Microbiology Chapter 9

Macrolide antibiotics interfere with protein synthesis by binding to _____. Multiple choice question. DNA polymerase 30S ribosomal subunit 50S ribosomal subunit ATP synthase

50S ribosomal subunit

Intrinsic resistance to antibiotics could be due to which one of these? Multiple choice question. A mutation that alters the cellular binding site of the drug. Acquisition of a plasmid that codes for beta-lactamase. A particular structural feature of the bacterial cell A change in the genome of a bacterium.

A particular structural feature of the bacterial cell

Which of these mutations would be most likely to confer resistance to the antibiotic penicillin? Multiple choice question. Alteration of the terminal D-alanine in the pentapeptide of peptidoglycan Changing the structure of 23S rRNA Acquisition of beta-lactamase activity Altered activity of enzymes involved in folic acid synthesis

Acquisition of beta-lactamase activity

Which of these mutations would be most likely to confer resistance to the antibiotic penicillin? Multiple choice question. Changing the structure of 23S rRNA Acquisition of beta-lactamase activity Altered activity of enzymes involved in folic acid synthesis Alteration of the terminal D-alanine in the pentapeptide of peptidoglycan

Acquisition of beta-lactamase activity

Select two examples of resistance to antibiotics due to inactivation of a drug. Multiple select question. Alteration of an enzyme involved in folic acid synthesis Reason: This is an alteration of the target of the drug, not the drug itself. Addition of acetyl-CoA to chloramphenicol A change in the structure of 23S rRNA Reason: This is an alteration of the target of the drug, not the drug itself. The terminal D alanine of pentapeptide mutates to D-serine Reason: This is an alteration of the target of the drug, not the drug itself. The activity of beta-lactamase

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

Which of these mutations would be most likely to confer resistance to the antibiotic vancomycin? Multiple choice question. Changing the structure of 23S rRNA. Altered activity of enzymes involved in folic acid synthesis. Acquisition of acetyltransferase activity. Alteration of the terminal D-alanine in the pentapeptide of peptidoglycan.

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? Multiple choice question. Alteration of the terminal D-alanine in the pentapeptide of peptidoglycan Altered activity of enzymes involved in folic acid synthesis Changing the structure of 23S rRNA Acquisition of beta-lactamase activity

Altered activity of enzymes involved in folic acid synthesis

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

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

Many new antimicrobial agents have been discovered in which two soil inhabitants? Multiple select question. Archaea Bacteria Protists Fungi Worms

Bacteria Fungi

Antimetabolites are classified as ________ and ________ drugs. Multiple select question. Bactericidal Broad spectrum drugs Bacteriostatic Narrow spectrum drugs

Broad spectrum drugs Bacteriostatic

Which two of the following are NOT targets of antibacterial drugs that inhibit nucleic acid synthesis? Multiple select question. Dihydrofolate reductase DNA Polymerase Topoisomerase 80S Ribosome

Dihydrofolate reductase 80S Ribosome

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.

Ehrlich

Which of the following conditions has a significant contribution to the maintenance of drug resistant genes in a bacterial population? Multiple choice question. Exposure of bacteria to the drug Formation of biofilms Exposure of bacteria to ultraviolet radiation Immune deficiencies of the host

Exposure of bacteria to the drug

True or false: Both penicillins and semisynthetic penicillins are substrates for beta-lactamases. True false question. True False

False

Which of the following antibiotics inhibits DNA replication? Multiple choice question. Chloramphenicol Trimethoprim Tetracyclines Fluoroquinolones

Fluoroquinolones

Which three of the following are consistent with current strategies to prevent the emergence of drug resistance? Multiple select question. High dosages to kill susceptible and mutant microbes Strict control of broad-spectrum drug usage Combination drug therapy Limit antibiotic use to hospital environments only Use antibiotics only until symptoms begin to fade Perform susceptibility testing on every patient

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

Which statement is NOT consistent with current strategies for limiting the development of antibiotic resistance? Multiple choice question. High dosages to kill susceptible and mutant microbes Increased usage of antibiotics in farm animal feed Simultaneous administration of multiple drugs Restriction of of broad-spectrum drug usage

Increased usage of antibiotics in farm animal feed

Which of the following characteristics does not apply to tetracycline? Multiple choice question. Is a broad spectrum antibiotic Inhibits protein synthesis Has a four ring structure Is bactericidal

Is bactericidal

Which of the following characteristics does not apply to tetracycline? Multiple choice question. Is a broad spectrum antibiotic Inhibits protein synthesis Is bactericidal Has a four ring structure

Is bactericidal

In the dilution susceptibility test, the lowest concentration of antibiotic that results in no growth of the test bacterium is the _____. Multiple choice question. MLC MIC TIC TLC

MIC

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. Multiple choice question. Robert Koch Paul Ehrlich Joseph Lister John Snow

Paul Ehrlich

Members of the rifamycin class of antibiotics inhibit growth by binding to the enzyme _____. Multiple choice question. topoisomerase DNA polymerase RNA polymerase DNA gyrase

RNA polymerase

In the disk diffusion test, zone-width is influenced by Multiple select question. Solubility of antibiotic Initial concentration of antibiotic Bacterial size Diffusion rate of antibiotic Rate of bacterial growth

Solubility of antibiotic Initial concentration of antibiotic Diffusion rate of antibiotic

Which two of the following characteristics apply to aminoglycosides? Multiple select question. Inhibit cell wall synthesis Synthesis of abnormal proteins Bind to 30S ribosomal subunit Often a drug of last resort Inhibit gyrase activity

Synthesis of abnormal proteins Bind to 30S ribosomal subunit

Which two of the following characteristics apply to aminoglycosides? Multiple select question. Synthesis of abnormal proteins Inhibit gyrase activity Bind to 30S ribosomal subunit Inhibit cell wall synthesis Often a drug of last resort

Synthesis of abnormal proteins Bind to 30S ribosomal subunit

Which of the following is a broad spectrum antibiotic? Multiple choice question. Streptomycin Tetracycline Ciprofloxacin Methicillin

Tetracycline

Select two examples of resistance to antibiotics due to inactivation of a drug. Multiple select question. 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 The activity of beta-lactamase Addition of acetyl-CoA to chloramphenicol

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

Select three examples of resistance to antibiotics that is due to an altered cellular target of the drug. Multiple select question. The terminal D-alanine of pentapeptide mutates to D-serine Addition of acetyl-CoA to chloramphenicol Alteration of an enzyme involved in folic acid synthesis The activity of beta-lactamase 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 A change in the structure of 23S rRNA

Which two of the following are targets of antibacterial drugs that inhibit nucleic acid synthesis? Multiple select question. Dihydrofolate reductase DNA Polymerase 80S Ribosome Topoisomerase

Topoisomerase DNA Polymerase

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

True

Select two examples of alternative metabolic pathways used by bacteria to resist the activity of an antibiotic. Multiple select question. Change D-alanine in the pentapeptide of peptidoglycan Reason: This is an example of altering the target. Use preformed folic acid instead of synthesizing it Hydrolyze penicillins Reason: This is an example of drug inactivation. Remove drug from cell using an efflux pump Increase folic acid production

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

Select two examples of alternative metabolic pathways used by bacteria to resist the activity of an antibiotic. Multiple select question. Hydrolyze penicillins Use preformed folic acid instead of synthesizing it Change D-alanine in the pentapeptide of peptidoglycan Remove drug from cell using an efflux pump Increase folic acid production

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

A zone of inhibition is _____. Multiple choice question. the space between a bacterial inner and outer membrane a clear ring around an antibiotic disk in the Kirby-Bauer assay a zone around a bacterial colony that is resistant to antibiotic the laboratory space around the flame where contamination is unlikely to occur

a clear ring around an antibiotic disk in the Kirby-Bauer assay

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? Multiple choice question. Acquired Inherent

acquired

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? Multiple choice question. Inherent Acquired

acquired

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

Many efflux pumps involved in bacterial resistance to antibiotics pump the drug from the cell as protons enter; this is what type of transporter? Multiple choice question. uniport antiport symport

antiport

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

bacteria and fungi

Vancomycin has the same target as β-lactam antibiotics, the transpeptidation reaction in peptidoglycan synthesis, but it differs in that it _____. Multiple choice question. speeds up the reaction rather than inhibiting it binds to the enzyme's substrate binds to the enzyme's active site binds to the enzyme's allosteric site

binds to the enzyme's substrate

Fluoroquinolones are antibacterial drugs that _____. Multiple choice question. block folic acid synthesis block nucleic acid synthesis block membrane synthesis block cell wall synthesis

block nucleic acid synthesis

Penicillin disrupts cell wall formation by _____. Multiple choice question. hydrolyzing the peptidoglycan chains binding to the 30S ribosomal subunit blocking the formation of peptidoglycan cross links repressing bacterial genes for cell wall synthesis

blocking the formation of peptidoglycan cross links

Penicillin disrupts cell wall formation by _____. Multiple choice question. repressing bacterial genes for cell wall synthesis blocking the formation of peptidoglycan cross links binding to the 30S ribosomal subunit hydrolyzing the peptidoglycan chains

blocking the formation of peptidoglycan cross links

Antimetabolites are considered to be ___________ spectrum and bacteriostatic antibacterial drugs.

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

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

The most selective antibiotics target _____. Multiple choice question. protein synthesis cell wall synthesis metabolic pathways nucleic acid synthesis

cell wall synthesis

Which two of the following antibiotics inhibit protein synthesis by binding to the 50S ribosomal subunit? Multiple select question. tetracyclines chloramphenicol macrolides oxazolidinones aminoglycosides

chloramphenicol macrolides

The drugs that target the cell wall have a high therapeutic index because human cells _____. Multiple choice question. have different sized ribosomes compared to microbes have different enzymes for cell wall synthesis are aerobic do not have cell walls

do not have cell walls

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

efflux

True or false: The lower the therapeutic index, the better the chemotherapeutic agent is. True false question. True False

false

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

folic

Sulfa drugs block ________ synthesis. Multiple choice question. cell wall folic acid protein membrane

folic acid

A drug that disrupts a microbial structure or function not found in host cells has a _____ therapeutic index. Multiple choice question. high moderate low

high

Sulfonamides have a high therapeutic index because _____. Multiple choice question. humans do not have the pathways inhibited by the drug they inhibit transcription, a cellular process not found in human cells they bind bacterial 70S ribosomes humans use a different biochemical pathway to synthesize folate

humans do not have the pathways inhibited by the drug

Sulfonamides have a high therapeutic index because _____. Multiple choice question. they bind bacterial 70S ribosomes they inhibit transcription, a cellular process not found in human cells humans do not have the pathways inhibited by the drug humans use a different biochemical pathway to synthesize folate

humans do not have the pathways inhibited by the drug

A consequence of the fact that humans do not synthesize folate but bacteria do is that _____. Multiple choice question. bacteria are less likely to become resistant to folate inhibitors of the folate pathway have a high therapeutic index humans are much more susceptible to the side effects of folate

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

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

intrinsic

Penicillin has a high therapeutic index because _____. Multiple choice question. resistance to it does not develop commonly its cellular target, peptidoglycan, is absent from host cells it is quite stable in stomach acid it is only mildly toxic to host cells

its cellular target, peptidoglycan, is absent from host cells

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

kills and inhibits

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

lactam

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

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

larger

In the absence of a drug, a population of drug-resistant bacteria should become _________ resistant to the drug. Multiple choice question. less more

less

Drugs that inhibit nucleic acid synthesis in bacteria are said to be ________. Multiple choice question. more selectively toxic no difference in toxicity less selectively toxic

less selectively toxic

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

lethal

The concentration of drug necessary to prevent the growth of a pathogen is called the _____. Multiple choice question. toxic dose minimal inhibitory concentration therapeutic index minimal lethal concentration

minimal inhibitory concentration

The concentration of drug necessary to kill a pathogen is called the _____. Multiple choice question. minimal lethal concentration LD50 therapeutic index minimal inhibitory concentration

minimal lethal concentration

What information do you get from the Etest that you do not get from the Kirby-Bauer test? Multiple choice question. minimum inhibitory concentration minimum lethal concentration whether the effect is static or cidal which antibiotic the organism is resistant to

minimum inhibitory concentration

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. Multiple choice question. broad-spectrum bacteriostatic bactericidal narrow-spectrum

narrow-spectrum

The most critical component of the vancomycin molecule is the ________ portion of the glycoprotein, which is essential for the antimicrobial activity of the drug. Multiple choice question. peptide sugar lipid

peptide

The structural component of the vancomycin molecule that is critical for antimicrobial activity is the ________. Multiple choice question. peptide portion imidazole ring cyclohexane ring β-lactam ring

peptide portion

The structural component of the vancomycin molecule that is critical for antimicrobial activity is the ________. Multiple choice question. peptide portion β-lactam ring imidazole ring cyclohexane ring

peptide portion

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

peptidoglycan

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

peptidoglycan or nam-nag

Erythromycin and other macrolide antibiotics interfere with bacterial __________ synthesis.

protein

Aminoglycosides interfere with _____. Multiple choice question. carbon metabolism protein synthesis nucleic acid synthesis cell wall synthesis

protein synthesis

Aminoglycosides interfere with _____. Multiple choice question. protein synthesis carbon metabolism cell wall synthesis nucleic acid synthesis

protein synthesis

Members of the _____ class of antibiotics inhibit growth by binding to the enzyme RNA polymerase. Multiple choice question. oxazolidinone tetracycline rifamycin fluoroquinolone

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 _____. Multiple choice question. broad spectrum metabolic antagonism narrow spectrum selective toxicity

selective toxicity

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

substrates

The semisynthetic penicillins nafcillin, oxacillin, and methicillin are more difficult for β-lactamase enzymes to degrade because _____. Multiple choice question. they are more acid-resistant than natural penicillin they have a sulfur atom in the β-lactam ring they have bulkier side chains than natural penicillin they do not have the β-lactam ring found in natural penicillin

they have bulkier side chains than natural penicillin

True or false: In the disk diffusion test, zone width is a measure of bacterial susceptibility. True false question.TrueFalse

true

True or false: The tetracyclines are bacteriostatic. True false question. True False

true

Which of the following antibiotics inhibits the transpeptidation reaction of peptidoglycan synthesis, but lacks a β-lactam ring in its structure? Multiple choice question. monobactam carbapenem vancomycin cephalosporin

vancomycin

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 penicillin molecule that is critical for antimicrobial activity is the _______. Multiple choice question. lactone ring cyclohexane ring β-pleated sheet β-lactam ring

β-lactam ring

The basis of penicillin resistance in bacteria is the ability to produce enzymes called penicillinases or _______. Multiple choice question. α-amylases acetyltransferases β-lactamases aminoglycosides

β-lactamases