CH. 9 : Antimicrobial chemotherapy
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