Microbiology, Ch 20, Nester's 9th

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The antimicrobials produced by some molds and bacteria are generally called: insecticides. biocides. antiseptics. antibiotics.

antibiotics. Molds and bacteria can produce antibiotics. - antibiotics - antimicrobial medications naturally produced by microorganisms.

Trimethoprim and sulfonamides have a(n): antagonistic effect. synergistic effect. energetic effect. subtractive.

synergistic effect.

Which of the following drugs target peptidoglycan? a. penicillin b. cephalosporin c. vancomycin d. bacitracin e. All of the choices are correct.

e. All of the choices are correct.

The most effective form of penicillin is: penicillium. penicillin G. penicillin E. penicillin A. penicillin B.

penicillin G.

The minimum bactericidal concentration is the lowest concentration of a specific antimicrobial drug that kills _______ of a specific type of bacteria. 10% 50% 99.9% 100%

99.9%

T/F - In 1928, Alexander Fleming observed that the growth of the bacterium Staphylococcus aureus was inhibited by a mold thereby discovering the first antibiotic.

True

T/F - The MBC may be determined by an extension of the MIC.

True

T/F - The key characteristic of a useful antimicrobial is selective toxicity.

True

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

True

Which is the correct definition of selective toxicity? - A medication that only targets Gram-negative bacteria. - The lowest dose of a medication toxic to the pathogen. - A medication causing greater harm to a pathogen than to the host. - A medication causing greater harm to a host than to a pathogen. - The range between the therapeutic dose and the toxic dose of a medication.

- A medication causing greater harm to a pathogen than to the host. That last one is the therapeutic window.

Why are some drugs that inhibit protein synthesis in bacteria also harmful to humans? - Some drugs are powerful enough to inhibit human cell protein synthesis as well as that of bacterial cells. - Humans and bacteria have very similar types of ribosomes. - Some human cells have mutated ribosomes, which are more susceptible to these drugs. - Eukaryotic mitochondria have 70S ribosomes

- Eukaryotic mitochondria have 70S ribosomes

Which of the following is not used for treating bacterial infections? - Griseofulvin - Methicillin - Rifampin - Tetracycline - Ampicillin

- Griseofulvin

Acyclovir is a: a) nucleoside analog b) non-nuceoside polymerase inhibitor c) protease inhibitor d) none of the above

a) nucleoside analog

Please choose the class of antimicrobials that would have the most selective toxicity. A. Antimicrobials that inhibit cell wall synthesis B. Antimicrobials that interfere with nucleic acid structure and function C. Antimicrobials that interfere with cell membrane structure and function D. Antimicrobials that inhibit protein synthesis

A. Antimicrobials that inhibit cell wall synthesis

A. The group of antimicrobial medications that inhibit peptidoglycan synthesis and have a shared chemical structure called a β-lactam ring. B. The administration of two or more antimicrobial medications simultaneously to prevent the growth of mutants that might be resistant to one of the antimicrobials C. The resistance of an organism to an antimicrobial due to the inherent characteristics of that type of organism D. An antimicrobial able to inhibit or kill a wide range of microorganisms, often including both Gram-positive and Gram-negative bacteria E. A transporter that moves molecules out of the cell

A. Beta (β)-lactam drugs B. combination therapy C. intrinsic, innate resistance D. Broad-spectrum antimicrobial E. efflux pump

A. The lowest concentration of a specific antimicrobial medication that prevents growth of a given microbial strain in vitro B. An antimicrobial medication that inhibits or kills a limited range of bacteria C. The procedure used to determine bacterial susceptibility to concentrations of an antimicrobial medication usually present in the bloodstream of an individual receiving the drug D. The target of β-lactam antimicrobial medications and heavy metals E. Strains of Staphylococcus aureus that are resistant to methicillin

A. Minimum Inhibitory Concentration, MIC B. Narrow-spectrum antimicrobial C. Kirby-Bauer disc diffusion assay D. Penicillin-binding proteins, PBP E. MRSA S. aureus

Multiple-drug resistant microbes: a. are resistant to all antimicrobial agents b. respond to new antimicrobials by developing resistance c. frequently develop in hospitals d. all of the above

c. frequently develop in hospitals

Staphylococcus aureus strains referred to as HA-MRSA are sensitive to: a) methicillin b) penicillin c) most cephalosporins d) vancomycin e) none of the above

d) vancomycin

Which of the following microbes, a leading cause of pneumonia in the United States, is of growing concern due to increased resistance to penicillin? A. Staphylococcus aureus B. Streptococcus pneumoniae C. Enterobacteriaceae D. Mycobacterium tuberculosis E. Mycoplasma pneumoniae

B. Streptococcus pneumoniae

Gonorrhea is a sexually transmitted infection (STI) caused by the diplococcus Neisseria gonorrhoeae, commonly called gonococcus (GC). This organism developed resistance to penicillin and tetracycline in the 1980s, after which fluoroquinolones were the recommended drugs for treating GC. Subsequent resistance to the fluoroquinolones has led to the current recommended treatment of injected ceftriaxone in combination with oral azithromycin. Although this approach continues to be effective, recent data from the CDC indicates that resistance to azithromycin is emerging. Azithromycin is a bacteriostatic antibiotic that interferes with protein synthesis. Ceftriaxone is a β-lactam antibiotic and is primarily bactericidal. This means that: A) azithromycin kills bacterial cells while ceftriaxone inhibits the growth of bacterial cells. B) bacteria are sensitive to azithromycin but are resistant to ceftriaxone. C) azithromycin inhibits the growth of bacterial cells while ceftriaxone kills bacterial cells. D) bacteria are resistant to azithromycin but are susceptible to ceftriaxone. E) azithromycin can only be used against Gram-positive bacteria.

C) azithromycin inhibits the growth of bacterial cells while ceftriaxone kills bacterial cells.

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) broad-spectrum. D) narrow-spectrum. E) intermediate.

C) broad-spectrum. slide 14

C) it contains a nucleotide analog and a sugar.

One of the earliest antimicrobials isolated from a bacterium was: penicillin. ampicillin. Salvarsan. streptomycin.

streptomycin. Waksman isolated a bacterium from soil, Streptomyces griseus, that produced an antibiotic he called streptomycin - antibiotic (naturally produced antimicrobial) Molds and bacteria can produce antibiotics. - (Fleming) penicillin from a mold, ampicillin - a penicillin derivative, Salvarsan (arsphenamine) is an arsenic compound (Ehrlich)

The toxicity of a given drug is expressed as the: selective toxicity. biocide index. biostatic index. therapeutic index.

therapeutic index TI = toxic dose/therapeutic dose - higher is better - means a larger difference between toxic and therapeutic dose (larger therapeutic window)

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.

e. All of the choices are correct.

Which of the following groups of microorganisms produces antibiotics? a. Penicillium b. Streptomyces c. Bacillus d. Penicillium AND Streptomyces e. All of the choices are correct.

e. All of the choices are correct. p.501 - Most antibiotics come from microorganisms that normally live in the soil, including species of Streptomyces and Bacillus (bacteria), and Penicillium and Cephalosporium (fungi).

Beta-lactamases: a. bind to penicillin-binding proteins. b. bind to peptides. c. prevent the linking of glycan d. chains in peptidoglycan. e. break the beta-lactam ring.

e. break the beta-lactam ring.

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.

e. examples of metabolic inhibitors AND folate inhibitors. animal cells can't make folate, we have to supplement it.

Please select the FALSE statement regarding antibiotic resistance. - Changes in the porin proteins can prevent certain antimicrobials from entering a cell's periplasm or cytoplasm. - The bacterial enzyme chloramphenicol acetyltransferase confers resistance to the penicillins. - Modifications in the penicillin-binding proteins (PBPs) prevent β-lactam antibiotics from binding to them. - Some antibiotic-inactivating enzymes have an extended spectrum and confer resistance to a wide variety of antibiotics. - Bacteria that produce efflux pumps sometimes become resistant to several different antimicrobials simultaneously.

- The bacterial enzyme chloramphenicol acetyltransferase confers resistance to the penicillins.

All of the following are mechanisms of action associated with drugs that inhibit cell wall synthesis except __________. - dismantling existing peptidoglycan molecules - blocking the secretion of NAG and NAM from the cytoplasm - preventing crosslinking between NAM subunits - interfering with the formation of alanine-alanine crossbridges

- dismantling existing peptidoglycan molecules

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) If you were to use one strain that was 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 different results in the test, affecting your interpretation. B) 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. C) Antibiotic resistance is usually only manifested by bacteria that have achieved a very high concentration. It's important to use bacteria specifically at this particular point for disc diffusion testing. D) 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. E) Bacteria only develop resistance when there are more than 1012 cells/ mL. If resistance is to be detected, the test must use at least this concentration of cells. If fewer cells are used, no zone of inhibition will develop.

A) If you were to use one strain that was 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 different results in the test, affecting your interpretation.

A) Peptidoglycan synthesis I admit that I don't understand the wording of this question.

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 from a time when we didn't have as many drug options. E) These are all reasons to use antimicrobials that have a low therapeutic index.

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.

Gonorrhea is a sexually transmitted infection (STI) caused by the diplococcus Neisseria gonorrhoeae, commonly called gonococcus (GC). This organism developed resistance to penicillin and tetracycline in the 1980s, after which fluoroquinolones were the recommended drugs for treating GC. Subsequent resistance to the fluoroquinolones has led to the current recommended treatment of injected ceftriaxone in combination with oral azithromycin. Although this approach continues to be effective, recent data from the CDC indicates that resistance to azithromycin is emerging. Fluoroquinolones act by inhibiting DNA gyrase, an enzyme involved in DNA replication. Resistance to this antibiotic is most commonly by: A) a change in the DNA gyrase target, an example of acquired resistance. B) enzymatic modification of the ribosomal target, an example of innate resistance. C) a change in the DNA gyrase target, an example of innate resistance. D) due to a mutation in the gene that encodes RNA polymerase, an example of adaptive resistance. E) increased efflux of the drug from the target cell, an example of innate resistance.

A) a change in the DNA gyrase target, an example of acquired resistance.

The major class(es) of antibiotics that inhibit protein synthesis include all of the following EXCEPT: A) bacitracins. B) aminoglycosides. C) tetracyclines. D) macrolides. E) streptogramins.

A) bacitracins. Bacitracins mess will cell wall synthesis.

An elderly patient comes to see you complaining of a very painful rash. When he lifts his shirt, you see that he has a rash of small blisters (vesicles) on one side of his back. You think he likely has shingles, caused by varicella-zoster virus (VZV), a double-stranded DNA virus that belongs to the Herpesviridae family. You explain this to your patient, who asks you to please give him an antibiotic for his infection. You tell him an antibiotic will not help him, and give him information on virus infections and their treatment. Acyclovir is selective and low in toxicity, causing little harm to uninfected cells, because: A) only a virally encoded enzyme can convert the medication into its active form (from nucleoside analog to nucleotide analog). B) only a virally encoded enzyme can convert the medication into its active form (from nucleotide analog to nucleoside analog). C) viral DNA is structurally very different from cellular DNA. D) host cells have the ability to repair the damage caused by nucleotide analogs. E) host cells have an enzyme that prevents the conversion of the medication into its active form.

A) only a virally encoded enzyme can convert the medication into its active form (from nucleoside analog to nucleotide analog).

Gonorrhea is a sexually transmitted infection (STI) caused by the diplococcus Neisseria gonorrhoeae, commonly called gonococcus (GC). This organism developed resistance to penicillin and tetracycline in the 1980s, after which fluoroquinolones were the recommended drugs for treating GC. Subsequent resistance to the fluoroquinolones has led to the current recommended treatment of injected ceftriaxone in combination with oral azithromycin. Although this approach continues to be effective, recent data from the CDC indicates that resistance to azithromycin is emerging. The situation in which the effect of two antimcrobials given together is more effective than the effect of either medication given individually is referred to as: A) synergism. B) antagonism. C) nihilism. D) symbiosis. E) dysbiosis. Correct answer: A

A) synergism.

A. The development of antimicrobial resistances through spontaneous mutation or acquisition of new genetic information B. A chemical produced by certain molds and bacteria that kills or inhibits the growth of other organisms C. A chemical used to treat microbial infections; also called antimicrobial D. Plasmids that encode resistance to one or more antimicrobial medications and heavy metals E. A measure of the relative toxicity of a medication, defined as the ratio of minimum toxic dose to minimum effective dose F. Enzyme that breaks the β-lactam ring of a β-lactam drug, thereby inactivating the medication

A. Acquired Resistance B. Antibiotic C. Antimicrobial drug D. R plasmids E. Therapeutic index F. beta-lactamase

Please select the FALSE statement regarding tissue distribution, metabolism, and excretion of medications. A) Patients who have liver dysfunction often metabolize medications more slowly, so their doses must be adjusted to avoid toxic levels. B) The half-life of a medication is the time it takes for the serum concentration of that chemical to decrease by 100%. C) Medications that are unstable at low pH are typically given by intravenous or intramuscular injection. D) A medication with a half-life of over 24 hours is taken only once a day or less. E) A medication that has a very short half-life usually needs to be taken several times a day.

B) The half-life of a medication is the time it takes for the serum concentration of that chemical to decrease by 100%. - it's by 50%

If drugs are less effective when taken together than when each is taken separately, they are: A) energetic. B) antagonistic. C) additive. D) synergistic. E) commensal.

B) antagonistic. Not synergistic and not antagonistic then it's additive. You get the effects of both just added, not more like in synergistic or less like in antagonistic. slide 15

Gonorrhea is a sexually transmitted infection (STI) caused by the diplococcus Neisseria gonorrhoeae, commonly called gonococcus (GC). This organism developed resistance to penicillin and tetracycline in the 1980s, after which fluoroquinolones were the recommended drugs for treating GC. Subsequent resistance to the fluoroquinolones has led to the current recommended treatment of injected ceftriaxone in combination with oral azithromycin. Although this approach continues to be effective, recent data from the CDC indicates that resistance to azithromycin is emerging. Initially, GC was treated with penicillin, which targets ________, and tetracycline which targets ________. A) protein synthesis; peptidoglycan synthesis B) peptidoglycan synthesis; protein synthesis C) protein synthesis; capsule formation D) capsule formation; ergesterol formation E) cell membrane integrity; folic acid synthesis

B) peptidoglycan synthesis; protein synthesis

B) viral nucleic acid synthesis.

In what clinical situation is it most appropriate to use a broad-spectrum antimicrobial? A) In an example of a viral 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. E) There are no appropriate situations for using broad-spectrum antibiotics, because they almost always lead to resistance. It is much better to use a narrow-spectrum medication.

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. Use a broad spectrum antimicrobial in acute, life-threatening cases when there is no time for a C&S (then do one and switch to a narrow spectrum if needed).

Explain the difference between MIC and MBC. A .MBC is the maximum dose of an antimicrobial medication needed to prevent the growth of an organism, while MIC is the maximum dose of that medication needed to kill the organism. B. MBC is the minimum dose of an antimicrobial medication that prevents the growth of an organism, while MIC is the minimum dose of that medication that kills the organism. C. 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. D. MIC is the maximum dose of an antimicrobial medication needed to prevent the growth of an organism, while MBC is the maximum dose of that medication needed to kill the organism.

C. 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.

Which of the following statements concerning development of antibiotic resistance is FALSE? A. It is often mediated by R-plasmids. B. Resistant cells are normally in the minority in a bacterial population. C. Resistant cells grow more efficiently and quickly than susceptible cells. D. New resistance genes can be gained through transformation, transduction, or conjugation. E. Resistance can occur through mutation of existing bacterial genes.

C. Resistant cells grow more efficiently and quickly than susceptible cells.

Which of the following is NOT a criterion by which all antimicrobial agents can be evaluated? A. their spectrum of action B. their efficacy C. their activity against cell walls D. their route of administration E. their safety

C. their activity against cell walls

Please select the TRUE statement regarding bacterial resistance to antimicrobials. A) Gram-positive bacteria are intrinsically resistant to certain medications because the lipid bilayer of their outer membrane prevents the molecules from entering. B) Intrinsic resistance generally occurs through spontaneous mutation or horizontal gene transfer. C) The genes for antimicrobial resistance are often carried on fertility plasmids (F plasmids). D) Mycoplasma species lack a cell wall, so they are resistant to penicillin that interferes with peptidoglycan synthesis. This is an example of intrinsic resistance. E) Acquired resistance is very limited because microorganisms cannot evolve, so are incapable of developing mechanisms to avoid the effects of medications.

D) Mycoplasma species lack a cell wall, so they are resistant to penicillin that interferes with peptidoglycan synthesis. This is an example of intrinsic resistance. A. G- have outer membrane, not G+ B. Acquired resistance, intrinsic is something they have, not something they get by mutation or transfer. C. R plasmids, not F. E. Just no.

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 interferes with 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) 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. D) Penicillin interferes with cell wall production so 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. E) Nothing interferes with the effects of penicillin. It is the most effective medication that we have, so is never used with the addition of a second drug when treating a person.

D) Penicillin interferes with cell wall production so 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.

An elderly patient comes to see you complaining of a very painful rash. When he lifts his shirt, you see that he has a rash of small blisters (vesicles) on one side of his back. You think he likely has shingles, caused by varicella-zoster virus (VZV), a double-stranded DNA virus that belongs to the Herpesviridae family. You explain this to your patient, who asks you to please give him an antibiotic for his infection. You tell him an antibiotic will not help him, and give him information on virus infections and their treatment. Viruses are completely unaffected by antibiotics because: A) they rely almost completely on the host cell's metabolic machinery for their replication, making it difficult to find a target for selective toxicity. B) they have no cell wall, ribosomes, or any other structure targeted by antibiotics. C) they rely almost completely on the host cell's metabolic machinery for their replication, making it difficult to find a target for selective toxicity AND most viruses are innately resistant to broad- and narrow-spectrum antibiotics. D) They have no cell wall, ribosomes, or any other structure targeted by antibiotics AND they rely almost completely on the host cell's metabolic machinery for their replication, making it difficult to find a target for selective toxicity. E) most viruses are innately resistant to broad- and narrow-spectrum antibiotics.

D) They have no cell wall, ribosomes, or any other structure targeted by antibiotics AND they rely almost completely on the host cell's metabolic machinery for their replication, making it difficult to find a target for selective toxicity.

The target of most antifungal drugs is: A) the ribosome AND the cytoplasmic membrane. B) the nucleus AND mitochondria. C) cholesterol. D) ergosterol. E) cholesterol AND ergosterol.

D) ergosterol.

Gonorrhea is a sexually transmitted infection (STI) caused by the diplococcus Neisseria gonorrhoeae, commonly called gonococcus (GC). This organism developed resistance to penicillin and tetracycline in the 1980s, after which fluoroquinolones were the recommended drugs for treating GC. Subsequent resistance to the fluoroquinolones has led to the current recommended treatment of injected ceftriaxone in combination with oral azithromycin. Although this approach continues to be effective, recent data from the CDC indicates that resistance to azithromycin is emerging. Penicillin is a(n): A) β-lactam antibiotic and has a low therapeutic index, meaning that it is of high toxicity to the host. B) carbapenam and is thus resistant to extended spectrum β-lactamases. C) glycopeptide antibiotic and is thus used as an antibiotic of last resort. D) β-lactam antibiotic and has a high therapeutic index, meaning that it is of low toxicity to the host. E) aminoglycoside and may sometimes cause kidney damage.

D) β-lactam antibiotic and has a high therapeutic index, meaning that it is of low toxicity to the host.

Which of the following pairs is INCORRECT? A. Therapeutic index - measure of the relative toxicity of a medication B. Short half-life - medication needs to be taken relatively frequently C. 70S ribosome - target of some antibacterial medications D. Broad spectrum - an organism that is susceptible to a wide range of medications E. Bacteriostatic - inhibits growth of bacteria

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

The E test determines which of the following? A. susceptibility B. MBC C. MIC D. both susceptibility and MIC E. both MBC and MIC

D. both susceptibility and MIC

Which of the following drugs specifically targets cell walls that contain arabinogalactan-mycolic acid? A. vancomycin B. penicillin C. methicillin D. isoniazid E. bacitracin

D. isoniazid

Which of the following drugs does NOT target peptidoglycan? A) Penicillin B) Cephalosporin C) Vancomycin D) Bacitracin E) Doxycycline

E) Doxycycline

Which test is used to determine the susceptibility of a microorganism to an antimicrobial? A) Minimum inhibitory concentration B) Minimum bactericidal concentration C) Minimally-lethal dose D) Antibiotic stimulating zone test E) Kirby-Bauer test

E) Kirby-Bauer test

An elderly patient comes to see you complaining of a very painful rash. When he lifts his shirt, you see that he has a rash of small blisters (vesicles) on one side of his back. You think he likely has shingles, caused by varicella-zoster virus (VZV), a double-stranded DNA virus that belongs to the Herpesviridae family. You explain this to your patient, who asks you to please give him an antibiotic for his infection. You tell him an antibiotic will not help him, and give him information on virus infections and their treatment. Acyclovir interferes with viral DNA replication. Other mechanisms of antiviral medications include all of the following EXCEPT: A) preventing fusion and inhibiting viral entry into a host cell. B) interfering with viral uncoating and release of viral nucleic acid in a host cell. C) preventing the assembly viral proteins to form capsids. D) inhibition of viral particle release from host cells. E) destroying viral ribosomes and preventing protein synthesis.

E) destroying viral ribosomes and preventing protein synthesis. No viral ribosomes. Uses the host cell's, remember?

T/F - Viruses are very effectively treated with antibiotics.

False

False Antibiotics don't work on viruses, antivirals do.

T/F - Carbapenems are easily inactivated by the extended-spectrum β-lactamases (ESBLs) produced by certain Gram-negative bacteria so cannot be usedto treat these infections.

False Beta-lactam antibiotic, carbapenems are NOT easily inactivated by ESBLs produced by certain G- bacteria so they are usually reserved as a last resort for treating severe diseases caused by ESBL-producing organisms. p.507

The most effective form of penicillin is: A. B. E. G.

Please select the statement regarding antimicrobial testing that is FALSE. The MIC and the MBC are quantitative measures of a bacterial strain's susceptibility to an antimicrobial medication. In the Kirby-Bauer disc diffusion test, a clear zone around the antibiotic disc following incubation indicates that the antibiotic is bactericidal. Disc diffusion tests can determine whether an organism is susceptible, intermediate, or resistant to a variety of different antimicrobials. In the Kirby-Bauer test, the clear area in which there is no visible growth of bacteria is called a zone of inhibition. Commercial tests for determining antimicrobial sensitivity are less labor-intensive and often more rapid than conventional tests.

In the Kirby-Bauer disc diffusion test, a clear zone around the antibiotic disc following incubation indicates that the antibiotic is bactericidal. might just be bacteristatic.

Which of the following drugs is incorrectly paired with its mode of action? Reverse transcriptase inhibitor: binds to DNA polymerase Actinomycin: blocks DNA replication Quinolones: inhibit DNA gyrase AZT: nucleotide analogs are incorporated into

Reverse transcriptase inhibitor: binds to DNA polymerase

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

Spectrum of activity

A drug that inhibits the growth of protozoan cells would not be expected to affect which of the following cell structures? The cell wall The cytoplasmic membrane Mitochondria Ribosomes

The cell wall Protozoan are single celled eukaryotes that don't have cell walls.

T/F - Antifungal drugs usually target the cell membrane.

True

T/F - Antimicrobial resistance can be due to spontaneous mutation or gene acquisition.

True

Folic acid is ultimately used in the synthesis of topoisomerases. proteins. DNA gyrases. sulfonamides. coenzymes.

coenzymes.

Sulfonamides are similar in structure to: DNA gyrases. LPS. ribosomes. PABA.

PABA. Sulfonamides are structural analogs of para-aminobenzoic acid (PABA) and thus act as competitive antagonists in microbial cells. Microbes need PABA to form dihydrofolic acid, a precursor of folic acid. Folic acid is required for purine and pyrimidine synthesis and hence nucleic acid synthesis. Sulfonamides not only block formation of folic acid - they are incorporated into the precursors, forming a pseudometabolite that is reactive and antibacterial. Mammalian cells are not susceptible to sulfonamides as they absorb and use preformed folic acid, resulting in a wide therapeutic index.

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

False

Penicillin was discovered by: Koch. Hooke. Fleming. Ehrlich.

Fleming. He saw, in a dish of Staphylococcus aureus, that growth near a contaminating Penicillium mold was inhibited. The substance he called penicillin but he couldn't purify it and so gave up. 10 years later, Chain and Florey purified it, helped a sick policeman (who died when it ran out), purified more and later cured 2 people. Penicillin G - first antibiotic (naturally produced antimicrobial).

The most common method of transfer of antimicrobial resistance is through the use of: viruses. R plasmids. introns. exons.

R plasmids. Conjugation - plasmid transfer - other microorganisms become resistant too.

An antibiotic made by microorganisms and modified by chemists is called: A) anti-metabolic. B) catabolic. C) semi-synthetic. D) synthetic. E) semi-catabolic.

C) semi-synthetic.

All of the following interfere with the function of the ribosomes except: a) fluoroquinolones b) lincosamides c) macrolides d) streptogramins e) tetracyclines

a) fluoroquinolones

Which of the following is the target for beta-lactam antibiotics? a) peptidoglycan synthesis b) DNA synthesis c) RNA synthesis d) Protein synthesis e) Folic acid synthesis

a) peptidoglycan synthesis

Which of the following statements is false concerning antiviral drugs? a. macrolide drugs block attachment sites on the host cell wall and prevent viruses from entering b. drugs that neutraize the acidity of phagolysosomes prevent viral uncoating c. nucleotide analogs in antiviral drugs can be used to stop viral replication d. drugs containing protease inhibitors retard viral growth by blocking the production of essential viral proteins

a. macrolide drugs block attachment sites on the host cell wall and prevent viruses from entering

Which of the following is most closely associated with a beta-lactam ring? a. penicillin b. vancomycin c. bacitracin d. isoniazid

a. penicillin

The key to successful chemotherapy is: a. selective toxicity b. a diffusion test c. the minimum inhibitory concentration test d. the spectrum of action

a. selective toxicity Harm to the targeted cells, minimal harm to the healthy cells/tissue.

In a Kirby-Bauer susceptibility test, the presence of a zone of inhibition around disks containing anitmicrobial agents indicates: a. that the microbe does not grow in the presence of the agents b. that the microbe grows well in the presence of the agents c. the smallest amount of the agent that will inhabit the growth of the microbe d. the minimum amount of an agent that kills the microbe in question

a. that the microbe does not grow in the presence of the agents

What was the first practical antimicrobial agent to be widely used? - Penicillin - Vancomycin - Sulfanilamide - Arsenic compounds

- Sulfanilamide Scientist responsible for the discovery of sulfanilamide, the first practical antimicrobial agent used to treat a wide array of bacterial infections. Gerhard Domagk.

Why are viruses more susceptible to nucleotide analogs than their host cells? - Viral DNA polymerases break down nucleotide analogs into toxic by-products, leading to the inactivation of the virus. - The coverings of most viruses are more permeable to nucleotide analogs than are the cytoplasmic membranes of host cells. - Viral DNA is distorted by the presence of nucleotide analogs, whereas the host DNA is not. - Viruses replicate their nucleic acid more rapidly than host cells do.

- Viruses replicate their nucleic acid more rapidly than host cells do.

Antimicrobials that kill microorganisms have the suffix: -cidal. -static. -anti. -genic.

-cidal Bacteriostatic = inhibits bacterial growth

Antimicrobials that inhibit the growth of microorganisms have the suffix: -cidal. -static. -anti. -genic.

-static

A commercial modification of the disk diffusion test is called the: A) E test. B) D test. C) C test. D) B test. E) A test.

A) E test.

What is the minimum inhibitory concentration (MIC)? A) It is the lowest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vitro. B) It is the highest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vitro. C) It is the lowest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vivo. D) It is the highest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vivo. E) It is the lowest concentration of a specific antimicrobial medication that kills 99.9% of cells of a given bacterial strain in vitro.

A) It is the lowest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vitro. -in vitro - in the lab, in vivo - in life

Compliance problems are leading to a large increase in antibiotic resistant strains of: A) Mycobacterium. B) Streptococcus. C) Staphylococcus. D) Pseudomonas. E) Mycoplasma.

A) Mycobacterium. slide 63

What allows for selective toxicity in a medication? A) The medication acts against an essential component or biochemical process of microorganisms that does not exist in human cells. B) The medication is converted into a non-toxic form by the liver in people, but remains highly toxic in bacteria which cannot process the drug. C) The medication acts against an essential component or biochemical process of human cells that does not exist in microorganisms. D) Only some medications cross from the blood into the cerebrospinal fluid of humans. E) Some medications have a very extended half-life AND only some medications cross from the blood into the cerebrospinal fluid of humans.

A) The medication acts against an essential component or biochemical process of microorganisms that does not exist in human cells.

Why must vancomycin be administered intravenously except when used to treat intestinal infections? A) Vancomycin is poorly absorbed from the intestinal tract. B) Vancomycin is toxic but less so if injected intravenously. C) Injected vancomycin is easier to target to the site of infection. D) Vancomycin is effective against only Gram-positive bacteria. E) Vancomycin has a high therapeutic index.

A) Vancomycin is poorly absorbed from the intestinal tract. p.507. Vancomycin is a glycopeptide antibiotic - most widely used one in the US. "Vancomycin in poorly absorbed from the intestinal tract, so it must be administered intravenously except when used to treat intestinal infections."

Sulfonamides work as: A) competitive inhibitors. B) noncompetitive inhibitors. C) ribosome-binding molecules. D) feedback inhibitors. E) coenzymes.

A) competitive inhibitors.

Which of the following microbes is of growing concern due to increasing resistance to "first-line medications," including isoniazid and rifampin.: A. Mycobacterium tuberculosis B. Enterobacteriaceae C. Staphylococcus aureus D. Streptococcus pneumoniae

A. Mycobacterium tuberculosis

What would be the effect of using a medication combination where one medication is bacteriostatic and the other is bactericidal for actively dividing cells only? A. The medications would interfere with each other and become less effective. B. The medications would enhance each others activity by killing microbes that are both slow growing and fast growing. C. The medications would have no effect on each other since they target two different things.

A. The medications would interfere with each other and become less effective.

What are two advantages of automated tests used to determine antimicrobial susceptibility? A) They are easier to perform. B) They produce results more quickly than conventional tests. C) They produce results more quickly than conventional tests AND they are easier to perform. D) They take longer to perform BUT they give fewer false results. E) They are cheaper than conventional tests AND they give more accurate results.

C) They produce results more quickly than conventional tests AND they are easier to perform.

In which of the following categories of antimicrobial drugs are the fewest drugs available? Antibacterial Antifungal Antiviral Antiprotozoan

Antiviral

One of the earliest researchers to explore the use of chemicals to kill microbial pathogens was: A) Koch. B) Ehrlich. C) Hooke. D) Fleming. E) Salvarsan.

B) Ehrlich He saw that bacterial cells took up dye differently than animal cells and realized that there must be some fundamental difference between them - thought it might be possible to find a chemical that selectively harms bacteria w/o affecting human cells (some "Magical Bullet"). The 606th arsenic compound he tested, arsphenamine, treated syphilis in animals. medication given name Salvarsan = salvation + arsenic. His discovery proved that some chemclals could selectively kill microbes.

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. 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 make them resistant to the drugs. B) It is highly unlikely that the microbe might spontaneously develop two specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the second drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall. C) All drugs work antagonistically with each other. 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 make them resistant to the drugs. D) Drugs can also select for mutations that will enhance the activity of another drug. Therefore, each of the paired drugs will help to select for spontaneous mutations that enhance the activity of the other drug in the pair. E) Bacteria can only ever develop resistance to a single antibiotic. If more than one drug is used, the organisms will definitely become resistant to one of them but it will not become resistant to both of them. The second antibiotic will kill the organism.

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

The lowest concentration of a drug that prevents growth of a microorganism is the: A) infectious effective dose. B) minimum inhibitory concentration. C) lethal dose. D) most effective concentration. E) minimal death dose.

B) minimum inhibitory concentration. MIC. Find via serial dilutions, use to create pate counts to find the minimum bactericidal concentration (MBC).

Prontosil effectively acted on streptococci when the drug was split by enzymes to produce: A) penicillin. B) sulfanilamide. C) erythromycin. D) Salvarsan. E) Salvarsan AND penicillin.

B) sulfanilamide. Penicillin was an incidental observation of mold, not synthesized in a lab. Domagk discovered that a red dye called Prontosil could be used to treat streptococcal infections in animals. The Prontosil had no effect ion streptococci in test tubes. Why? Enzymes in blood split the Prontosil molecules producing a smaller molecule = sulfanilamide, which acts against the infecting streptococci. The discery of sulfanilamide -> first of the class of sulfa drugs was luck + science.

Antiviral drugs may target all of the following EXCEPT: A) viral uncoating. B) viral ribosomes. C) nucleic acid synthesis. D) viral assembly. E) viral entry.

B) viral ribosomes.

Which of the following is NOT a target of drugs that inhibit protein synthesis? A. the shape of the 30S ribosomal subunit B. interference with alanine-alanine bridges C. the enzymatic site of the 50S ribosomal subunit D. movement of the ribosome from one codon to the next E. the tRNA docking site

B. interference with alanine-alanine bridges

The use of Salvarsan and Prontosil to treat microbial infections were early examples of: A) antibiotics. B) toxins. C) chemotherapy. D) inhibitors. E) vaccination.

C) chemotherapy p.501 Salvarsan and Prontosil are chemotherapeuitc agents, meaning chemicals used to treat disease. Because they are used to treat microbial infections, they can also be called antimicrobial medications, antimicrobial drugs, or, more simply, antimicrobials.

Inhibitors of protein synthesis typically act on: A) peptidoglycan precursors. B) penicillin-binding proteins. C) ribosomes. D) porin proteins. E) transfer RNA.

C) ribosomes. The 30S and 50S of the bacterial 70S ribosome.

Which of the following would you prescribe to treat a person with M. pneumoniae? A) A β-lactam antibiotic such as penicillin B) A glycopeptide antibiotic such as vancomycin C) Bacitracin D) A macrolide such as erythromycin E) Bacitracin OR penicillin

D) A macrolide such as erythromycin Macrolides work by binding to a specific subunit of ribosomes (sites of protein synthesis) in susceptible bacteria, thereby inhibiting the formation of bacterial proteins. In most organisms this action inhibits cell growth; however, in high concentrations it can cause cell death. - includes erythromycin, roxithromycin, azithromycin and clarithromycin.

Mycolic acids are targeted by isoniazid in the treatment of: A) S. aureus. B) S. epidermidis. C) M. luteus. D) M. tuberculosis. E) E. coli.

D) M. tuberculosis. isoniazid is a first line drug against TB.

Which is true of aminoglycosides? A) They are bacteriostatic AND they reversibly bind to the 30S ribosomal subunit. B) They irreversibly bind to the 30S ribosomal subunit AND they block DNA replication. C) They block peptidoglycan synthesis AND they bind to the 80S ribosomal subunit. D) They are bactericidal AND they block DNA replication. E) They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal.

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

penicillin binding proteins (PBPs): 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.

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

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. Thus, these drugs can only work when the virus is actively replicating as well. E) Nucleoside analogs work by being incorporated into growing strands of amino acids during enzyme synthesis. This indirectly shuts down further extension of these chains. However, new viral proteins are only being created when the virus is replicating, so these medications only work if that is the case.

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. Thus, these drugs can only work when the virus is actively replicating as well.

The first example of an antimicrobial drug synthesized in the laboratory was: A) penicillin. B) sulfa. C) erythromycin. D) Salvarsan. E) Erlichsan.

D) Salvarsan - an arsenic compound, Ehrlich tried and on the 606th try, got it right.

The arsenic compound that proved highly effective in treating syphilis was called: A) penicillin. B) sulfa. C) erythromycin. D) Salvarsan. E) erlichsan.

D) Salvarsan arsphenamine (Salvarsan) - Ehrlich - syphilis

Which statement about penicillins is INCORRECT? A) Penicillins + β-lactamase inhibitor is a combination of agents that protects the penicillin against enzymatic digestion. B) Broad-spectrum penicillins are active against penicillin-sensitive Gram-positive bacteria and also many Gram-negative bacteria. C) Some S. aureus strains have the ability to make altered penicillin binding proteins to which most β-lactam antibiotics do not bind as well. D) The penicillins produced naturally by the mold P. chrysogenum are broad-spectrum, effective against all Gram-positive and many Gram-negative bacteria. E) Bacteria that produce penicillinase are resistant to the natural penicillins.

D) The penicillins produced naturally by the mold P. chrysogenum are broad-spectrum, effective against all Gram-positive and many Gram-negative bacteria. - these penicillins are NARROW SPECTRUM

Spontaneous development of resistance to a particular antimicrobial is difficult if the drug: A) targets a single type of molecule AND binds to a single site on that target molecule. B) targets several different molecules AND affects the cytoplasmic membrane. C) affects only one molecule. D) affects the cytoplasmic membrane. E) binds to several sites on the target molecule AND targets several different molecules.

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

The zone size obtained in the Kirby-Bauer test is influenced by the drug's: A) molecular weight AND concentration. B) stability. C) concentration AND stability. D) molecular weight AND stability. E) molecular weight, stability, AND concentration.

E) molecular weight, stability, AND concentration.

Antimicrobials may cause all of the following EXCEPT: A) allergic reactions. B) toxic effects. C) suppression of normal microbiota. D) dysbiosis. E) resistance in people.

E) resistance in people. Bacteria can become resistant to antimicrobials, the meds aren't against the host!

Which of the following statements is true of selective toxicity? A. Selective toxicity takes advantage of structural differences between host and pathogen. B. To be effective, an antimicrobial agent must be more toxic to the patient than the pathogen. C. Selective toxicity takes advantage of metabolic differences between host and pathogen. D. Antimicrobial agents must target structural differences between host and pathogen and be more toxic to the patient than the pathogen. E. Selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen.

E. Selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen.

Which of the following bacteria have an innate resistance to penicillin? S. aureus S. epidermidis M. luteus Mycoplasma

Mycoplasma With no cell wall and not peptidoglycan synthesis - what's a penicillin to do?

T/F - Antimicrobials that have a high therapeutic index are less toxic to the patient.

True

T/F - Beta-lactam drugs are only effective against growing bacteria.

True

T/F - Certain antimicrobials may be life-threatening.

True

T/F - Drugs that target peptidoglycan do not affect eukaryotes.

True

Which statement about antiviral medications is INCORRECT? Nucleoside analogs and nucleotide analogs that interfere with the activity of reverse transcriptase are used in HIV treatment, along with at least one antiviral other medication. Viral replication generally uses host cell machinery; because of this, there are many targets for selectively toxic antiviral medications. Neuraminidase inhibitors inhibit neuraminidase, an enzyme encoded by influenza viruses that is important for the release of viral particles from infected host respiratory epithelial cells. Sofosbuvir is a nucleotide analog that interferes with HCV's replicase and is extremely effective when used in combination with at least one other anti-HCV medication. Available antivirals are virus-specific and target viral entry, viral uncoating, nucleic acid synthesis, integrase, and the assembly and release of viral particles.

Viral replication generally uses host cell machinery; because of this, there are many targets for selectively toxic antiviral medications.

Which of the following statements is false? a) a bacteriostatic chemical stops the growth of a microorganism b) The lower the therapeutic index, the less toxic the medication c) Broad-spectrum antibiotics are associated with the development of severe Clostridium difficile infections d) Azithromycin has a longer half-life than does penicillin V e) Chloramphenicol can cause a life-threatening type of anemia

b) The lower the therapeutic index, the less toxic the medication High therapeutic index is less to toxic to patient, low therapeutic index means the therapy dose is close to the toxic dose and the pt must be monitored carefully.

The target of the sulfonamides is: a) cytoplasmic membrane proteins b) folate synthesis c) gyrase d) peptidoglycan biosynthesis e) RNA polymerase

b) folate synthesis

The rate of elimination of an antimicrobial is expressed as its: a. metabolic destructive rate. b. half-life. c. effective time. d. dosage rate.

b. half-life. The time it takes for the concentration in the blood to decrease by half (50%).

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 pathoge

b. less toxic to the patient. Selective toxicity = means harmful to one, not to the other.

All members of the penicillin family have: beta-lactam rings. alpha-lactam rings. phenolic rings. sulfanilic rings.

beta-lactam rings. beta-lactamases break the beta-lactam rings and inactivate these antimicrobial drugs.

Antibiotics that are most likely to disrupt the normal flora are termed: narrow-spectrum. broad-spectrum. targeted spectrum. semi-synthetic

broad-spectrum. Narrow spectrum affect a limited range and are less disruptive to normal microbiota.

The anti fungal medication griseofulvin is used to treat: a) vaginal infections b) systemic infections c) nail infections d) eye infections

c) nail infections

Penicillin has been modified to make derivatives that differ in all of the following except: a) spectrum of activity b) resistance to beta-lactamases c) potential for allergic reactions d) a and c

c) potential for allergic reactions

Which of the following statements is relevant in explaining why sulfonamides are effective? a. sulfonamides attach to sterol lipids in the pathogen, disrupt the membranes, and lyse the cells b. sufonamides prevent the incorporation of amino acids into the polypeptide chains c. humans and microbes use folic acid and PABA differently in their metabolism d. sulfonamides inhibit DNA replication in both pathogens and human cells

c. humans and microbes use folic acid and PABA differently in their metabolism

Routine antimicrobial therapy to treat tuberculosis involves taking: a) one medication for 10 days b) two or more medications for 10 days c) one medication for at least 6 months d) two or more medications for at least 6 months e) five medications for 2 years

d) two or more medications for at least 6 months

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.

d. All of the choices are correct.

Fluoroquinolones typically target: a. ribosomes. b. penicillin-binding proteins. c. peptidoglycan. d. DNA gyrase.

d. DNA gyrase. Fluoroquinolones mess with nucleic acid synthesis.

Drugs that act against protein synthesis include: a. beta-lactams b. trimethoprim c. polymyxin d. aminoglycosides

d. aminoglycosides

Diffusion and dilution tests that expose pathogens to antimicrobials are designed to: a. determine the spectrum of action of a drug b. determine which drug is most effective against a particular pathogen c. determine the amount of a drug to use against a particular pathogen d. both b and c

d. both b and c

Drugs that are bacteriostatic: a. kill bacteria. b. promote bacterial growth. c. inactivate bacterial spores. d. inhibit the growth of bacteria.

d. inhibit the growth of bacteria. Bacteriocidal = kills bacteria

Cross resistance is: a. the deactivation of an antimicrobial agent by a bacterial enzyme b. alteration of the resistant cells so that an antimicrobial agent cannot attach c. the mutation of genes that affect the cell membrane channels so that antimicrobial agents cannot cross into the cell's interior d. resistance to one antimicrobial agent because of its similarity to another antimicrobial agent

d. resistance to one antimicrobial agent because of its similarity to another antimicrobial agent

PABA is: a. a substrate used in the production of penicillin b. a type of B-lactamase c. molecularly similar to cephalosporins d. used to synthesize folic acid

d. used to synthesize folic acid

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

e. aminoglycosides, tetracyclines AND macrolides Bacitracins mess with cell wall synthesis.

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.

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

Antiviral drugs may target: a. uncoating. b. nucleic acid synthesis. c. viral assembly. d. viral ribosomes. e. uncoating, nucleic acid synthesis AND viral assembly

e. uncoating, nucleic acid synthesis AND viral assembly

Drugs that are more effective when taken together are called: energetic. antagonistic. subtractive. synergistic.

Microbiology, Ch 20, Nester's 9th

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