CH. 9 : Antimicrobial chemotherapy

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Which five of the following are classes of drugs used to manage HIV infection?

Nonnucleoside reverse transcriptase inhibitors Protease inhibitors Fusion inhibitors Nucleoside reverse transcriptase inhibitors Integrase inhibitors

Which two of the following are targets of antiprotozoan agents?

Nucleic acids Metabolic processes

The era of modern antimicrobial chemotherapy began with the work of _______, who put forth the concept of a "magic bullet," a chemical that would selectively destroy pathogens without harming human cells.

Paul Ehrlich

Why are there fewer antiprotozoan drugs than antibacterial drugs?

Protozoa are eukaryotes and thus have fewer targets for drug action

Erythromycin and other macrolide antibiotics interfere with bacterial synthesis.

protein

The antibiotic chloramphenicol interferes with synthesis in bacteria.

protein

The antibiotic chloramphenicol interferes with synthesis in bacteria..

protein

The tetracycline family of antibiotics interfere with synthesis in bacteria.

protein

Aminoglycosides interfere with ____

protein synthesis

The antibiotic shown here inhibits bacterial growth by disrupting _____.

protein synthesis

The antiviral agent tamiflu blocks _____.

release of new virus particles from host

A consequence of HIV remaining dormant in memory T cells of the immune system is that HIV-positive individuals _____.

require drug therapy for life

Sulfa drugs and trimethoprim are often used together because lower dosages of each drug can be used. This type of interaction between drugs is called a(n) drug effect.

synergy

As a general rule, the (greater/smaller) therapeutic index, then the better the antimicrobial agent.

bigger

The side effects and toxicity of antiprotozoan drugs in humans is primarily due to _____.

the drugs targeting protozoan enzymes and processes also present in human cells

Penicillin disrupts cell wall formation by _____.

blocking the formation of peptidoglycan cross links

The tetracyclines are bacteriostatic.

true

Streptomycin is important historically because it was the first drug to successfully treat _____.

tuberculosis

The acronym "VRE" stands for -resistant enterococci.

vancomycin

The drug of last resort for the treatment of antibiotic resistant Staphylococcus aureus is

vancomycin

Methods to detect antimicrobial drug resistance include the use of the polymerase chain reaction (PCR). This method is appropriate because _____.

drug resistance determinants are genetically encoded

Bacteria that do not respond to antibiotics because they are embedded in a biofilm matrix or are growing too slowly to be inhibited are termed _____.

drug tolerant

A drug that disrupts a microbial structure or function not found in host cells has a _____ therapeutic index.

high

Sulfonamides have a high therapeutic index because _____.

humans do not have the pathways inhibited by the drug

Many antifungal agents disrupt _____ synthesis.

membrane

The acronym "MRSA" stands for -resistant Staphylococcus aureus.

methicillin

The concentration of drug necessary to prevent the growth of a pathogen is called the _____.

minimal inhibitory concentration

The first true antibiotic (a natural microbial product) to be used was

penicillin

Upon phosphorylation, the antiviral drug acyclovir inhibits viral _____.

DNA polymerase

The antimicrobial activity of the tetracycline family of antibiotics results from their binding to _______.

30S ribosomal subunit

Which of the following is not a target of fluoroquinolone drugs?

DNA polymerase

The therapeutic index of a protein synthesis inhibitor is _____ the therapeutic index of a cell wall inhibitor.

less than

Which of the following conditions has a significant contribution to the maintenance of drug resistant genes in a bacterial population?

Exposure of bacteria to the drug

Chloramphenicol has little to no side effects making it one of the best broad spectrum antibiotics.

False

Most antifungal agents are fungicidal.

False

Most antifungal agents are fungicidal..

False

There are more antiprotozoan agents than antibacterial agents.

False

Macrolide antibiotics interfere with protein synthesis by binding to _____.

50S ribosomal subunit

Many efflux pumps involved in bacterial resistance to antibiotics pump the drug from the cell as protons enter; this is what type of transporter?

antiport

Drug-tolerant bacteria do not respond to antibiotics because they

are embedded in a biofilm matrix that drugs can't penetrate grow too slowly to be inhibited by the drug

The antimicrobial activity of chloramphenicol results from its binding to _____.

50S ribosomal subunit

Which two of the following are NOT targets of antibacterial drugs that inhibit nucleic acid synthesis?

80S Ribosome Dihydrofolate reductase

The first drug to successfully treat tuberculosis was _____.

streptomycin

The therapeutic index is the ratio of the _____.

toxic dose to therapeutic dose

Select two examples of resistance to antibiotics due to inactivation of a drug.

Addition of acetyl-CoA to chloramphenicol The activity of beta-lactamase

Trimethoprim is a synthetic antibiotic.

True

Intrinsic resistance to antibiotics could be due to which one of these?

A particular structural feature of the bacterial cell

Which of the following are possible side effects of aminoglycoside antibiotic use?

Allergic reaction Loss of balance

A mutation that affects the ability of certain antibiotics to bind to the 23S rRNA subunit of ribosomes would be an example of which type of antibiotic resistance?

Acquired

Which of these mutations would be most likely to confer resistance to the antibiotic penicillin?

Acquisition of beta-lactamase activity

Which of these mutations would be most likely to confer resistance to the antibiotic vancomycin?

Alteration of the terminal D-alanine in the pentapeptide of peptidoglycan.

Which one of these mutations would be most likely to confer resistance to the antibiotic sulfonamide?

Altered activity of enzymes involved in folic acid synthesis

Which two of the following statements about antimetabolites are true?

Antimetabolites have a similar structure to the substrate of the target enzyme. Antimetabolites compete with a natural substrate for binding at the active site.

Which of the following statements concerning antivirals is false?

Antivirals are often referred to as antibiotics.

Many new antimicrobial agents have been discovered in which two soil inhabitants?

Bacteria Fungi

Which two of the following statements are true?

Fungal cells are more similar to human cells than to bacterial cells. Currently there are fewer antifungal agents than antibacterial agents.

An important limitation to the use of lincosamine antibiotics is that they can support the overgrowth of _____

C. difficile

An important limitation to the use of lincosamine antibiotics is that they can support the overgrowth of _____.

C. difficile

Which of the following is a broad spectrum antibiotic?

Chloramphenicol

Acyclovir blocks the activity of viral enzyme.

DNA simplex

Which two of the following are targets of antibacterial drugs that inhibit nucleic acid synthesis?

DNA Polymerase Topoisomerase

mycoses are the most difficult to control.

Deep

The concept of a "magic bullet," a chemical that would selectively destroy pathogens without harming human cells, was put forth by Paul , whose research sparked the era of modern antimicrobial chemotherapy.

Erlich

The side effects and toxicity of antiprotozoan drugs results from the fact that protozoans and humans are both members of Domain and have similar enzymes, processes, and pathways.

Eukaryota

Why are there fewer antifungal drugs than antibacterial drugs?

Fungal cells are more similar to human cells than bacterial cells.

Which of the following characteristics applies to antifungal drugs?

Have a low therapeutic index

Which statement is NOT consistent with current strategies for limiting the development of antibiotic resistance?

Increased usage of antibiotics in farm animal feed

Which two of the following characteristics do not apply to macrolide antibiotics?

Inhibits DNA replication Has a four ring structure

Which two of the following characteristics apply to tamiflu?

Inhibits neuraminidase Blocks release of new viruses from host

Which of the following characteristics does not apply to tetracycline?

Is bactericidal

The term bactericidal means that the antimicrobial agent bacteria, and bacteriostatic means that it reversibly the growth of the bacteria.

Kills and stops

Which of the following is NOT a side effect of aminoglycoside antibiotic use?

Liver damage

Antiprotozoan drugs are NOT known to target which of the following?

Membrane synthesis

Which of the following are targets of antifungal agents?

Membrane synthesis

Which two of the following characteristics apply to antifungal agents?

Most are fungistatic Many are toxic to human cells

Which three of these are strategies being used to minimize the spread of antibiotic resistance?

Searching for antimicrobial-producing organisms Computer modeling of potential drug targets Use of bacteriophage in clinical settings

Which three of the following are consistent with current strategies to prevent the emergence of drug resistance?

Strict control of broad-spectrum drug usage Combination drug therapy High dosages to kill susceptible and mutant microbes

Which two of the following characteristics apply to aminoglycosides?

Synthesis of abnormal proteins Bind to 30S ribosomal subunit

Which type of fungal infection is the most likely to be fatal?

Systemic

Select three examples of resistance to antibiotics that is due to an altered cellular target of the drug.

The terminal D-alanine of pentapeptide mutates to D-serine A change in the structure of 23S rRNA Alteration of an enzyme involved in folic acid synthesis

Which of the following statements about carbapenems and monobactams is false?

These drugs are heavily used clinically.

Which two of the following are examples of superficial mycoses?

Toenail fungus Oral candidiasis (thrush)

Which of the following is NOT a class of drug used to manage HIV infections?

Topoisomerase inhibitor

Which of the following is a synthetic antibiotic that interferes with the production of folic acid?

Trimethoprim

Antibacterial drugs that inhibit nucleic acid synthesis are not as selectively toxic as drugs that target other bacterial processes.

True

Select two examples of alternative metabolic pathways used by bacteria to resist the activity of an antibiotic.

Use preformed folic acid instead of synthesizing it Increase folic acid production

Which of the following is considered a "drug of last resort" when treating antibiotic resistant Staphylococcus aureus?

Vancomycin

Identify the mechanism of bacterial resistance to antibiotics (blue shapes) that is illustrated in the diagram inside the red circle.

alteration of target

Based on its chemical structure, the antibiotic shown here belongs to the class of drugs termed _____.

aminoglycosides

Lincosamine antibiotics have a broad spectrum of activity against _____.

anaerobes

A substance that blocks the functioning of a specific biochemical pathway is called a(n) _____.

antimetabolite

A(n) is an antimicrobial substance that antagonizes or blocks the function of a specific biochemical pathway.

antimetabolite

The screening of large numbers of soil and have led to the discovery of new antimicrobial agents.

bacteria and fungi

The therapeutic index of a protein synthesis inhibitor is less than the therapeutic index of a cell wall inhibitor because _____.

bacterial cells and host cells both use ribosomes for protein synthesis

Chloramphenicol is a spectrum antibiotic.

broad

The sulfonamides inhibit the growth of a wide variety of bacteria and are classified as -spectrum drugs.

broad

Drugs that are effective against a wide variety of pathogens are called _____ drugs.

broad-spectrum

The two newest classes of β-lactam drugs are

carbapenems monobactams

The highest therapeutic index is found with antimicrobial drugs that target synthesis.

cell wall

The most selective antibiotics in use target the bacterial .

cell wall wall

The most selective antibiotics target _____.

cell wall synthesis

Which of the following antibiotics inhibit protein synthesis by binding to the 50S ribosomal subunit?

chloramphenicol macrolides oxazolidinones

All aminoglycoside antibiotics contain a(n) ring and amino sugars.

cyclohexane

The aminoglycoside antibiotics are characterized by the presence of amino sugars and a _____

cyclohexane ring

The aminoglycoside antibiotics are characterized by the presence of amino sugars and a _____.

cyclohexane ring

The drugs that target the cell wall have a high therapeutic index because human cells _____.

do not have cell walls

One mechanism of antibiotic resistance involves the use of translocases, which are also called pumps.

efflux

Methods to test bacterial isolates for drug resistance include _____.

enzyme detection kits with a chromophore polymerase chain reaction

The lower the therapeutic index, the better the chemotherapeutic agent is.

false

The macrolide antibiotics are bactericidal.

false

Sulfonamides disrupt the synthesis of acid, a precursor of purines.

folate

Sulfa drugs block ________ synthesis.

folic acid

A consequence of the fact that humans do not synthesize folate but bacteria do is that _____

inhibitors of the folate pathway have a high therapeutic index

A consequence of the fact that humans do not synthesize folate but bacteria do is that _____.

inhibitors of the folate pathway have a high therapeutic index

The minimal concentration is the level of an antimicrobial agent required to stop the growth of a targeted pathogen.

inhibitory

The two major types of antibiotic resistance seen in bacteria are acquired resistance and resistance.

intrinsic

Penicillin is considered to be the first true antibiotic, meaning that it _____.

is a natural microbial product

Penicillin has a high therapeutic index because _____.

its cellular target, peptidoglycan, is absent from host cells

Most penicillin resistant bacteria produce enzymes called penicillinases that hydrolyze the β- ring of penicillin and render the molecule ineffective.

lactam

The most critical portion of the penicillin molecule is the β- , which is essential for the antimicrobial activity of the drug

lactam ring

The macrolides are a family of antibiotics that are characterized by a(n) ring that is linked to one or more sugars.

lactone

The macrolide antibiotics are characterized by a _____.

lactone ring with one or more sugars attached

In the absence of a drug, a population of drug-resistant bacteria should become _________ resistant to the drug.

less

Drugs that inhibit nucleic acid synthesis in bacteria are said to be ________.

less selectively toxic

Rifampin is the antibiotic used to treat infections by _____

mycobacteria

Rifampin is the antibiotic used to treat infections by _____.

mycobacteria

It is thought that penicillin blocks the bacterial enzymes that create crosslinks between polymers (strands) in the cell wall

nag-nam

It is thought that penicillin blocks the bacterial enzymes that create crosslinks between polymers (strands) in the cell wall.

nag-nam

Vancomycin is classified as a spectrum drug because it is only effective against Gram positive bacteria.

narrow

Drugs that are only effective against a limited variety of pathogens are called _____ drugs.

narrow-spectrum

Antiviral agents are _____ referred to as "antibiotics."

never

Chloramphenicol inhibits the 50S ribosome in bacterial and should be used ____________.

only in life-threatening situations due to human-toxicity

The antibiotic used to treat mycobacterial infections is _____.

rifampin

A successful antimicrobial agent has , the ability to kill or inhibit microbial pathogens with little or no damage to the host.

selective toxicity

The ability to kill or inhibit microbial pathogens while causing minimal damage to the host is called _____.

selective toxicity

Naturally occurring antibiotics that have been chemically modified are called ______.

semi-synthetic

The structure of sulfa drugs is characterized by a(n) ____

similarity to p-aminobenzoic acid

The structure of sulfa drugs is characterized by a(n) _____.

similarity to p-aminobenzoic acid

Antimetabolites are similar in structure to the of key enzymes and compete with them for binding at the enzyme active site.

substrates

The class of antibiotics that are structural analogues of p-aminobenzoic acid is the ____

sulfonamides

The class of antibiotics that are structural analogues of p-aminobenzoic acid is the _____.

sulfonamides

Toenail fungus and thrush are classified as mycoses.

superficial

When drugs interact in ways that enhance the effects of each other it is called a(n) ________ effect.

synergistic

HIV-infected individuals require drug therapy for life because _____.

the virus remains dormant in immune cells

Due to the similarities of human and fungal cells, most antifungal drugs have a low index.

therapeutic

The fluoroquinolones disrupt DNA replication and repair by targeting which two enzymes?

topoisomerase DNA gyrase

The therapeutic index is the ratio of the dose to the dose.

toxic therapeutic

The structural component of the penicillin molecule that is critical for antimicrobial activity is the _______.

β-lactam ring

The basis of penicillin resistance in bacteria is the ability to produce enzymes called penicillinases or _______.

β-lactamases


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