Microbiology, Ch 20, Nester's 9th

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?

Sulfonamides are similar in structure to:

PABA. Sulfonamides are structural analogs of para-aminobenzoic acid (PABA) and thus act as competitive antagonists in microbial cells.

Trimethoprim and sulfonamides have a(n):

synergistic effect.

Drugs that are more effective when taken together are called:

synergistic.

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.

Routine antimicrobial therapy to treat tuberculosis involves taking:

d) two or more medications for at least 6 months

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 drugs target peptidoglycan? a. penicillin b. cephalosporinm c. vancomycin d. bacitracin 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.

Which is the correct definition of selective toxicity?

- A medication causing greater harm to a pathogen than to the host.

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

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.

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

False

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

False

A drug that inhibits the growth of protozoan cells would not be expected to affect which of the following cell structures?

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

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

True

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

True

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

99.9%

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

True

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

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.

Why are viruses more susceptible to nucleotide analogs than their host cells?

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

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

Antimicrobials that kill microorganisms have the suffix:

-cidal

A commercial modification of the disk diffusion test is called the:

A) E test.

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.

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. -in vitro - in the lab, in vivo - in life

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

A) Mycobacterium.

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. Which of the following targets would you expect to be the most selective with respect to toxicity?

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

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.

Why must vancomycin be administered intravenously except when used to treat intestinal infections?

A) Vancomycin is poorly absorbed from the intestinal tract.

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.

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.

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.

Sulfonamides work as:

A) competitive inhibitors.

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).

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.

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

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

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

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.

In which of the following categories of antimicrobial drugs are the fewest drugs available?

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

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

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.

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:

B) antagonistic.

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

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

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.

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 ________.

B) peptidoglycan synthesis; protein synthesis

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.

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. A nucleoside analog can be phosphorylated in vivo by a virally encoded or normal cellular enzyme to form a nucleotide analog—a chemical structurally similar to the building blocks of DNA and RNA. Nucleotide analogs interfere with:

B) viral nucleic acid synthesis.

Antiviral drugs may target all of the following EXCEPT:

B) viral ribosomes.

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

B. Streptococcus pneumoniae

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

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

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.

What are two advantages of automated tests used to determine antimicrobial susceptibility?

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

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:

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:

C) broad-spectrum.

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. Several diseases caused by herpesviruses are treated with a medication called acyclovir. This medication is a nucleoside analog, meaning:

C) it contains a nucleotide analog and a sugar.

Inhibitors of protein synthesis typically act on:

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

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.

Explain the difference between MIC and MBC.

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?

C. their activity against cell walls

Which of the following would you prescribe to treat a person with M. pneumoniae?

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:

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

Please select the TRUE statement regarding bacterial resistance to antimicrobials.

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.

Why are nucleoside analogs active only against replicating viruses?

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.

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

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.

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

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:

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:

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):

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

D. both susceptibility and MIC

Which of the following drugs specifically targets cell walls that contain arabinogalactan-mycolic acid?

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?

E) Kirby-Bauer test

Which is true of aminoglycosides?

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

penicillin binding proteins (PBPs):

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

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

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

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

G

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?

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

E) molecular weight, stability, AND concentration.

Antimicrobials may cause all of the following EXCEPT:

E) resistance in people.

Which of the following statements is true of selective toxicity?

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

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. T/F - Antibiotics are effective in treating viral infections provided that they are given early in the course of illness.

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

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

Fleming. Penicillin G - first antibiotic (naturally produced antimicrobial).

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.

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

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

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

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

True

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

True

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

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.

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

a) fluoroquinolones

Acyclovir is a:

a) nucleoside analog

Which of the following is the target for beta-lactam antibiotics?

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

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

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

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

antibiotics.

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:

b) folate synthesis

The rate of elimination of an antimicrobial is expressed as its:

b. half-life.

A high therapeutic index is:

b. less toxic to the patient.

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

broad-spectrum.

The anti fungal medication griseofulvin is used to treat:

c) nail infections

Penicillin has been modified to make derivatives that differ in all of the following except:

c) potential for allergic reactions

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

Which of the following statements is relevant in explaining why sulfonamides are effective?

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

Folic acid is ultimately used in the synthesis of

coenzymes.

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

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:

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

Drugs that act against protein synthesis include:

d. aminoglycosides

Diffusion and dilution tests that expose pathogens to antimicrobials are designed to: 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:

d. inhibit the growth of bacteria.

Cross resistance is:

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

PABA is:

d. used to synthesize folic acid

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

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

Beta-lactamases:

e. break the beta-lactam ring.

Sulfonamide and trimethoprim are both:

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

The diffusion bioassay:

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

Antiviral drugs may target:

e. uncoating, nucleic acid synthesis AND viral assembly

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

streptomycin. (Ehrlich)

The toxicity of a given drug is expressed as the: selective toxicity.

therapeutic index TI = toxic dose/therapeutic dose - higher is better