Micro lecture Ch. 14 - critical thinking questions
How is the information from a Kirby-Bauer disk diffusion test used for the recommendation of the clinical use of an antimicrobial drug?
- The zone of inhibition (in mm) is compared to a standardized chart that determine the susceptibility/resistance of the bacterial pathogen to the drug
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?
-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
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?
-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 inhibits ATP formation under anaerobic conditions and inhibit oxidative phosphorylation in the mitochondriaIt has high localized intestianl concentrations
Who should be responsible for discovering and developing new antibiotics? Support your answer with reasoning.
-those who understand soul microorganisms thoroughly and have access to more than just a standard laboratory methods or culturing antibiotics
When is using a broad-spectrum antimicrobial drug warranted?
A broad-spectrum antimicrobial may be selected to treat an infection when a narrow-spectrum drug fails because of development of drug resistance by the target pathogen. *Broad-spectrum antimicrobials can target gram positive AND negative)
Why does the length of time of antimicrobial treatment for tuberculosis contribute to the rise of resistant strains?
Because tuberculosis is recommended to be treated for 6 months to a year and many people don't actually take their antibiotics for the whole time and that leads to antibiotic resistance The long treatment allows strands to build up resistance over the time period; these resistant strands lead to more and more of the microbe to be resistant.
The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.
Colostridium difficile
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
Efflux pump
Can an Etest be used to find the MBC of a drug? Explain.
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 microbroth dilutions
(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) β-lactamases can degrade vancomycin.
False
How does the biology of HIV necessitate the need to treat HIV infections with multiple drugs?
HIV is a virus with a complex life cycle - It targets positive white blood cells - it's a retrovirus - the reverse transcriptase causes many mutations
Why was Salvarsan considered to be a "magic bullet" for the treatment of syphilis?
Is was called the "magic bullet" because Salversan was the first drug to directly target a specific disease causing agent
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
Kirby-Bauer disk diffusion test
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 antimicrobial sD. short-term use of broad-spectrum antimicrobials
Long term use of broad-spectrum antibiotics
What is the difference between multidrug resistance and cross-resistance?
MDR's: carry one resistance to multiple antimicrobials Cross resistance: a single resistance mechanism with resistance to multiple antomicrobial drugs
What is the difference between MIC and MBC?
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
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
MRSA (methicillin-resistant Staphylococcus aureus)
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 inhibitors
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
Oral (lol)
Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.
Prokaryotic
If human cells and bacterial cells perform transcription, how are the rifamycins specific for bacterial infections?
Rifamycins: functions by blocking RNA polymerase activity in bacteria, and are different from those in Eukaryotes, providing selective toxicity against bacterial cells
Where do antimicrobials come from naturally? Why?
Streptomyces - bacteria found in soil ?
When prescribing antibiotics, what aspects of the patient's health history should the clinician ask about and why?
The patient's age and body mass Their ability to take oral medications Their liver and kidney function, history, or diseases Current drugs or medications for possible interactions
(T/F) The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.
True
The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.
acinomycetes
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
artemisinin
Which of the following drug classes specifically inhibits neuronal transmission in helminths? A. quinolines B. avermectins C. amantadines D. imidazoles
avermectins
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
azidothymidine
Which of the following is not an appropriate target for antifungal drugs? A. ergosterol B. chitin C. cholesterol D. β(1→3) glucan
cholesterol
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
diameter
Which of the following resistance mechanisms describes the function of β-lactamase? A. efflux pump B. target mimicry C. drug inactivation D. target overproduction
drug inactivation
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
efflux pump
The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.
etest
(T/F) Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.
false
Which of the following is not a type of β-lactam antimicrobial? A. penicillins B. glycopeptides C. cephalosporins D. monobactams
glycopeptides
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.
in a localized population
Which of the following antimicrobials inhibits the activity of DNA gyrase? A. polymyxin B B. clindamycin C. nalidixic acid D. rifampin
nalidixic acid
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
selective toxicity
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? - resistant - semisynthetic - synthetic - natural
semisynthetic
Which of the following has yielded compounds with the most antimicrobial activity? A. water B. air C. volcanoes D. soil
soil
Which of the following antimicrobial drugs is synthetic? - sulfanilamide - penicillin - actinomycin - neomycin
sulfanilamide
Which of the following does not bind to the 50S ribosomal subunit? A. tetracyclines B. lincosamides C. macrolides D. chloramphenicol
tetracyclines
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
treatment of strep throat caused by culture identified Streptococcus pyogenes
(T/F) Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.
true
