Microbiology Chapter 10

Which of the following is NOT associated with the work of Paul Ehrlich? sulfanilamide the concept of the "magic bullet" arsenic compounds the concept of chemotherapy

Which of the following is NOT a direct mode of action of antimicrobial drugs? inhibition of cell wall synthesis inhibition of protein synthesis inhibition of nucleic acid synthesis inhibition of flagella formation

Which of the following is NOT a beta-lactam antibiotic? methicillin vancomycin cephalothin penicillin G

Clavulanic acid could be used to protect which of the following antibiotics in a drug formulation? penicillin sulfanilamide bacitracin erythromycin

Which of the following is NOT a type of side effect exhibited by antimicrobial drugs? allergic reactions disruption of normal microbiota inhibition of host cellular enzymes damage to liver or kidney tissue

Which of the following is NOT associated with microbial mechanisms of resistance? denaturation of proteins porins MfpA protein beta-lactamases

Why is penicillin regarded as the first true antibiotic? Ehrlich's arsenic-based compounds were produced after the discovery and mass production of penicillin. It is effective against a wide variety of bacteria. The sulfonamides were not effective in treating any bacterial infections. It is produced naturally by the fungus Penicillium.

An antimicrobial drug that blocks the transport of NAG and NAM from the cytoplasm is targeting which of the following cellular processes? cytoplasmic membrane synthesis protein synthesis nucleic acid synthesis cell wall synthesis

__________ cells would be expected to be the most susceptible to the action of polyene drugs such as amphotericin B, while __________ cells would be the least susceptible. Bacterial; human Fungal; human Fungal; bacterial Bacterial; fungal

Which of the following is NOT a possible side effect of antimicrobial therapy? allergies disruption of normal microbiota toxicity resistance

Which of the following activities can be shown to increase resistance among microbial populations? developing second- and third-generation versions of antimicrobial drugs taking an antimicrobial drug for the entire prescribed time taking antibacterial drugs for viral infections taking a combination of antimicrobial drugs

Describe the administration route of the chemotherapeutic agent on the curve. Oral Intramuscular Continuous

An antimicrobial disk on a Kirby-Bauer plate that shows no zone of inhibition indicates that the microbe being tested is __________ to the drug. susceptible synergistic intermediate resistant

A particular microbe gains resistance to gentamicin. You might also expect this microbe to exhibit resistance against __________. streptomycin vancomycin clindamycin chloramphenicol

Why is the drug actinomycin used only in research applications or in the treatment of cancer? because it causes severe allergic reactions in most patients because it is not a very effective drug because it cannot be given orally, making it difficult to administer to patients because it is active against both prokaryotic and eukaryotic cells

If a particular bacterial species is resistant to beta-lactam antibiotics, which of the following might you expect to find inside the bacterial cells? porins ergosterol resistance pumps R plasmids

If the MBC for a particular drug is 16 μg/ml, which of the following serial dilutions of the drug is likely to be the MIC? 1.6 μg/ml 8 μg/ml 24 μg/ml 32 μg/ml

Which of the following antimicrobial drugs would likely be useful to treat a staphylococcal infection? erythromycin praziquantel isoniazid streptomycin

The following molecules are involved in the biosynthetic pathway that leads to the formation of DNA and RNA; what is their correct sequence in this pathway? a. PABA b. tetrahydrofolic acid c. purine and pyrimidine nucleotides d. dihydrofolic acid

Why do antimicrobial agents active against mycobacteria have to be administered for months or years rather than the typical 10-30 days prescribed to treat other infections? The only available agents are relatively ineffective drugs. Mycobacteria reproduce very slowly. They are too toxic to be used on a more rapid administration schedule. Mycobacteria do not have cell walls.

Put the following routes of administration in order, from the route that results in the highest concentration of drug in the bloodstream to the route that results in the lowest concentration: a. topical b. intravenous c. oral d. intramuscular

Prokaryotes contain _____ ribosomes. 50S 30S 70S 80S

Antimicrobial drugs are selectively toxic. This means _____. the drugs are reactive within a specific part of the patient's anatomy (for example, the inner ear) the drugs will not have toxic effects on a patient the drugs will affect only a particular type of pathogen the drugs are more toxic to the pathogens than to the patient

The tRNA molecule holding a growing polypeptide chain is at the _____. P site A site 50S site E site

Which category of antimicrobial drug works by changing the shape of a ribosome? chloramphenicol oxazolidinones aminoglycosides tetracyclines

Which category of antimicrobial drug essentially acts to stall a ribosome as it reads mRNA? chloramphenicol antisense nucleic acids macrolides tetracyclines

Chloramphenicol blocks the action of the large (50S) subunit. This essentially _____. prevents a large subunit from attaching to a small subunit prevents the formation of peptide bonds prevents the attachment of tRNA to a ribosome changes the shape of the large subunit

Which antimicrobial drugs affect the structure of the ribosome itself? macrolides and antisense nucleic acids aminoglycosides, chloramphenicol, and lincosamides aminoglycosides, antisense nucleic acids, and oxazolidinones tetracyclines and oxazolidinones

Which category of drug is complementary to mRNA of the pathogen? macrolides tetracyclines antisense nucleic acids oxazolidinones

What is meant by selective toxicity? Chemotherapeutic agents should work on many different targets on a pathogen. Chemotherapeutic agents should work on certain types of pathogens. Chemotherapeutic agents should have only one mode of action. Chemotherapeutic agents should act against the pathogen and not the host.

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug? The drugs also work against DNA gyrase. They are less expensive that other chemotherapeutic agents. Bacteria are especially sensitive to these compounds. Humans and other animal hosts lack peptidoglycan cell walls.

Why is polymyxin only used on the skin? It has no effect on bacteria that live in the GI tract. It is sensitive to degradation by acid, making oral delivery unsuitable. It can disrupt the metabolic pathways found in humans. It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

Quinolones and fluoroquinolones act against what bacterial target? Cell membranes DNA gyrase Cell walls Metabolic pathways unique to bacteria Bacterial ribosomes

Why is it difficult to find good chemotherapeutic agents against viruses? Viruses are not cells, and therefore not sensitive to such compounds. Viruses infect both bacteria and human cells. Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected. There is no effective way to deliver the drug to the virus.

Certain cancer cells have ABC transport molecules at the cell surface. These transporters use energy from ATP to move chemotherapeutic agents out of the cell. Which of the following do you think these transporters are most closely related to? altered porins conjugation pilus membrane pumps beta-lactamase

A new bacterial molecule is discovered. This molecule binds to an antibiotic and facilitates the binding of a phosphate group, thus inactivating the antibiotic. Which category best describes the mechanism of antibiotic resistance conferred by this molecule? altered porins bacterial enzymes rapid efflux of the antibiotic conjugation

Which antibiotic is overcome by beta-lactamases? Tetracycline Sulfonamide Penicillin Tetracycline, Penicillin, and Sulfonamide are all affected by beta-lactamase.

How might efflux pumps increase antibiotic resistance in bacteria? Resistant bacteria may have a greater number of efflux pumps on their cell surfaces. Some bacteria can decrease the specificity of their efflux pumps, increasing the number of different antibiotics the pumps can eliminate. Some bacteria can change the chemical structure of the antibiotic. Efflux pumps can never be modified to increase antibiotic resistance. Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.

Bacteria that are resistant to sulfonamide have enzymes that have a greater affinity for what? PABA Sulfonamide Tetrahyrdrofolic acid Tetracycline

Why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug? The efflux pumps would not stop penicillin from blocking metabolic pathways. There are fewer efflux pumps on the cell membrane. The cell membrane is the target of penicillin. Penicillin disrupts the cell wall, which is located outside of the cell membrane.

Membrane transport proteins are required for which mode(s) of antibiotic resistance? Modification of a porins Beta-lactamases Modification of a metabolic enzyme Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins. Efflux pumps

What is meant when a bacterium is said to become "resistant" to an antibiotic? The antibiotic kills or inhibits the bacterium. The antibiotic is metabolized by the bacterium, providing more energy for growth of the cell. The bacterium is neither killed nor inhibited by the antibiotic. The antibiotic mutates in a way that benefits the bacterium.

When a patient is treated with antibiotics, __________. mutations occur in all of the bacterial cells sensitive bacterial cells multiply uncontrollably the drug will kill or inhibit the growth of all of the sensitive bacterial cells the drug will kill or inhibit the growth of all of the resistant bacterial cells mutations will occur in the sensitive bacterial cells, but not in the resistant bacterial cells

The process of acquiring antibiotic resistance by means of bacteriophage activity is called transduction. R-plasmid acquisition. point mutation. transformation.

Which of the following mutations would not result in antibiotic resistance? Missense mutation Nonsense mutation Silent mutation Frameshift insertion Frameshift deletion

R-plasmids are most likely acquired via... (check all that apply) transformation. translation. transduction. bacterial conjugation.

Why do the beta-lactam drugs affect bacteria but NOT human cells?

A drug such as imipenem is chemically modified from penicillin. What are non-natural drugs developed from natural drugs called?

Why would beta-lactam drugs typically be considered more active against Gram-positive bacteria and less so against Gram-negative bacteria?