Microbiology Chapter 14

True

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

False

(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.

False

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

True

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

False

(T/F) β-lactamases can degrade vancomycin.

​B. semisynthetic

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

Neuraminidase inhibitors

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

Etest: used to determine MIC because it is a combination of Kirby-Bauer disk diffusion and dilution method test However the MBC cannot be determined by the Etest unlike macrobroth and microbrorh dilutions

Can an Etest be used to find the MBC of a drug? Explain.

HIV is a virus with complex life cycles: -targets CD4-postive white blood cells (immune system) -is a retrovirus - reverse transcriptase lacks proofreading activity and allows mutations and rapid development for antiviral drug resistance

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

-diameter of the zone of inhibition (in mm) is compared to a standardized chat and that determine the susceptibility/resistance of the bacterial pathogen to the drug

How is the information from a Kirby-Bauer disk diffusion test used for the recommendation of the clinical use of an antimicrobial drug?

Rifamycins: functions by blocking RNA polymerase activity in bacteria, RNA polymerase enzymes in bacteria are different from those in Eukaryotes, providing selective toxicity against bacterial cells

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

A.diameter

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

-inhibits ATP formation under anaerobic conditions -inhibits oxidative phophorylation in mitochondria of targeted pathogen -non absorbable allows for high localized intestinal concentration -starves paralysis and death of worm

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?

Prokaryotic

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

Nasal

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

Clostridium difficile

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

Actinomycetes

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

Etest

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

D. in a localized population.

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.

-before finishing prescription patients feel better and think they can stop taking it -they will get sick again and can build resistance to the treatment

Too often patients will stop taking antimicrobial drugs before the prescription is finished. What are factors that cause a patient to stop too soon, and what negative impacts could this have?

MIC: the lowest concentration of drug that inhibits the visible bacterial growth MBC: the lowest drug concentration that kills>99.9% of the starting inoculum

What is the difference between MIC and MBC?

MDR's: carry one or more resistance mechanism=resistance to multiple antimicrobials Cross resistance: a single resistance mechanism refers resistance to multiple antomicrobial drugs

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

-It was found to work after screening 600 arsenic containing compounds, remedy for the disease in humans Resulted in a now common strategy for discovery of new antibmicrobial agents

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

-targets variety of bacterial pathogens(g+/-), empiric therapy for potential pathogens, polymicrobic infections, prophylactic preventions of infections, treat infection when narrow spectrum drug fails becuase of drug resistance

When is using a broad-spectrum antimicrobial drug warranted?

-age, weight(mass), patient history regarding how the drugs will be metabolized and eliminated

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

Mold, plant derived medicines

Where do antimicrobials come from naturally? Why?

​C. treatment of strep throat caused by culture identified Streptococcus pyogenes

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

A. sulfanilamide

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

C. nalidixic acid

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

​C. short-term use of narrow-spectrum antimicrobials

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

​A. tetracyclines

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

​B. avermectins

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

D. soil

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

​​D. azidothymidine

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

​A. artemisinin

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

​B. glycopeptides

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

​C. cholesterol

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

​C. drug inactivation

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

A. efflux pump

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

​​D. efflux pump

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

A.oral

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

C. Kirby-Bauer disk diffusion test

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

​​D. selective toxicity

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

A. MRSA

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

-those who understand soul microorganisms throughly and have access to more than just a standar laboratory methods or culturing antibiotics

Who should be responsible for discovering and developing new antibiotics? Support your answer with reasoning.