MicroBio Ch. 14 Review Questions

Niclosamide is insoluble and thus is not readily absorbed from the stomach into the bloodstream. How does the insolubility of niclosamide aid its effectiveness as a treatment for tapeworm infection?

- is not absorbed from the gastrointestinal tract, thus it can achieve high localized intestinal concentrations in patients.

When prescribing antibiotics, what aspects of the patient's health history should the clinician ask about and why?

- mass - allergies - liver/kidney disfunctions - intervals between doses - any medications they are currently on.

What bacterial structural target would make an antibacterial drug selective for gram-negative bacteria? Provide one example of an antimicrobial compound that targets this structure.

- monobactam - inhibit the transpeptidase activity of penicillin-binding proteins - only targets gram-negative bacteria

If human cells and bacterial cells perform transcription, how are the rifamycins specific for bacterial infections?

- narrow spectrum - activity against gram-positive and limited numbers of gram-negative bacteria - also active against Mycobacterium tuberculosis

When is using a broad-spectrum antimicrobial drug warranted?

- polymicrobic infections - invasive/surgical procedures - infections when narrow-spectrum drugs fail - broad-spectrum drugs will attack bad and good bacteria. - increases risk of "super-infection"

How does the biology of HIV necessitate the need to treat HIV infections with multiple drugs?

1st - HIV targets white blood cells, need them for normal immine response to infection 2nd - HIV is retrovirus, it converts its RNA genome into a DNA copy that integrates into the host cell's genome. This hides it inside the host cell DNA 3rd - HIV reverse transcriptase lacks proofreading activity and introduces mutation that allow rapid development of antiviral drug resistance.

In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation. A. diameter B. microbial population C. circumference D. depth

A

Which of the following antimicrobial drugs is synthetic? A. sulfanilamide B. penicillin C. actinomycin D. neomycin

A

Which of the following does not bind to the 50S ribosomal subunit? A. tetracyclines B. lincosamides C. macrolides D. chloramphenicol

A

Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells? A. artemisinin B. amphotericin b C. praziquantel D. pleconaril

A

Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes? A. efflux pump B. target mimicry C. target modification D. target overproduction

A

Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection? A. oral B. intravenous C. topical D. parenteral

A

Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota? A. MRSA B. VRE C. CRE D. ESBL-producing bacteria

A

The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.

Actinomycetes

A scientist discovers that a soil bacterium he has been studying produces an antimicrobial that kills gram-negative bacteria. She isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. When she tests the antimicrobial properties of this new version, she finds that this antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following? A. resistant B. semisynthetic C. synthetic D. natural

B

Which of the following combinations would most likely contribute to the development of a superinfection? A. long-term use of narrow-spectrum antimicrobials B. long-term use of broad-spectrum antimicrobials C. short-term use of narrow-spectrum antimicrobials D. short-term use of broad-spectrum antimicrobials

B

Which of the following drug classes specifically inhibits neuronal transmission in helminths? A. quinolines B. avermectins C. amantadines D. imidazoles

B

Which of the following is not a type of β-lactam antimicrobial? A. penicillins B. glycopeptides C. cephalosporins D. monobactams

B

Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug? A. treatment of a polymicrobic mixed infection in the intestine B. prophylaxis against infection after a surgical procedure C. treatment of strep throat caused by culture identified Streptococcus pyogenes D. empiric therapy of pneumonia while waiting for culture results

C

Which of the following antimicrobials inhibits the activity of DNA gyrase? A. polymyxin B B. clindamycin C. nalidixic acid D. rifampin

C

Which of the following is not an appropriate target for antifungal drugs? A. ergosterol B. chitin C. cholesterol D. β(1→3) glucan

C

Which of the following resistance mechanisms describes the function of β-lactamase? A. efflux pump B. target mimicry C. drug inactivation D. target overproduction

C

Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe? A. Etest B. microbroth dilution test C. Kirby-Bauer disk diffusion test D. macrobroth dilution test

C

The utility of an antibiogram is that it shows antimicrobial susceptibility trends A. over a large geographic area. B. for an individual patient. C. in research laboratory strains. D. in a localized population.

D

Which of the following has yielded compounds with the most antimicrobial activity? A. water B. air C. volcanoes D. soil

D

Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV? A. acyclovir B. ribavirin C. adenine-arabinoside D. azidothymidine

D

Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials? A. drug modification B. target mimicry C. target modification D. efflux pump

D

Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host? A. mode of action B. therapeutic level C. spectrum of activity D. selective toxicity

D

T/F If drug A produces a larger zone of inhibition than drug B on the Kirby-Bauer disk diffusion test, drug A should always be prescribed.

F

T/F Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.

F

T/F β-lactamases can degrade vancomycin.

F

Why was Salvarsan considered to be a "magic bullet" for the treatment of syphilis?

He wanted something that was capable of killing infectious microbes without harming the patient

What is the difference between MIC and MBC?

MIC - the lowest concentration of drug that inhibits visible bacterial growth - determined by examining the tubes to find the lowest drug concentration that inhibits visible growth; this is observed as turbidity (cloudiness) in the broth. MBC - the lowest drug concentration that kills ≥99.9% of the starting inoculum - cannot be determined with the Etest.

What is the difference between multidrug resistance and cross-resistance?

Multidrug resistance - known as "superbugs" and carry one or more resistance mechanism(s), making them resistant to multiple antimicrobials cross-resistance - a single resistance mechanism confers resistance to multiple antimicrobial drugs.

T/F Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.

T

T/F The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.

T

The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.

clostridium difficile

The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.

etest

Where do antimicrobials come from naturally? Why?

extracted from soil, mold, and fungi.

Why does the length of time of antimicrobial treatment for tuberculosis contribute to the rise of resistant strains?

it gives the disease time to build immunity against the antimicrobial treatments. - The development of resistance in these strains often results from the incorrect use of antimicrobials for tuberculosis treatment, selecting for resistance.

Staphylococcus aureus, including MRSA strains, may commonly be carried as a normal member of the ________ microbiota in some people.

nasal

Antiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by preventing viral escape from host cells are called ________.

neuraminidase

Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.

prokaryotic