broad-spectrum.

C. targeted spectrum.

D. semi-synthetic.

A

B. broad-spectrum.

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20
Q

Drugs that are more effective when taken together are called

A. energetic.

B. antagonistic.

C. subtractive.

D. synergistic.

A

D. synergistic.

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21
Q

If drugs are less effective when taken together than when each is taken separately, they are called

A. energetic.

B. antagonistic.

C. additive.

D. synergistic.

A

B. antagonistic.

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22
Q

Antimicrobials may produce

A. allergic reactions.

B. toxic effects.

C. suppression of normal flora.

D. All of the choices are correct.

A

D. All of the choices are correct

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23
Q

Which of the following bacteria have an innate resistance to penicillin?

A. S. aureus

B. S. epidermidis

C. M. luteus

D. Mycoplasma

A

D. Mycoplasma

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24
Q

Which of the following drugs target peptidoglycan?

A. penicillin

B. cephalosporin

C. vancomycin

D. bacitracin

E. All of the choices are correct.

A

E. All of the choices are correct.

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25
Q

All members of the penicillin family have

A. beta-lactam rings.

B. alpha-lactam rings.

C. phenolic rings.

D. sulfanilic rings.

A

A. beta-lactam rings

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26
Q

Penicillin-binding proteins

A. primarily function in the cell to bind to beta-lactam drugs.

B. are enzymes.

C. are involved in cell wall synthesis.

D. inhibit non-growing bacteria.

E. are enzymes AND are involved in cell wall synthesis.

A

E. are enzymes AND are involved in cell wall synthesis.

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27
Q

Beta-lactamases

A. bind to penicillin-binding proteins.

B. bind to peptides.

C. prevent the linking of glycan chains in peptidoglycan.

D. break the beta-lactam ring.

A

D. break the beta-lactam ring

28
Q

The major class(es) of antibiotics that inhibit protein synthesis is/are

A. aminoglycosides.

B. tetracyclines.

C. macrolides.

D. bacitracins.

E. aminoglycosides, tetracyclines AND macrolides.

A

E. aminoglycosides, tetracyclines AND macrolides.

29
Q

Inhibitors of protein synthesis typically key on

A. peptidoglycan precursors.

B. penicillin-binding proteins.

C. ribosomes.

D. porin proteins.

A

C. ribosomes

30
Q

Which is true of aminoglycosides?

A. They are bacteriostatic.

B. They irreversibly bind to the 30S ribosomal subunit.

C. They block peptidoglycan synthesis.

D. They are bactericidal.

E. They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal.

A

E. They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal.

31
Q

Fluoroquinolones typically target

A. ribosomes.

B. penicillin-binding proteins.

C. peptidoglycan.

D. DNA gyrase.

A

D. DNA gyrase.

32
Q

Sulfonamide and trimethoprim are both

A. examples of metabolic inhibitors.

B. folate inhibitors.

C. protein synthesis inhibitors.

D. inhibitors of cell wall synthesis.

E. examples of metabolic inhibitors AND folate inhibitors.

A

E. examples of metabolic inhibitors AND folate inhibitors.

33
Q

Folic acid is ultimately used in the synthesis of

A. topoisomerases.

B. proteins.

C. DNA gyrases.

D. sulfonamides.

E. coenzymes.

A

E. coenzymes.

34
Q

Sulfonamides are similar in structure to

A. DNA gyrases.

B. LPS.

C. ribosomes.

D. PABA.

A

D. PABA

35
Q

Sulfonamides work as

A. competitive inhibitors.

B. noncompetitive inhibitors.

C. ribosome-binding molecules.

D. feedback inhibitors.

A

A. competitive inhibitors.

36
Q

Trimethoprim and sulfonamides have a(n)

A. antagonistic effect.

B. synergistic effect.

C. energetic effect.

D. subtractive.

A

B. synergistic effect.

37
Q

Mycolic acids are targeted by isoniazid in the treatment of

A. S. aureus.

B. S. epidermidis.

C. M. luteus.

D. M. tuberculosis.

A

D. M. tuberculosis.

38
Q

The lowest concentration of a drug that prevents growth of a microorganism is the

A. infectious dose.

B. lethal dose.

C. effective dose.

D. minimum inhibitory concentration.

A

D. minimum inhibitory concentration.

39
Q

The minimum bactericidal concentration is the lowest concentration of a specific antimicrobial drug that kills _______ of a specific type of bacteria.

A. 10%

B. 50%

C. 99.9%

D. 100%

A

C. 99.9%

40
Q

The diffusion bioassay

A. determines the concentration of antimicrobial necessary to kill a bacteria.

B. determines the concentration of antimicrobial necessary to inhibit growth of a bacteria.

C. is similar in principal to the Kirby-Bauer test.

D. determines the concentration of antimicrobial in a fluid.

E. is similar in principal to the Kirby-Bauer test AND determines the concentration of antimicrobial in a fluid.

A

E. is similar in principal to the Kirby-Bauer test AND determines the concentration of antimicrobial in a fluid.

41
Q

Which test is used to determine the susceptibility of a microorganism to an antimicrobial?

A. MIC

B. MIB

C. MLB

D. Kirby-Bauer test

A

D. Kirby-Bauer test

42
Q

The zone size obtained in the Kirby-Bauer test is influenced by the drug’s

A. size.

B. stability.

C. concentration.

D. All of the choices are correct.

A

D. All of the choices are correct

43
Q

A commercial modification of the disk diffusion test is called the

A. A test.

B. B test.

C. C test.

D. D test.

E. E test.

A

E. E test.

44
Q

Bacteria may become antibiotic resistant due to

A. drug-inactivating enzymes.

B. alteration in the target molecule.

C. decreased uptake of the drug.

D. increased elimination of the drug.

E. All of the choices are correct.

A

E. All of the choices are correct.

45
Q

Spontaneous development of resistance to a particular antimicrobial is difficult if the drug

A. binds to several sites on the target molecule.

B. targets several different molecules.

C. affects only one molecule.

D. affects the plasma membrane.

E. binds to several sites on the target molecule AND targets several different molecules.

A

E. binds to several sites on the target molecule AND targets several different molecules

46
Q

The most common method of transfer of antimicrobial resistance is through the use of

A. viruses.

B. R plasmids.

C. introns.

D. exons.

A

B. R plasmids

47
Q

Compliance problems are leading to a large increase in antibiotic resistant strains of

A. Streptococcus.

B. Staphylococcus.

C. Mycobacterium.

D. Pseudomonas.

A

C. Mycobacterium

48
Q

Antiviral drugs may target

A. uncoating.

B. nucleic acid synthesis.

C. viral assembly.

D. viral ribosomes.

E. uncoating, nucleic acid synthesis AND viral assembly.

A

E. uncoating, nucleic acid synthesis AND viral assembly

49
Q

The target of most antifungal drugs is

A. the ribosome.

B. nucleus.

C. cholesterol.

D. ergosterol.

E. cholesterol AND ergosterol.

A

D. ergosterol.

50
Q

The key characteristic of a useful antimicrobial is selective toxicity

A

TRUE

51
Q

Antimicrobials that have a high therapeutic index are less toxic to the patient

A

TRUE

52
Q

Broad-spectrum antibiotics have minimal effect on the normal flora.

A

FALSE

53
Q

Certain antimicrobials may be life-threatening.

A

TRUE

54
Q

Drugs that target peptidoglycan do not affect eukaryotes

A

TRUE

55
Q

Beta-lactam drugs are only effective against growing bacteria.

A

TRUE

56
Q

The MBC may be determined by an extension of the MIC

A

TRUE

57
Q

Antimicrobial resistance can be due to spontaneous mutation or gene acquisition

A

TRUE

58
Q

Viruses are very effectively treated with antibiotics.

A

FALSE

59
Q

Antifungal drugs usually target the cell membrane.

A

TRUE

60
Q

In what clinical situation is it most appropriate to use a broad-spectrum antimicrobial?

A. In an example of a pediatric otitis media (middle ear) infection. We can’t properly test for the specific drug that would best eliminate the infection due to its location, so we use a broad-spectrum drug instead.

B. In a case of viral meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don’t have time to determine which drug will work best, because the patient will die in the meantime.

C. In a case of bacterial meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don’t have time to determine which drug will work best, because the patient will die in the meantime.

D. In a case of Staphylococcus aureus skin infection. Since this microbe can be resistant to several types of drugs, we want to use one that has the broadest spectrum possible to treat this microbe-specific infection.

A

C. In a case of bacterial meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don’t have time to determine which drug will work best, because the patient will die in the meantime.

61
Q

Why would antimicrobials that have toxic side effects be used at all (select the BEST reason)?

A. We want the largest possible number of choices of drugs in case a microbe shows resistance. With more possible weapons (even toxic ones), we have greater ability to eliminate infections.

B. Every person is different. What is toxic to one person may not be toxic to another person. To eliminate a useful drug because it’s toxic to 1% of people treated is a waste.

C. Depending on the location of the infection, we may have no choice but to utilize a drug that has some toxic side effects to the patient.

D. They shouldn’t be used. We have enough of a selection of drugs that we can always select a drug with no toxicity. Drugs with toxicity are simply leftovers-relics from a time when we didn’t have as many drug options.

A

A. We want the largest possible number of choices of drugs in case a microbe shows resistance. With more possible weapons (even toxic ones), we have greater ability to eliminate infections.

62
Q

Why would co-administration of a bacteriostatic drug interfere with the effects of penicillin?

A. Since most bacteriostatic drugs are produced from bacteria, but penicillin is produced from mold, the two drugs are incompatible with each other.

B. A bacteriostatic drug produces interference in the ability of a bacterial cell to take in compounds from the outside environment. Penicillin must be taken in by the cell in order to have its effect, so this would directly inhibit it.

C. Penicillin interferes with cell wall production/stabilization by cross-linking of peptidoglycan. As such, it only works when the cells are actively replicating and MAKING new peptidoglycan. A bacteriostatic drug works by shutting down replication, holding the cells ‘static.’ This would interfere with the mode of action required by the penicillin.

D. The bacteriostatic drugs would bind directly to the penicillin, preventing both its uptake by the cell and its ability to perform its duty within the bacterial cell.

A

C. Penicillin interferes with cell wall production/stabilization by cross-linking of peptidoglycan. As such, it only works when the cells are actively replicating and MAKING new peptidoglycan. A bacteriostatic drug works by shutting down replication, holding the cells ‘static.’ This would interfere with the mode of action required by the penicillin.

63
Q

Why would it be important for the Kirby-Bauer disc diffusion test to use a standard concentration (number of cells in the sample) of each of the bacterial strains being tested?

A. Antibiotics only work within a narrow range of cell concentrations. If you use a concentration that is too low or too high, you will get inaccurate measurements of the zone of inhibition.

B. Antibiotic resistance is usually only manifested by bacteria that have achieved a very high concentration (i.e. they are in the very end of the stationary phase of the growth curve). It’s important to use bacteria specifically at this particular point for disc diffusion testing.

C. If you were to use 1 strain that was in stationary phase (high concentration, replicating very slowly or not at all), and another strain that was just beginning log phase (low concentration but replicating quickly), you could see dramatically different results in the disc diffusion test. This could skew your interpretations of resistance/susceptibility.

D. Growth on the Mueller-Hinton agar plates utilized is very sensitive to the phase of the growth curve the bacteria are in when they are placed on the plate. If they are not in the log phase when they are placed on the plate, they will not grow and the test will be worthless.

A

C. If you were to use 1 strain that was in stationary phase (high concentration, replicating very slowly or not at all), and another strain that was just beginning log phase (low concentration but replicating quickly), you could see dramatically different results in the disc diffusion test. This could skew your interpretations of resistance/susceptibility.

64
Q

Explain how using a combination of two antimicrobial drugs helps prevent the development of spontaneously resistant mutants.

A. All drugs work synergistically with each other-that is, their combined effects are far greater than either could achieve individually. Two drugs together helps to eliminate microbes, even if they have developed spontaneous mutations that would confer upon them resistance to the drugs.

B. It is highly unlikely that the microbe might spontaneously develop 2 specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the 2nd drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall.

C. All drugs work antagonistically with each other-that is, their combined effects are far greater than either could achieve individually. Two drugs together helps to eliminate microbes, even if they have developed spontaneous mutations that would confer upon them resistance to the drugs.

D. Drugs can also select for mutations that will enhance the activity of another drug. So, each of the paired drugs will help to select for spontaneous mutations that enhance the activity of the other drug in the pair.

A

B. It is highly unlikely that the microbe might spontaneously develop 2 specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the 2nd drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall.

65
Q

Why are nucleoside analogs active only against replicating viruses?

A. These drugs can only be taken up by cells that are infected by viruses. They are shut out from non-infected cells. This makes them effective only against cells where viruses are replicating.

B. Each of these drugs is specifically activated by enzymes produced by the viruses. The viruses will only produce these enzymes when they are replicating, so the drugs can only become activated when these processes are occurring.

C. Nucleoside analogs work by directly inhibiting the activity of nucleic acid polymerases. If the virus isn’t actively replicating, there’s no DNA/RNA polymerase active for the drug to inhibit, so the drug cannot work.

D. Nucleoside analogs work by being incorporated into growing strands of DNA/RNA. This indirectly shuts down further extension of these chains. However, new strands of viral DNA/RNA are only being created when the virus is replicating. As such, these drugs can only work when the virus is actively replicating as well.

A

D. Nucleoside analogs work by being incorporated into growing strands of DNA/RNA. This indirectly shuts down further extension of these chains. However, new strands of viral DNA/RNA are only being created when the virus is replicating. As such, these drugs can only work when the virus is actively replicating as well.

MICRO (13 decks)

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