Ch.9
For consistency, the medium used for disk diffusion tests is _____ agar.
Mueller-Hinton
Which five of the following are classes of drugs used to manage HIV infection?
Nucleoside reverse transcriptase inhibitors Protease inhibitors Integrase inhibitors Nonnucleoside reverse transcriptase inhibitors Fusion inhibitors
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
The first true antibiotic (a natural microbial product) to be used was .
Penicillin
Match each antimicrobial agent with the person or persons who discovered it.
Penicillin--> Duchesne and fleming Sulfonamide--> Domagk Streptomycin--> Waksman Salavarsan--> Ehrlich and Hata
Which of the following is NOT a likely source antimicrobial agents?
Plant natural products
Which of the following causes a life threatening systemic mycosis in immunocompromised patients?
Pneumocystis jiroveci
Which of the following characteristics applies to fusion inhibitors?
Prevent entry of HIV into host cell
Which of the following characteristics applies to protease inhibitors?
Prevent processing of HIV polyprotein
Relapse of malaria results from activation of dormant Plasmodium in the liver. Which of the following drugs is effective in preventing relapse?
Primaquine
Why are there fewer antiprotozoan drugs than antibacterial drugs?
Protozoa are eukaryotes and thus have fewer targets for drug action
A combination of which two drugs are recommended for the treatment of malaria?
Quinine drug Artemisinin derivative
jiroveci causes a life threatening systemic mycosis in individuals who are immunocompromised.
pneumocystis
In the Kirby-Bauer assay pictured here, the antibiotic is _____.
present in the white disks
The mechanism of action of oxazolidinones is to inhibit protein synthesis by _____.
preventingthe assembly of the 70S initiation complex.
Relapse of malaria is prevented by the antiprotozoan drug___ which targets dormant Plasmodium in the liver.
primaquine
On this Petri dish showing the interaction of two microorganisms, the organism indicated by the letter B is _____.
producing compounds active against organism A
inhibitors prevent HIV maturation by blocking the processing of viral polyproteins.
protease
Erythromycin and other macrolide antibiotics interfere with bacterial synthesis.
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
In the assay shown here, the MIC is determined by _____.
reading where the zone of inhibition intersects the Etest strip
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
Vidarabine ointment contains adenine arabinoside, an antiviral agent that disrupts ______.
synthesis of viral DNA
The oxazolidinones are _____ antibiotics.
synthetic
Fluconazole, amphotericin, and 5-flucytosine are commonly used against ________ mycoses.
systemic
Which type of fungal infection is the most likely to be fatal?
systemic
mycoses are the most difficult to control.
systemic
alteration of target--> alternate pathways--> drug inactivation--> efflux pumps-->
terminal D-alanine in peptidoglycan changes to D-lactate use of preformed folic acid, rather than synthesis hydrolysis of beta-lactam ring by beta-lactamase antiport mechanism where protons enter cell as drug leaves
The are a family of antibiotics that are characterized by a four ring structure to which a variety of side chains are attached.
tetracyclines
Which three of the following are believed to be mechanisms of action of penicillin?
activate bacterial autolytic enzymes stimulate holins to form holes in the plasma membrane inhibit the transpeptidation reaction in peptidoglycan synthesis
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 two of the following are advantages of ketolides over macrolides?
better oral bioavailability better acid stability
Match each antibiotic with its mechanism of action. aminoglycosides--> macrolides--> oxazolidinones-->
bind to the 30S ribosomal subunit bind to the 50S ribosomal subunit prevent formation of the 70S initiation complex
Vancomycin has the same target as β-lactam antibiotics, the transpeptidation reaction in peptidoglycan synthesis, but it differs in that it _____.
binds to the enzyme's substrate
Fluoroquinolones are antibacterial drugs that _____.
block nucleic acid synthesis
Treatment of HIV infected patients with nonnucleoside inhibitors reverse transcriptase inhibitors (NNRTIs) results in ______.
blockage of HIV DNA synthesis
Penicillin disrupts cell wall formation by _____.
blocking the formation of peptidoglycan cross links
Which of the following antibiotics blocks the production of folic acid?
trimethoprim
True or false: Antibacterial drugs that inhibit nucleic acid synthesis are not as selectively toxic as drugs that target other bacterial processes.
true
True or false: 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
Which of the following antibiotics inhibits the transpeptidation reaction of peptidoglycan synthesis, but lacks a β-lactam ring in its structure?
vancomycin
Which mechanism of bacterial resistance to antibiotics (blue shapes) is illustrated inside the two red circles?
drug inactivation
The administration of a cocktail of anti-HIV agents at high dosages, called combination drug therapy, prevents the development of
drug resistance
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
The artemisinin mechanism of action appears to be that it _____ in Plasmodium-infected red blood cells that lead to altered hemoglobin catabolism and damage to the electron transport chain.
forms reactive oxygen intermediates
The tetracycline antibiotics are characterized by a _____.
four ring structure with various side chains attached
inhibitors are a category of drugs that block HIV entry into host cells.
fusion
As a general rule, the ___ (greater/smaller) therapeutic index, then the better the antimicrobial agent.
greater
In the Kirby-Bauer assay pictured here, the bacterial strain is _____.
growing over most of the surface of the plate
The oxazolidinones have a chemical structure featuring a _____.
heterocyclic five-membered ring
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
Bacteria sensitive to penicillin are killed as a result of osmotic___ .
lysis, or pressure
Many antifungal agents disrupt _____ synthesis.
membrane
Antiprotozoan drugs are NOT known to target which of the following?
membrane synthesis
The acronym "MRSA" stands for___ -resistant Staphylococcus aureus.
methicillin
Amoebic dysentery is usually treated with ________.
metronidazole
The concentration of drug necessary to prevent the growth of a pathogen is called the _____.
minimal inhibitory concentration
The concentration of drug necessary to kill a pathogen is called the _____.
minimal lethal concentration
What information do you get from the Etest that you do not get from the Kirby-Bauer test?
minimum inhibitory concentration
The dilution susceptibility test can be used to determine
minimum lethal concentration minimum inhibitory concentration
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.
paul ehrlich
The mechanism of action of is three-fold: It inhibits the transpeptidase reaction in peptidoglycan biosynthesis, activates bacterial autolytic enzymes, and stimulates holins to form holes in the plasma membrane.
penicillin
The most critical component of the vancomycin molecule is the ________ portion of the glycoprotein, which is essential for the antimicrobial activity of the drug.
peptide portion
The structural component of the vancomycin molecule that is critical for antimicrobial activity is the ________.
peptide portion.
It is thought that penicillin blocks the bacterial enzymes that create crosslinks between polymers (strands) in the cell wall.
peptidoglycan
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
Which of the following is not a target of fluoroquinolone drugs?
DNA polymerase
The antiviral agents acyclovir and cidofovir are analogues of DNA nucleotides, and inhibit the process of _____.
DNA replication
Acyclovir blocks the activity of viral___,___ enzyme.
DNA, polymerase or herpes simplex
True or false: Both penicillins and semisynthetic penicillins are substrates for beta-lactamases.
False
True or false: The lower the therapeutic index, the better the chemotherapeutic agent is. True false question.
False
True or false: There are more antiprotozoan agents than antibacterial agents.
False
Select two examples of resistance to antibiotics due to inactivation of a drug.
The activity of beta-lactamase Addition of acetyl-CoA to chloramphenicol
The fluoroquinolone antibiotics are characterized by a fluorinated _______.
4-quinolone ring
The antimicrobial activity of chloramphenicol results from its binding to _____.
50S ribosomal subunit
The antimalarial drug _____ has its origins in traditional Chinese medicine, and is now an effective and inexpensive treatment.
artemisinin
Oxazolidinones are _____.
bacteriostatic
Macrolide antibiotics interfere with protein synthesis by binding to _____.
50s ribosomal subunit
The minimal___concentration is the level of an antimicrobial agent required to kill a targeted pathogen.
lethal
Which two of the following are NOT targets of antibacterial drugs that inhibit nucleic acid synthesis?
80S Ribosome Dihydrofolate reductase
The therapeutic index is the ratio of the _____.
toxic dose to therapeutic dose
The World Health Organization recommends a combination of a quinine drug and a derivative of which of the following compounds in the treatment of malaria?
Artemisinin
True or false: In the disk diffusion test, zone width is a measure of bacterial susceptibility.
True
Using this image, determine the MIC for this microbe-antibiotic combination.
0.064 μg/ml
Place the steps of the disk diffusion test in the correct order.
1. inoculated surface of Mueller-Hinton agar plate with bacteria. 2.Place antibiotic infused test disks onto agar surface 3. incubate plates 16-18 hours at 35 C 4. Measure zone of inhibition 5. Determine MLC-Plot zone diameter on MIC chart.
Place the following antimicrobial agents in the correct order of their development as pharmaceuticals (from earliest to latest).
1. salvarsan 2. sulfonamides 3. penicillin 4. streptomycin 5. tetracycline
What is the approximate concentration of antibiotic when the inhibitory zone diameter is 14 mm?
16 ug/ml
Select three examples of resistance to antibiotics that is due to an altered cellular target of the drug.
A change in the structure of 23S rRNA The terminal D-alanine of pentapeptide mutates to D-serine Alteration of an enzyme involved in folic acid synthesis
Intrinsic resistance to antibiotics could be due to which one of these?
A particular structural feature of the bacterial cell
Which two of the following statements regarding artemisinin are correct?
A semisynthetic artemisinin is an effective, inexpensive treatment for malaria. Artemisinin originally derived from traditional Chinese medicine.
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 of the following are broad spectrum antibiotics?
Amoxicillin Ampicillin
Which three of the following are commonly used to treat systemic mycoses?
Amphotericin B 5-Flucytosine Fluconazole
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.
Which two of the following characteristics apply to nucleoside reverse transcriptase inhibitors?
Are nucleoside analogs Produce faulty viral DNA
True or false: Trimethoprim is a synthetic antibiotic.
True
Which of the following is the mode of action of trimethoprim?
Blocks folic acid synthesis
Which two of the following characteristics apply to tamiflu?
Blocks release of new viruses from host. Inhibits neuraminidase.
Antimetabolites are classified as ________ and ________ drugs.
Broad spectrum drugs Bacteriostatic
Many new antimicrobial agents have been discovered in which two soil inhabitants?
Fungi Bacteria
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 2?
Chloramphenicol
Which three of these are strategies being used to minimize the spread of antibiotic resistance?
Computer modeling of potential drug targets Searching for antimicrobial-producing organisms Use of bacteriophage in clinical settings
The antiviral agents acyclovir and cidofovir are analogues of _____.
DNA nulceotides
Which two of the following characteristics apply to the antiprotozoan drug chloroquine?
DIsrupts plasmodial DNA Causes build up of toxic heme metabolites
Which two of the following are targets of antibacterial drugs that inhibit nucleic acid synthesis?
DNA Polymerase Topoisomerase
selective toxicity--> Therapeutic dose--> Toxic dose-->
Death or inhibition of pathogen with minimal damage to host Drug level required for treatment of an infection Level at which drug becomes poisonous to host
Which of the following is the mechanism of griseofulvin antifungal activity?
Disrupt mitotic spindle
If you were suffering from a bacterial infection, which of the five antibiotics tested here would you not want your physician to prescribe for clearing the infection?
E
Which antibiotic is ineffective against the bacterial strain on the plate?
E
This image illustrates the _____ to determine antibiotic susceptibility and MIC.
Etest
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
Which of the following antibiotics inhibits DNA replication?
Fluoroquinolones
Why are there fewer antifungal drugs than antibacterial drugs?
Fungal cells are more similar to human cells than bacterial cells.
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.
Which two of the following are used to treat superficial mycoses?
Griseofulvin Nystatin
Which of the following characteristics applies to antifungal drugs?
Have a low therapeutic index
Which two of the following characteristics do not apply to macrolide antibiotics?
Inhibits DNA replication Has a four ring structure
Which of the following is NOT a mode of action of chloroquine?
Interferes with protein synthesis
Which of the following characteristics does not apply to tetracycline?
Is bactericidal
Culture-based search for new antibiotics
Isolate environmental cultures and screen for antibiotic production Metagenomics search for new antibiotics matches Shotgun cloning of environmental DNA samples to screen for the production of antibiotics Rational drug design matches Computer modeling of the active site of enzymes specific to bacteria
Cidal--> Static-->
Kills the target Reversibly inhibits the growth of the target
Which of the following is NOT a side effect of aminoglycoside antibiotic use?
Liver damage
In the dilution susceptibility test, the lowest concentration of antibiotic that results in no growth of the test bacterium is the _____.
MIC
Which of the following are targets of antifungal agents?
Membrane synthesis
Which two of the following are targets of antiprotozoan agents?
Metabolic processes Nucleic acids
Which statement best describes the rationale behind combination drug therapy in HIV patients?
Minimizes the chance for drug resistance development
Which two of the following characteristics apply to antifungal agents?
Most are fungistatic Many are toxic to human cells
Members of the rifamycin class of antibiotics inhibit growth by binding to the enzyme _____.
RNA polymerase
Which two of the following characteristics apply to nonnucleoside reverse transcriptase inhibitors (NNRTIs)?
Selectively bind to reverse transcriptase Inhibit reverse transcriptase
Naturally occurring antibiotics that have been chemically modified by the addition of chemical groups are called antibiotics.
Semisynthetic
Which of the following are typical sources of antimicrobial agents?
Semisynthetic agents - chemically modified naturally occurring antibiotics Natural products of soil bacteria and fungus Synthetic agents - products of chemical reactions
Which two of the following characteristics apply to aminoglycosides?
Synthesis of abnormal proteins. Bind to 30S ribosomal subunit.
Which of the following is a broad spectrum antibiotic?
Tetracycline
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
The degree of selective toxicity can be expressed in terms of
Toxic dose Therapeutic dose
The therapeutic index is the ratio of the___ dose to the___ dose.
Toxic therapeutic
Which of the following is a synthetic antibiotic that interferes with the production of folic acid?
Trimethoprim
Which two of the following characteristics apply to the antiprotozoan drug metronidazole?
Used to treat amoebic dysentery Effective at eradicating anaerobic protozoans
Which two of the following statements about nitazoxanide are true?
Used to treat cryptosporidiosis Generates reactive nitrogen species
Which of the following is a narrow spectrum antibiotic?
Vancomycin
Which of the following is considered a "drug of last resort" when treating antibiotic resistant Staphylococcus aureus?
Vancomycin
Which of the following is NOT a class of broad spectrum antibiotics?
Vancomycins
A zone of inhibition is _____.
a clear ring around an antibiotic disk in the Kirby-Bauer assay
The HIV transmission reduction strategy termed PrEP involves _____.
a daily oral dose of two NRTIs
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
Identify the mechanism of bacterial resistance to antibiotics (blue shapes) that is illustrated in the diagram inside the red circle.
alteration of target
these belong to the
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) _____.
antimetablite
A(n)___ is an antimicrobial substance that antagonizes or blocks the function of a specific biochemical pathway. Listen to the complete question
antimetabolite
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
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
Antimetabolites are considered to be___ spectrum and bacteriostatic antibacterial drugs.
broad
Chloramphenicol is a___ spectrum antibiotic.
broad
The fluoroquinolone drugs that target both gram-negative and gram-positive bacteria are considered to be___ spectrum antibiotics.
broad
The sulfonamides inhibit the growth of a wide variety of bacteria and are classified as___ -spectrum drugs.
broad
The tetracyclines___ are spectrum antibiotics.
broad
Drugs that are effective against a wide variety of pathogens are called _____ drugs.
broad-spectrum
The most selective antibiotics in use target the bacterial___,___ .
cell wall
The most selective antibiotics target _____.
cell wall synthesis
The highest therapeutic index is found with antimicrobial drugs that target___,___ synthesis.
cell, wall
Which of the following antibiotics inhibit protein synthesis by binding to the 50S ribosomal subunit?
chloramphenicol oxazolidinones 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
Upon phosphorylation, the antiviral drug acyclovir inhibits viral _____.
dNA polymerase
The artemisinin mechanism of action appears to be that it forms reactive oxygen intermediates in Plasmodium-infected red blood cells that lead to _____.
damage to the electron transport chain altered hemoglobin catabolism
In the disk diffusion test, zone-width is influenced by
diffusion rate of antibiotic, solubility of antibiotic, initial concentration of antibiotic.
The Kirby-Bauer test is the most commonly used type of _______.
disk diffusion test
Griseofulvin inhibits fungal cell division by _____
disrupting the mitotic spindle
Adenine arabinoside, found in the vidarabine ointment that is used to treat herpes infections and shingles, interferes with the synthesis of viral.
dna
Treatment of HIV infected cells with nucleoside reverse transcriptase inhibitors results in the production of faulty viral
dna
Treatment of HIV infected cells with nucleoside reverse transcriptase inhibitors results in the production of faulty viral .
dna
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
Select the mechanism of bacterial resistance to antibiotics (blue shapes) that is illustrated inside the red circle.
efflux pump
Methods to test bacterial isolates for drug resistance include _____.
enzyme detection kits with a chromophore, Polymerase chain reaction
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.
eukaryote
True or false: Most antifungal agents are fungicidal.
false
True or false: The macrolide antibiotics are bactericidal.
false
The___ are a family of synthetic antibacterial drugs that contain a fluorinated 4-quinolone ring.
fluoroquinolone
Sulfonamides disrupt the synthesis of___ acid, a precursor of purines.
folic
Sulfonamides disrupt the synthesis of___ acid, a precursor of purines. Listen to the complete question
folic
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
In the dilution susceptibility test, the minimum___ concentration is the lowest concentration of antibiotic that results in no growth after incubation.
inhibitory
The minimal___ concentration is the level of an antimicrobial agent required to stop the growth of a targeted pathogen.
inhibitory
Both minimum concentration and minimum concentration can be determined using the dilution susceptibility test.
inhibitory, lethal
Which statement about the antiprotozoan activity of clindamycin and paromomycin is true?
interfere with protein synthesis
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
Semisynthetic macrolide derivatives are known as _____.
ketolides
The term bactericidal means that the antimicrobial agent___ bacteria, and bacteriostatic means that it reversibly___ the growth of the bacteria.
kills, inhibits
William___ and A. W.___ developed a disk diffusion test that bears their names and is still in widespread use today.
kirby, Bauer
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 cephalosporin molecule is the β-___ ,___ which is essential for the antimicrobial activity of the drug.
lactam ring
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
The two newest classes of β-lactam drugs are
monobactams carbapenems
Penicillin G, penicillin V, and methicillin are___ spectrum antibiotics.
narrow
Vancomycin is a___ spectrum antibiotic.
narrow
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
The antiprotozoan agent nitazoxanide generates reactive___ species in Cryptosporidium.
nitrogen
The ultimate result of penicillin treatment of sensitive bacteria is cell-death resulting from ______.
osmotic lysis
In protozoans, the aminoglycoside antibiotics clindamycin and paromomycin interfere with the normal function of the ______.
ribosome
Members of the _____ class of antibiotics inhibit growth by binding to the enzyme RNA polymerase.
rifamycin
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
Antifungal agents that contain azoles inhibit___ synthesis and disrupt fungal membrane permeability.
sterol
Azoles are antifungal drugs that block _____ synthesis.
sterol
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.
substrate
The class of antibiotics that are structural analogues of p-aminobenzoic acid is the _____.
sulfonamides
Griseofulvin and nystatin are used to treat___ mycoses.
superficial
Toenail fungus and thrush are classified as superficial mycoses.
superficial
Toenail fungus and thrush are classified as___ mycoses.
superficial
An inhibitory zone diameter of 22 mm would indicate that this organism is _____ to this hypothetical drug.
susceptible
On this Petri dish showing the interaction of two microorganisms, the organism indicated by the letter A is _____.
susceptible to compounds produced by organism B
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
Due to the similarities of human and fungal cells, most antifungal drugs have a low___ index.
therapeutic
The semisynthetic penicillins nafcillin, oxacillin, and methicillin are more difficult for β-lactamase enzymes to degrade because _____.
they have bulkier side chains than natural penicillin
The HIV transmission reduction strategy termed PrEP is targeted to _____.
those with HIV-infected sexual partners
The fluoroquinolones disrupt DNA replication and repair by targeting which two enzymes?
topoisomerase DNA gyrase
A clear area that forms around an antibiotic disk after incubation with a bacterial strain is called a of inhibition.
zone
The structural component of the cephalosporin molecule that is critical for antimicrobial activity is the _________.
β-lactam ring
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