Exam #5 practice questions
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
When is using a broad-spectrum antimicrobial drug warranted?
Broad-spectrum antimicrobial drugs can be warranted for serious systemic infections when there is no time to determine the causative agent. These drugs are used to treat the patient with this infection when awaiting lab results to determine the infectious pathogen.Narrow-spectrum drugs are used when a specific pathogen has been identified. Using this narrow spectrum drug will only target this one pathogen, and will not harm other microbials.
The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.
Clostridium difficile
How does the biology of HIV necessitate the need to treat HIV infections with multiple drugs?
Due to the fact that HIV remains dormant in cells even after HIV concentrations in the blood have disappeared, patients are forced to undergo drug therapy for life. Multiple drugs then need to be used in order to combat drug resistance.
The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.
Etest
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 microbrorh dilutions
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
Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.
False
β-lactamases can degrade vancomycin.
False
Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe? Etest microbroth dilution test Kirby-Bauer disk diffusion test macrobroth dilution test
Kirby-Bauer disk diffusion test
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? MRSA VRE CRE ESBL-producing bacteria
MRSA
Where do antimicrobials come from naturally? Why?
Many soil bacteria and archaea naturally produce many commonly employed antibiotics. Their ability to produce antibiotics gives them an advantage because it kills of their competition when competing for limited resources in their environment
What is the difference between multidrug resistance and cross-resistance?
Multi-drug: carry one or more resistance mechanisms, making them resistant to multiple antimicrobials Cross-resistance: a single resistance mechanism confers resistance to multiple antimicrobial drugs
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?
Niclosamide inhibits ATP formation under anaerobic conditions and inhibit oxidative phosphorylation in the mitochondriaI has high localized intestianl concentrations
If human cells and bacterial cells perform transcription, how are the rifamycins specific for bacterial infections?
Rifamycins are specific for bacterial infections because these drugs block transcription by binding to bacterial RNA polymerase, not eukaryotic RNA polymerase. Drugs can also target and disrupt the peptidoglycan membranes of bacterial cells, which human cells lack.
Why are yeast infections a common type of superinfection that results from long-term use of broad-spectrum antimicrobials?
Superinfection: a secondary infection in a patient having a preexisting infection This is when broad-spectrum antimicrobials kill protective microbiota that allow another pathogen to cause a secondary infection
When prescribing antibiotics, what aspects of the patient's health history should the clinician ask about and why?
The clinician should know if the patient suffers from certain diseases. If the patient has taken other drugs in the past or is currently taking them, it is important to know what they are to examine any possible interactions that may occur. Also, the clinician should know if the patient suffers from liver or kidney dysfunctions. If the clinician doesn't know this, then they may prescribe a drug that the patient's body may not be able to fully metabolize, resulting in higher levels of toxicity and therefore more side effects.
In nature, why do antimicrobial-producing microbes commonly also have antimicrobial resistance genes?
The might have resistance genes from mutation or through horizontal gene transfer
In considering the cell structure of prokaryotes compared with that of eukaryotes, propose one possible reason for side effects in humans due to treatment of bacterial infections with protein synthesis inhibitors.
The ribosomes in prokaryotes differ from eukaryotes. Side effects can be phototoxicity and liver toxicity. This could be because certain proteins are blocked from being made or they altered and unable to do their normal job.
How is the information from a Kirby-Bauer disk diffusion test used for the recommendation of the clinical use of an antimicrobial drug?
The test doesn't necessarily show efficacy, but it shows which antibacterials a bacterial pathogen is susceptible to or resistant to
Why can't drugs used to treat influenza, like amantadines and neuraminidase inhibitors, be used to treat a wider variety of viral infections?
They can't be used because they aren't fully understood, but it is known that they target the protein that is involved in the escape of the influenza virus
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?
They stop when their symptoms dissipate and they are unaware of the negative consequences Fails to kill the target organisms to expected levels and selects for drug-resistant variants within the target population
Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.
True
The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.
True
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.
You can use polymyxins (a natural peptide antibiotic) to target the cell wall. They are lipophilic with detergent-like properties and interact with the lipopolysaccharide component of the outer membrane of gram-negative bacteria.
The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.
actinomycetes
Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells? artemisinin amphotericin b praziquantel pleconaril
artemisinin
Which of the following drug classes specifically inhibits neuronal transmission in helminths? quinolines avermectins amantadines imidazoles
avermectins
Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV? acyclovir ribavirin adenine-arabinoside azidothymidine
azidothymidine
Which of the following is not an appropriate target for antifungal drugs? ergosterol chitin cholesterol β(1→3) glucan
cholesterol
In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation. diameter microbial population circumference depth
diameter
Which of the following resistance mechanisms describes the function of β-lactamase? efflux pump target mimicry drug inactivation target overproduction
drug inactivation
Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes? efflux pump target mimicry target modification target overproduction
efflux pump
Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials? drug modification target mimicry target modification efflux pump
efflux pump
Which of the following is not a type of β-lactam antimicrobial? penicillins glycopeptides cephalosporins monobactams
glycopeptides
The utility of an antibiogram is that it shows antimicrobial susceptibility trends over a large geographic area. for an individual patient. in research laboratory strains. in a localized population.
in a localized population.
Why was Salvarsan considered to be a "magic bullet" for the treatment of syphilis?
it did kill the syphilis-causing bacteria without poisoning the patient
Which of the following combinations would most likely contribute to the development of a superinfection? long-term use of narrow-spectrum antimicrobials long-term use of broad-spectrum antimicrobials short-term use of narrow-spectrum antimicrobials short-term use of broad-spectrum antimicrobials
long-term use of broad-spectrum antimicrobials
Which of the following antimicrobials inhibits the activity of DNA gyrase? polymyxin B clindamycin nalidixic acid rifampin
nalidixic acid
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? oral intravenous topical parenteral
oral
Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.
prokaryotic
Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host? mode of action therapeutic level spectrum of activity 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? water air volcanoes 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? tetracyclines lincosamides macrolides chloramphenicol
tetracyclines
Who should be responsible for discovering and developing new antibiotics? Support your answer with reasoning.
those who understand soul microorganisms throughly and have access to more than just a standard laboratory methods or culturing antibiotics
Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug? treatment of a polymicrobic mixed infection in the intestine prophylaxis against infection after a surgical procedure treatment of strep throat caused by culture identified Streptococcus pyogenes empiric therapy of pneumonia while waiting for culture results
treatment of strep throat caused by culture identified Streptococcus pyogenes
