AO Nursing Micro. Exam 3

Which of the following methods would be used to measure the concentration of bacterial contamination in processed peanut butter?

a. turbidity measurement
b. total plate count
c. dry weight measurement
d. direct counting of bacteria on a calibrated slide under the microscope

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b. total plate count

In which phase would you expect to observe the most endospores in a Bacillus cell culture?

a. death phase
b. lag phase
c. log phase
d. log, lag, and death phases would all have roughly the same number of endospores.

a. death phase

During which phase would penicillin, an antibiotic that inhibits cell-wall synthesis, be most effective?

a. death phase
b. lag phase
c. log phase
d. stationary phase

c. log phase

Which of the following is the best definition of generation time in a bacterium?

a. the length of time it takes to reach the log phase
b. the length of time it takes for a population of cells to double
c. the time it takes to reach stationary phase
d. the length of time of the exponential phase

b. the length of time it takes for a population of cells to double

What is the function of the Z ring in binary fission?

a. It controls the replication of DNA.
b. It forms a contractile ring at the septum.
c. It separates the newly synthesized DNA molecules.
d. It mediates the addition of new peptidoglycan subunits.

b. it forms a contractile ring at the septum

If a culture starts with 50 cells, how many cells will be present after five generations with no cell death?

a. 200
b. 400
c. 1600
d. 3200

c. 1600

Filamentous cyanobacteria often divide by which of the following?

a. budding
b. mitosis
c. fragmentation
d. formation of endospores

c. fragmentation

Which is a reason for antimicrobial resistance being higher in a biofilm than in free-floating bacterial cells?

a. The EPS allows faster diffusion of chemicals in the biofilm.
b. Cells are more metabolically active at the base of a biofilm.
c. Cells are metabolically inactive at the base of a biofilm.
d. The structure of a biofilm favors the survival of antibiotic resistant cells.

c. cells are metabolically active at the base of a biofilm

Quorum sensing is used by bacterial cells to determine which of the following?

a. the size of the population
b. the availability of nutrients
c. the speed of water flow
d. the density of the population

d. the density of the population

Which of the following statements about autoinducers is incorrect?

a. They bind directly to DNA to activate transcription.
b. They can activate the cell that secreted them.
c. N-acylated homoserine lactones are autoinducers in gram-negative cells.
d. Autoinducers may stimulate the production of virulence factors.

a. they bind directly to DNA to activate transcription

An inoculated thioglycolate medium culture tube shows dense growth at the surface and turbidity throughout the rest of the tube. What is your conclusion? a. The organisms die in the presence of oxygen b. The organisms are facultative anaerobes. c. The organisms should be grown in an anaerobic chamber. d. The organisms are obligate aerobes.b. the organisms are facultative anaerobesAn inoculated thioglycolate medium culture tube is clear throughout the tube except for dense growth at the bottom of the tube. What is your conclusion? a. The organisms are obligate anaerobes. b. The organisms are facultative anaerobes. c. The organisms are aerotolerant. d. The organisms are obligate aerobes.a. the organisms are obligate anaerobesPseudomonas aeruginosa is a common pathogen that infects the airways of patients with cystic fibrosis. It does not grow in the absence of oxygen. The bacterium is probably which of the following? a. an aerotolerant anaerobe b. an obligate aerobe c. an obligate anaerobe d. a facultative anaerobeb. an obligate anaerobeStreptococcus mutans is a major cause of cavities. It resides in the gum pockets, does not have catalase activity, and can be grown outside of an anaerobic chamber. The bacterium is probably which of the following? a. a facultative anaerobe b. an obligate aerobe c. an obligate anaerobe d. an aerotolerant anaerobed. an aerotolerant anaerobeWhy do the instructions for the growth of Neisseria gonorrhoeae recommend a CO2-enriched atmosphere? a. It uses CO2 as a final electron acceptor in respiration. b. It is an obligate anaerobe. c. It is a capnophile. d. It fixes CO2 through photosynthesis.c. it is a capnophileBacteria that grow in mine drainage at pH 1-2 are probably which of the following? a. alkaliphiles b. acidophiles c. neutrophiles d. obligate anaerobesb. acidophilesBacteria isolated from Lake Natron, where the water pH is close to 10, are which of the following? a. alkaliphiles b. facultative anaerobes c. neutrophiles d. obligate anaerobesa. alkaliphilesIn which environment are you most likely to encounter an acidophile? a. human blood at pH 7.2 b. a hot vent at pH 1.5 c. human intestine at pH 8.5 d. milk at pH 6.5b. a hot vent at pH 1.5A soup container was forgotten in the refrigerator and shows contamination. The contaminants are probably which of the following? a. thermophiles b. acidophiles c. mesophiles d. psychrotrophsd. psychotrophsBacteria isolated from a hot tub at 39 °C are probably which of the following? a. thermophiles b. psychrotrophs c. mesophiles d. hyperthermophilesc. mesophilesIn which environment are you most likely to encounter a hyperthermophile? a. hot tub b. warm ocean water in Florida c. hydrothermal vent at the bottom of the ocean d. human bodyc. hydrothermal vent at the bottom of the oceanWhich of the following environments would harbor psychrophiles? a. mountain lake with a water temperature of 12 °C b. contaminated plates left in a 35 °C incubator c. yogurt cultured at room temperature d. salt pond in the desert with a daytime temperature of 34 °Ca. mountain lake with a water temperature of 12ºCWhich of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage? a. low pH b. toxic alkaline chemicals c. naturally occurring antibiotics d. low water activityd. low water activityBacteria living in salt marshes are most likely which of the following? a. acidophiles b. barophiles c. halotolerant d. thermophilesc. halotolerantEMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, eosin and methylene blue, inhibit the growth of gram-positive bacteria and distinguish between lactose fermenting and nonlactose fermenting organisms. Lactose fermenters form metallic green or deep purple colonies, whereas the nonlactose fermenters form completely colorless colonies. EMB agar is an example of which of the following? a. a selective medium only b. a differential medium only c. a selective medium and a chemically defined medium d. a selective medium, a differential medium, and a complex mediumd. a selective medium, differential medium, and a complex mediumHaemophilus influenzae must be grown on chocolate agar, which is blood agar treated with heat to release growth factors in the medium. H. influenzae is described as ________. a. an acidophile b. a thermophile c. an obligate anaerobe d. fastidiousd. fastidiousThe number of dying cells is higher than the number of cells dividing a. lag phase b. log phase c. stationary phase d. death phased. death phaseNumber of new cells is equal to the number of dying cells a. lag phase b. log phase c. stationary phase d. death phasec. stationary phaseNew enzymes to use available nutrients are induced a. lag phase b. log phase c. stationary phase d. death phasea. lag phaseBinary fission is occurring at maximum rate a. lag phase b. log phase c. stationary phase d. death phaseb. log phasematch the bacterium with its environment: psychotroph a. food spoiling in fridge b. hydrothermal vent c. deep ocean waters d. human pathogen e. garden composta. food spoiling in fridgematch the bacterium with its environment: mesophile a. food spoiling in fridge b. hydrothermal vent c. deep ocean waters d. human pathogen e. garden compostd. human pathogenmatch the bacterium with its environment: thermophile a. food spoiling in fridge b. hydrothermal vent c. deep ocean waters d. human pathogen e. garden composte. garden compostmatch the bacterium with its environment: hyperthermophile a. food spoiling in fridge b. hydrothermal vent c. deep ocean waters d. human pathogen e. garden compostb. hydrothermal ventmatch the bacterium with its environment: psychrophile a. food spoiling in fridge b. hydrothermal vent c. deep ocean waters d. human pathogen e. garden compostc. deep ocean watersDirect count of total cells can be performed using a ________ or a ________.hemocytometer or a Petroff-Hausser counting chamberThe ________ method allows direct count of total cells growing on solid medium.plate countA statistical estimate of the number of live cells in a liquid is usually done by ________.most probable numberFor this indirect method of estimating the growth of a culture, you measure ________ using a spectrophotometer.turbidityActive growth of a culture may be estimated indirectly by measuring the following products of cell metabolism: ________ or ________.ATP or acid from fermentationA bacterium that thrives in a soda lake where the average pH is 10.5 can be classified as a(n) ________.alkaliphileLactobacillus acidophilus grows best at pH 4.5. It is considered a(n) ________.acidophileA bacterium that thrives in the Great Salt Lake but not in fresh water is probably a ________.halophileBacteria isolated from the bottom of the ocean need high atmospheric pressures to survive. They are ________.barophilesStaphylococcus aureus can be grown on multipurpose growth medium or on mannitol salt agar that contains 7.5% NaCl. The bacterium is ________.halotolerantBlood agar contains many unspecified nutrients, supports the growth of a large number of bacteria, and allows differentiation of bacteria according to hemolysis (breakdown of blood). The medium is ________ and ________.complex and differentialRogosa agar contains yeast extract. The pH is adjusted to 5.2 and discourages the growth of many microorganisms; however, all the colonies look similar. The medium is ________ and ________.complex and selectiveWhich of the following types of medical items requires sterilization? a. needles b. bed linens c. respiratory masks d. blood pressure cuffsa. needlesWhich of the following is suitable for use on tissues for microbial control to prevent infection? a. disinfectant b. antiseptic c. sterilant d. waterb. antisepticWhich biosafety level is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous? a. BSL-1 b. BSL-2 c. BSL-3 d. BSL-4b. BSL-2Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast? a. bacteriostatic b. fungicidal c. bactericidal d. fungistaticd. fungistaticThe decimal reduction time refers to the amount of time it takes to which of the following? a. reduce a microbial population by 10% b. reduce a microbial population by 0.1% c. reduce a microbial population by 90% d. completely eliminate a microbial populationc. reduce a microbial population by 90%Which of the following methods brings about cell lysis due to cavitation induced by rapid localized pressure changes? a. microwaving b. gamma irradiation c. ultraviolet radiation d. sonicationd. sonicationWhich of the following terms is used to describe the time required to kill all of the microbes within a sample at a given temperature? a. D-value b. thermal death point c. thermal death time d. decimal reduction timec. thermal death timeWhich of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples? a. filtration b. desiccation c. lyophilization d. nonionizing radiationa. filtrationWhich of the following refers to a disinfecting chemical dissolved in alcohol? a. iodophor b. tincture c. phenolic d. peroxygenb. tinctureWhich of the following peroxygens is widely used as a household disinfectant, is inexpensive, and breaks down into water and oxygen gas? a. hydrogen peroxide b. peracetic acid c. benzoyl peroxide d. ozonea. hydrogen peroxideWhich of the following chemical food preservatives is used in the wine industry but may cause asthmatic reactions in some individuals? a. nitrites b. sulfites c. propionic acid d. benzoic acidb. sulfitesBleach is an example of which group of chemicals used for disinfection? a. heavy metals b. halogens c. quats d. bisbiguanidesb. halogensWhich chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic? a. sorbic acid b. triclosan c. formaldehyde d. hexaclorophenec. formaldehydeWhich type of test is used to determine whether disinfectant solutions actively used in a clinical setting are being used correctly? a. disk-diffusion assay b. phenol coefficient test c. in-use test d. use-dilution testc. in-use testThe effectiveness of chemical disinfectants has historically been compared to that of which of the following? a. phenol b. ethyl alcohol c. bleach d. formaldehydea. phenolWhich of the following refers to a germicide that can kill vegetative cells and certain enveloped viruses but not endospores? a. high-level germicide b. intermediate-level germicide c. low-level germicide d. sterilantc. low-level germicideT/F: Sanitization leaves an object free of microbes.FalseT/F: Ionizing radiation can penetrate surfaces, but nonionizing radiation cannot.TrueT/F: Moist-heat sterilization protocols require the use of higher temperatures for longer periods of time than do dry-heat sterilization protocols do.FalseT/F: Soaps are classified as disinfectants.FalseT/F: Mercury-based compounds have fallen out of favor for use as preservatives and antiseptics.TrueA medical item that comes into contact with intact skin and does not penetrate sterile tissues or come into contact with mucous membranes is called a(n) ________ item.noncriticalThe goal of ________ ________ protocols is to rid canned produce of Clostridium botulinum endospores.commercial sterilizationIn an autoclave, the application of pressure to ________ is increased to allow the steam to achieve temperatures above the boiling point of water.steamDoorknobs and other surfaces in clinical settings are often coated with ________, ________, or ________ to prevent the transmission of microbes.copper, nickel, or zincIf a chemical disinfectant is more effective than phenol, then its phenol coefficient would be ________ than 1.0.greaterIf used for extended periods of time, ________ germicides may lead to sterility.high-level. In the disk-diffusion assay, a large zone of inhibition around a disk to which a chemical disinfectant has been applied indicates ________ of the test microbe to the chemical disinfectant.susceptibilityA 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. naturalb. semisyntheticWhich of the following antimicrobial drugs is synthetic? a. sulfanilamide b. penicillin c. actinomycin d. neomycina. sulfanilamideWhich 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 antimicrobialsb. long-term use of broad-spectrum antimicrobialsWhich 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. parenterala. oralWhich 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 resultsc. treatment of strep throat caused by culture identified Streptococcus pyogenesWhich 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 toxicityd. selective toxicityWhich of the following is not a type of β-lactam antimicrobial? a. penicillins b. glycopeptides c. cephalosporins d. monobactamsb. glycopeptidesWhich of the following does not bind to the 50S ribosomal subunit? a. tetracyclines b. lincosamides c. macrolides d. chloramphenicola. tetracyclinesWhich of the following antimicrobials inhibits the activity of DNA gyrase? a. polymyxin B b. clindamycin c. nalidixic acid d. rifampinc. nalidixic acidWhich of the following is not an appropriate target for antifungal drugs? a. ergosterol b. chitin c. cholesterol d. β(1→3) glucanc. cholesterolWhich of the following drug classes specifically inhibits neuronal transmission in helminths? a. quinolines b. avermectins c. amantadines d. imidazolesb. avermectinsWhich 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. azidothymidined. azidothymidineWhich 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. pleconarila. artemisininWhich of the following resistance mechanisms describes the function of β-lactamase? a. efflux pump b. target mimicry c. drug inactivation d. target overproductionc. drug inactivationWhich 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 overproductiona. efflux pumpWhich 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 pumpd. efflux pumpWhich 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 bacteriaa. MRSAIn 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. deptha. diameterWhich 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 testc. Kirby-Bauer disk diffusion testThe 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. in a localized populationWhich of the following has yielded compounds with the most antimicrobial activity? a. water b. air c. volcanoes d. soild. soilT/F: Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.falseT/F: β-lactamases can degrade vancomycin.falseT/F: Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.TrueT/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.falseT/F: The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.TrueThe group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.actinomycetesThe bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.Clostridium difficileSelective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.prokaryoticAntiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by preventing viral escape from host cells are called ________.neuraminidase inhibitorsStaphylococcus aureus, including MRSA strains, may commonly be carried as a normal member of the ________ microbiota in some people.nasalThe method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.Etest