Microbiology Chapter 20

Antimicrobials that kill microorganisms have the suffix -cidal. -static. -anti. -genic.

-cidal

Antimicrobials that inhibit the growth of microorganisms have the suffix -cidal. -static. -anti. -genic.

-static.

The minimum bactericidal concentration is the lowest concentration of a specific antimicrobial drug that kills _______ of a specific type of bacteria. 10% 50% 99.9% 100%

99.9%

Antimicrobials may produce a. allergic reactions. b toxic effects. c. suppression of normal flora. d. All of the choices are correct.

All of the choices are correct

Bacteria may become antibiotic resistant due to a. drug-inactivating enzymes. b. alteration in the target molecule. c. decreased uptake of the drug. d. increased elimination of the drug. e. All of the choices are correct.

All of the choices are correct

Which of the following groups of microorganisms produces antibiotics? a. Penicillium b. Streptomyces c. Bacillus d. All of the choices are correct. e. Penicillium AND Streptomyces

All of the choices are correct

The zone size obtained in the Kirby-Bauer test is influenced by the drug's a. size. b. stability. c. concentration. d. All of the choices are correct.

All of the choices are correct.

Which of the following drugs target peptidoglycan? a. penicillin b. cephalosporin c. vancomycin d. bacitracin e. All of the choices are correct.

All of the choices are correct.

Fluoroquinolones typically target a. ribosomes. b. penicillin-binding proteins. c. peptidoglycan. d. DNA gyrase.

DNA gyrase.

A commercial modification of the disk diffusion test is called the A test. B test. C test. D test. E test.

E test

One of the earliest researchers to explore the use of chemicals to kill microbial pathogens was Koch. Hooke. Fleming. Ehrlich.

Ehrlich

Broad-spectrum antibiotics have minimal effect on the normal flora. True False

False

Viruses are very effectively treated with antibiotics. True False

False

Penicillin was discovered by Koch. Hooke. Fleming. Ehrlich.

Fleming

The most effective form of penicillin is A. B. E. G.

G

In what clinical situation is it most appropriate to use a broad-spectrum antimicrobial? In an example of a pediatric otitis media (middle ear) infection. We can't properly test for the specific drug that would best eliminate the infection due to its location, so we use a broad-spectrum drug instead. In a case of viral meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don't have time to determine which drug will work best, because the patient will die in the meantime. In a case of bacterial meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don't have time to determine which drug will work best, because the patient will die in the meantime. In a case of Staphylococcus aureus skin infection. Since this microbe can be resistant to several types of drugs, we want to use one that has the broadest spectrum possible to treat this microbe-specific infection.

In a case of bacterial meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don't have time to determine which drug will work best, because the patient will die in the meantime.

Explain how using a combination of two antimicrobial drugs helps prevent the development of spontaneously resistant mutants. All drugs work synergistically with each other-that is, their combined effects are far greater than either could achieve individually. Two drugs together helps to eliminate microbes, even if they have developed spontaneous mutations that would confer upon them resistance to the drugs. It is highly unlikely that the microbe might spontaneously develop 2 specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the 2nd drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall. All drugs work antagonistically with each other-that is, their combined effects are far greater than either could achieve individually. Two drugs together helps to eliminate microbes, even if they have developed spontaneous mutations that would confer upon them resistance to the drugs. Drugs can also select for mutations that will enhance the activity of another drug. So, each of the paired drugs will help to select for spontaneous mutations that enhance the activity of the other drug in the pair.

It is highly unlikely that the microbe might spontaneously develop 2 specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the 2nd drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall.

Which test is used to determine the susceptibility of a microorganism to an antimicrobial? MIC MIB MLB Kirby-Bauer test

Kirby-Bauer test

Mycolic acids are targeted by isoniazid in the treatment of S. aureus. S. epidermidis. M. luteus. M. tuberculosis.

M. tuberculosis.

Compliance problems are leading to a large increase in antibiotic resistant strains of Streptococcus. Staphylococcus. Mycobacterium. Pseudomonas.

Mycobacterium

Which of the following bacteria have an innate resistance to penicillin? S. aureus S. epidermidis M. luteus Mycoplasma

Mycoplasma

Sulfonamides are similar in structure to DNA gyrases. LPS. ribosomes. PABA.

PABA

Why would co-administration of a bacteriostatic drug interfere with the effects of penicillin? Since most bacteriostatic drugs are produced from bacteria, but penicillin is produced from mold, the two drugs are incompatible with each other. A bacteriostatic drug produces interference in the ability of a bacterial cell to take in compounds from the outside environment. Penicillin must be taken in by the cell in order to have its effect, so this would directly inhibit it. Penicillin interferes with cell wall production/stabilization by cross-linking of peptidoglycan. As such, it only works when the cells are actively replicating and MAKING new peptidoglycan. A bacteriostatic drug works by shutting down replication, holding the cells 'static.' This would interfere with the mode of action required by the penicillin. The bacteriostatic drugs would bind directly to the penicillin, preventing both its uptake by the cell and its ability to perform its duty within the bacterial cell.

Penicillin interferes with cell wall production/stabilization by cross-linking of peptidoglycan. As such, it only works when the cells are actively replicating and MAKING new peptidoglycan. A bacteriostatic drug works by shutting down replication, holding the cells 'static.' This would interfere with the mode of action required by the penicillin.

The most common method of transfer of antimicrobial resistance is through the use of viruses. R plasmids. introns. exons.

R plasmids

The arsenic compound that proved highly effective in treating syphilis was called penicillin. sulfa. erythromycin. Salvarsan

Salvarsan

The first example of an antimicrobial drug synthesized in the laboratory was penicillin. sulfa. erythromycin. Salvarsan.

Salvarsan

Which is true of aminoglycosides? a. They are bacteriostatic. b. They irreversibly bind to the 30S ribosomal subunit. c. They block peptidoglycan synthesis. d. They are bactericidal. e. They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal

They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal

Antifungal drugs usually target the cell membrane. True False

True

Antimicrobial resistance can be due to spontaneous mutation or gene acquisition. True False

True

Antimicrobials that have a high therapeutic index are less toxic to the patient. True False

True

Beta-lactam drugs are only effective against growing bacteria. True False

True

Certain antimicrobials may be life-threatening. True False

True

Drugs that target peptidoglycan do not affect eukaryotes. True False

True

The MBC may be determined by an extension of the MIC. True False

True

The key characteristic of a useful antimicrobial is selective toxicity. True False

True

The major class(es) of antibiotics that inhibit protein synthesis is/are a. aminoglycosides. b. tetracyclines. c. macrolides. d. bacitracins. e. aminoglycosides, tetracyclines AND macrolides

aminoglycosides, tetracyclines AND macrolides

If drugs are less effective when taken together than when each is taken separately, they are called energetic. antagonistic. additive. synergistic.

antagonistic

The antimicrobials produced by some molds and bacteria are generally called insecticides. biocides. antiseptics. antibiotics.

antibiotics

Penicillin-binding proteins a. primarily function in the cell to bind to beta-lactam drugs. b. are enzymes. c. are involved in cell wall synthesis. d. inhibit non-growing bacteria. e. are enzymes AND are involved in cell wall synthesis.

are enzymes AND are involved in cell wall synthesis.

All members of the penicillin family have beta-lactam rings. alpha-lactam rings. phenolic rings. sulfanilic rings.

beta-lactam rings

Beta-lactamases a. bind to penicillin-binding proteins. b. bind to peptides. c. prevent the linking of glycan d. chains in peptidoglycan. e. break the beta-lactam ring.

break the beta-lactam ring

Antibiotics that affect various strains of Gram-positive bacteria and various strains of Gram-negative bacteria are called isolate usable. stress-induced. narrow-spectrum. broad-spectrum.

broad-spectrum

Antibiotics that are most likely to disrupt the normal flora are termed narrow-spectrum. broad-spectrum. targeted spectrum. semi-synthetic

broad-spectrum.

The use of Salvarsan and Prontosil to treat microbial infections were early examples of antibiotics. toxins. inhibitors. chemotherapy.

chemotherapy.

Folic acid is ultimately used in the synthesis of topoisomerases. proteins. DNA gyrases. sulfonamides. coenzymes.

coenzymes

Sulfonamides work as a. competitive inhibitors. b. noncompetitive inhibitors. c. ribosome-binding molecules. d. feedback inhibitors.

competitive inhibitors

The target of most antifungal drugs is a. the ribosome. b. nucleus. c. cholesterol. d. ergosterol. e. cholesterol AND ergosterol.

ergosterol

Sulfonamide and trimethoprim are both a. examples of metabolic inhibitors. b. folate inhibitors. c. protein synthesis inhibitors. d. inhibitors of cell wall synthesis. e. examples of metabolic inhibitors AND folate inhibitors.

examples of metabolic inhibitors AND folate inhibitors

The rate of elimination of an antimicrobial is expressed as its a. metabolic destructive rate. b. half-life. c. effective time. d. dosage rate.

half-life.

Drugs that are bacteriostatic a. kill bacteria. b. promote bacterial growth. c. inactivate bacterial spores. d. inhibit the growth of bacteria.

inhibit the growth of bacteria.

The diffusion bioassay a. determines the concentration of antimicrobial necessary to kill a bacteria. b. determines the concentration of antimicrobial necessary to inhibit growth of a bacteria. c. is similar in principal to the Kirby-Bauer test. d. determines the concentration of antimicrobial in a fluid. e. is similar in principal to the Kirby-Bauer test AND determines the concentration of antimicrobial in a fluid.

is similar in principal to the Kirby-Bauer test AND determines the concentration of antimicrobial in a fluid.

A high therapeutic index is a. more toxic to the patient. b. less toxic to the patient. c. has no effect on the patient. d. has no effect on the pathogen.

less toxic to the patient.

The lowest concentration of a drug that prevents growth of a microorganism is the a. infectious dose. b. lethal dose. c. effective dose. d. minimum inhibitory concentration

minimum inhibitory concentration

Inhibitors of protein synthesis typically key on a. peptidoglycan precursors. b. penicillin-binding proteins. c. ribosomes. d. porin proteins

ribosomes

An antibiotic made by microorganisms and modified by chemists is called anti-metabolic. catabolic. synthetic. semi-synthetic.

semi-synthetic

One of the earliest antimicrobials isolated from a bacterium was penicillin. ampicillin. Salvarsan. streptomycin.

streptomycin

Prontosil effectively acted on streptococci when the drug was split by enzymes to produce penicillin. sulfanilamide. erythromycin. Salvarsan.

sulfanilamide.

Drugs that are more effective when taken together are called energetic. antagonistic. subtractive. synergistic.

synergistic

Trimethoprim and sulfonamides have a(n) antagonistic effect. synergistic effect. energetic effect. subtractive.

synergistic effect

The toxicity of a given drug is expressed as the selective toxicity. biocide index. biostatic index. therapeutic index.

therapeutic index

Antiviral drugs may target a. uncoating. b. nucleic acid synthesis. c. viral assembly. d. viral ribosomes. e. uncoating, nucleic acid synthesis AND viral assembly.

uncoating, nucleic acid synthesis AND viral assembly