Chapter 9 Antimicrobial Chemotherapy

Antiviral agents are _____ referred to as "antibiotics."

NEVER

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 tetracycline family of antibiotics interfere with ___________synthesis in bacteria

protein

The antibiotic Gentamicin C1a, 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

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

Which of the following statements about carbapenems and monobactams is false? a) These drugs cannot be taken orally. b) Recently, β-lactamases that inactivate these drugs have been discovered. c) These drugs have β-lactam rings. d) These drugs are heavily used clinically.

d) These drugs are heavily used clinically.

Which of the following is a synthetic antibiotic that interferes with the production of folic acid? a) Cephalosporin b) Methicillin c) Tetracycline d) Trimethoprim

d) Trimethoprim Trimethoprim is a synthetic antibiotic that inhibits production of folic acid by binding to dihydrofolate reductase. Trimethoprim has a wide spectrum of activity and is bacteriostatic

Which of the following characteristics does not apply to tetracycline? a) Inhibits protein synthesis b) Is a broad spectrum antibiotic c) Has a four ring structure d)Is bactericidal

d) is bactericidal

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

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

low therapeutic

sulfa drugs block __________synthesis

folic acid

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

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

less than

aminoglycosides bind to the ____________

30S ribosomal subunit

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

50S ribosomal subunit

Macrolide antibiotics interfere with protein synthesis by binding to the ______________

50S ribsomal subunit

oxazolidinones prevent formation of the ___________

70S initiation complex

Drug-tolerant bacteria do not respond to antibiotics because they ________________ or they _______________

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

Which five of the following are classes of drugs used to manage HIV infection? a) Nucleoside reverse transcriptase inhibitors b) Integrase inhibitors c) Protease inhibitors d) Dihydrofolate reductase inhibitors e) DNA polymerase inhibitors f) Nonnucleoside reverse transcriptase inhibitors g) Fusion inhibitors h) Neuraminidase inhibitors

1. a) Nucleoside reverse transcriptase inhibitors 2. b) Integrase inhibitors 3. c) Protease inhibitors 4. f) Nonnucleoside reverse transcriptase inhibitors 5. g) Fusion inhibitors

Acyclovir blocks the activity of viral _______ ______enzyme.

Acceptable Answers: DNA polymerase or herpes simplex

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

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

C. difficile

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

DNA gyrase and topoisomerase

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.

Eukarya

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

False; Chloramphenicol is quite toxic and can cause allergic problems and dysfunction in the bone marrow.

True or false: Most antifungal agents are fungicidal.

False; Most antifungal drugs are fungistatic if they can be maintained at adequate levels.

True or False: The macrolide antibiotics are bactericidal

False; The Macrolides are usually bacteriostatic

Why are there fewer antifungal drugs than antibacterial drugs?

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

The acronym "MRSA" stands for ______-_____________ _____________ ___________

Methicillin- resistant Staphylococcus aureus

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

Systemic

___________ mycoses are the most difficult to control

Systemic or deep

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

True; Nucleic acid synthesis is a process that both humans and microbes engage in.

True or false: The tetracyclines are bacteriostatic.

True; Tetracyclines only inhibit growth of target bacteria

True or false: Trimethoprim is a synthetic antibiotic.

True; Trimethoprim is a synthetic antibiotic that interferes with the production of folic acid.

The acronym "VRE" stands for ____________-__________ __________

Vancomycin-resistant enterococci.

Which two of the following are NOT targets of antibacterial drugs that inhibit nucleic acid synthesis? a) 80S Ribosome b) DNA Polymerase c) Topoisomerase d) Dihydrofolate reductase

a) 80S Ribosome d) Dihydrofolate reductase

Which two of the following characteristics apply to tamiflu? a) Blocks release of new viruses from host b) Inhibits reverse transcriptase c) Inhibits hemagglutinin d) Inhibits neuraminidase

a) Blocks release of new viruses from host d)Inhibits neuraminidase

Which two of the following are targets of antibacterial drugs that inhibit nucleic acid synthesis? a) DNA Polymerase b) Topoisomerase c) 80S Ribosome d) Dihydrofolate reductase

a) DNA Polymerase b) Topoisomerase

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

acceptable answers: peptidoglycan, nam-nag, or nag-nam

The type of antibiotic resistance that is due to a change in the genome of a bacterium that converts it from a sensitive cell to a resistant cell is called ________resistance.

acquired

Based on its chemical structure, the antibiotic Gentamicin C1a, 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

Which two of the following characteristics apply to aminoglycosides? a) Inhibit cell wall synthesis b) Bind to 30S ribosomal subunit c) Synthesis of abnormal proteins d) Often a drug of last resort e) Inhibit gyrase activity

b) Bind to 30S ribsomal subunit c) Synthesis of abnormal proteins

Which of the following characteristics applies to antifungal drugs? a) Have a high therapeutic index b) Have a low therapeutic index c) Have a medium range therapeutic index

b) Have a low therapeutic index Since fungi are eukaryotes, many of the drugs that inhibit or kill fungi are quite toxic to people and therefore, these drugs are collectively considered to have a low therapeutic index.

Antiprotozoan drugs are NOT known to target which of the following? a) Membrane synthesis b) Metabolic processes c) Nucleic acid synthesis

b) Membrane synthesis

Which of the following are targets of antifungal agents? a) Cell wall synthesis b) Membrane synthesis c) Folic acid synthesis d) Peptidoglycan synthesis

b) Membrane synthesis

Which two of the following are targets of antiprotozoan agents? a) Cell wall structure b) Nucleic acids c) Membrane sterol synthesis d) Metabolic processes

b) Nucleic acids d) Metabolic processes

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

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

broad-spectrum

Which two of the following statements about antimetabolites are true? a) Antimetabolites form a precipitation complex with a natural substrate of enzyme. b) Antimetabolites bind to 30S ribosomal subunit and block formation of the initiation complex. c) Antimetabolites compete with a natural substrate for binding at the active site. d) Antimetabolites have a similar structure to the substrate of the target enzyme.

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

Which of the following is a broad spectrum antibiotic? a) Penicillin V b) Ciprofloxacin c) Chloramphenicol d) Methicillin

c) Chloramphenicol

Which of the following is NOT a side effect of aminoglycoside antibiotic use? a) Allergic reaction b) Kidney damage c) Liver damage d) Loss of balance

c) Liver damage

Which of the following is NOT a class of drug used to manage HIV infections? a) NNRTI b) Fusion inhibitor c) Topoisomerase inhibitor d) NRTI

c) Topoisomerase inhibitor

Which two of the following characteristics do not apply to macrolide antibiotics? a) Is a broad spectrum antibiotic b) Is usually bacteriostatic c) Has a four ring structure d) Inhibits DNA replication

c) has a four ring structure d) inhibits DNA replication

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

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

chloramphenicol Macrolides

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

sulfonamides have a high therapeutic index because __________

humans do not have the pathways inhibited by the drug

A consequence of the fact that humans do not synthesize folate (humans must obtain it in our diet) but bacteria do is that _____.

inhibitors of the folate pathway have a high therapeutic index

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

The macrolide antibiotics are characterized by a _____.

lactone ring with one or more sugars attached

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

less selectively toxic

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

narrow-spectrum

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

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 first drug to successfully treat tuberculosis was _____.

streptomycin

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

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.

synergistic

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

The therapeutic index is the ratio of the _____.

toxic dose to therapeutic dose