micro practice exam 4
The minimum sterilizing conditions in a steam autoclave are a) 100°C for 30 minutes. b) 121°C at 15 psi for 15 minutes. c) 71.6°C for 15 seconds. d) 160°C for 2 hours. e) 63°C for 30 minutes.
121°C at 15 psi for 15 minutes.
A drug exhibiting which therapeutic index value would be the safest, most effective to use on a patient? a) 20 b) 10 c) 1 d) 0.1 e) any choice would be equally effective
20
Which of the following is true regarding the use of osmotic pressure as an antimicrobial agent? a) Salt is an effective solute to create an osmotic pressure gradient outside of a cell; however, the use of sugar, such as in jams and jellies, works via a different mechanism. b) Exposing organisms to the air on a benchtop so they completely dry out is an example of using osmotic pressure as a means of microbial control. c) Salts and sugars external to a microbe create a hypotonic environment, which causes lysis of the cell. d) Exposing a microbe to a hypertonic environment draws water out of the cell, causing plasmolysis.
Exposing a microbe to a hypertonic environment draws water out of the cell, causing plasmolysis.
Antiviral drugs that target reverse transcriptase would be used to treat infections caused by ______. a) influenze A virus b) herpes zoster virus c) hepatitis C virus d) HIV E) respiratory syncytial virus
HIV
Your patient has been on antibiotics for 6 weeks after a case of streptococcal endocarditis, an infection of the inner heart wall. The infection clears up. However, the patient just visited you about a urinary tract infection, and the lab verified that the culprit was E. coli. What do you hypothesize happened in this situation? a) Her normal microbiota in the genitourinary tract were killed, allowing E. coli (not killed by the antibiotics) to establish an infection. b) The antibiotics damaged her immune system, making her very susceptible to environmental bacteria. c) The lab has made a mistake in identifying the cause, and, in fact, the UTI was caused by the original Streptococcus. d) The lab has made a mistake in identifying the cause, and, in fact, the endocarditis was caused by the E. coli.
Her normal microbiota in the genitourinary tract were killed, allowing E. coli (not killed by the antibiotics) to establish an infection.
Which of the following methods of microbial control is mismatched? a) Exposure of surgical equipment to ultraviolet light - radiation b) Pickling eggs - osmotic pressure c) Heating a liquid to 71.6oC for 15 seconds - pasteurization d) Autoclaving nutrient agar before pouring into Petri plates - sterilization
Pickling eggs - osmotic pressure
You have given a dosage of an antibiotic to a patient for his infection, but the patient is not getting any better. The MIC tests shows that the drug that you prescribed, at the dosage that was given, should work against this particular strain of bacterium. What do you think might be the problem? a) The drug was improperly made at the pharmaceutical company, so is no longer effective. b) the patient is resistant to the drug c) The drug might be broken down in the patient's body before it can have its full effect on the bacterium. d) The bacterium is immune to the chemical effects of the drug.
The drug might be broken down in the patient's body before it can have its full effect on the bacterium.
After sterilizing the plates, pouring the sterilized agar medium, and then leaving the plates out at room temperature for a day or two to let them solidify and dry, you find contaminating bacterial colonies growing on the agar. Predict what has happened in this situation. a) The agar had bacteria in it, even after sterilization in the autoclave. b) The lids of the Petri dishes were inadvertently left on while being sterilized. c) The room temperature enhanced the growth of normal biota of the agar. d) Air got into the poured agar plates, contaminating them.
The lids of the Petri dishes were inadvertently left on while being sterilized.
Which of the following is an advantage to using phenolics as antimicrobial agents? a) Which of the following is an advantage to using phenolics as antimicrobial agents? b) They are effective sterilants against all microbial forms. c) they have low toxicity d) The presence of organic matter does not limit its antimicrobial qualities.
The presence of organic matter does not limit its antimicrobial qualities.
Which of the following is a disadvantage of dry heat methods such as using a Bunsen burner to incinerate microbes from an inoculating loop and the use of a hot air oven? a) Neither of these methods actually sterilize; they only kill vegetative cells. b) Bunsen burners and hot air ovens only reach a maximum of 100oC so they are not effective against endospores. c) Bunsen burners take too long to sterilize and hot air ovens are hazardous for the operators. d) Use of an open flame can be dangerous and hot air ovens take much longer to sterilize than autoclaves.
Use of an open flame can be dangerous and hot air ovens take much longer to sterilize than autoclaves.
Ampicillin, amoxicillin, mezlocillin, and penicillin G all have ______. A) an expanded spectrum of activity b) a semisynthetic nature c) a beta-lactam ring d) resistance to action of penicillinase
a beta-lactam ring
A superinfection results from a) build up of a drug to toxic levels in the patient b) the wrong drug administered to the patient c) an immune system reaction to the drug d) a decrease in most normal biota resulting in the overgrowth of an unaffected species.
a decrease in most normal biota resulting in the overgrowth of an unaffected species.
Each of the following results in drug resistance, except a) a drug binding site being altered b) a drug being blocked from entering cell c) a drug being used as nutrient by cell d) a drug being inactivated e) a drug being pumped out of the cell
a drug being used as a nutrient by the cell
A clinical microbiologist makes serial dilutions of several antimicrobials in broth, and then incubates each drug dilution series with a standard amount of a patient's isolated pathogen. What is this microbiologist setting up? a) a antibiogram b) an E-test c) a kirby-bauer technique d) therapeutic index (TI) e) a minimum inhibitory concentration (MIC) test
a minimum inhibitory concentration (MIC) test
HEPA filters are used to remove microbes from A. air. B. liquids. C. human tissues. D. medical instruments. E. All of the choices are correct.
air
Endospores can be inactivated by... a) ethylene oxide for 3 or more hours b) glutaraldehyde for 3 or more hours c) incineration d) dry heat at 170C for 2 hours e) all choices are correct
all choices are correct
Hydrogen peroxide is a) sporicidal b) bactericidal c) virucidal d) fungicidal e) all choices are correct
all choices are correct
Important characteristics of antimicrobial drugs include a) low toxicity for human tissues b) high toxicity against microbial cells c) a lack of serious side effects in humans d) stability and solubility in body tissues and fluids e) all choices are correct
all choices are correct
Microbial resistance resulting from mutation occurs because a) bacterial genomes undergo mutation rapidly b) bacterial genomes undergo mutation often c) short generation times accumulate mutations in populations d) mutations are passed b/w organisms e) all choices are correct
all choices are correct
The cellular basis for bacterial resistance to antimicrobials include a) bacterial chromosomal mutations b) synthesis of enzymes that alter drug structure c) prevention of drug entry into cell d) alteration of drug receptors on cell targets e) all choices are correct
all choices are correct
Which of the following items are typically irradiated in order to kill microbes? A) human tissues such as heart valves and skin b) operating room air c) surgical gloves d) cured meats e) all choices are correct
all choices are correct
Alcohols a. are skin degerming agents. b. at 50% or higher concentrations dissolve cell membrane lipids. c. denature proteins when ia a 50-95% alcohol-water solution. d. disinfect items soaked in alcohol. e. all of the choices are correct
all of the choices are correct
Which of the following factors will influence the action of microbial agents? a) # of microorganisms b) mode and dosage of the agent c) temp and pH d) type of microorganisms present e) all of choices will influence the action
all of the choices will influence the action
Which of the following germicides is/are also sporicidal? a) betadine b) chlorine c) phenolics d) chlorhexidine e) all of these except phenolics
all of these except phenolics
Substances that are naturally produced by certain microorganisms that can inhibit or destroy bacteria are called ______. a) semisynthetic drugs b) narrow-spectrum drugs c) broad-spectrum drugs d) synthetic drugs e) antibiotics
antibiotics
sulfonamides... a) damage cell membranes b) block peptidases that cross-link glycan molecules c) are metabolic analogs of PABA and block folic acid synthesis. d) interfere with elongation of peptidoglycan e) attach to 30S ribosomal subunit and disrupt protein synthesis
are metabolic analogs of PABA and block folic acid synthesis.
There are fewer antifungal, antiprotozoan, and antihelminthic drugs compared to antibacterial drugs because fungi, protozoa, and helminths a) are not affected by antimicrobials b) are so similar to human cells that drug selective toxicity is difficult to achieve. c) have fewer target sites in their cells compared to bacteria d) are parasites found inside human cells e) do not cause many human infections
are so similar to human cells that drug selective toxicity is difficult to achieve.
Aminoglycosides a) block peptidases that cross-link glycan molecules. b) attach to the 30S ribosomal subunit and disrupt protein synthesis. c) are metabolic analogs of PABA and block folic acid synthesis. D) destroy peptidoglycan e) damage cell membranes
attach to the 30S ribosomal subunit and disrupt protein synthesis.
What instrument is most effective for pressure-temperature sterilization? a) oven b) bunsen burner c) water-bath d) incubator e) autoclave
autoclave
What antibiotic is mixed with neomycin and polymyxin to make an antibiotic ointment (Neosporin) for superficial skin infections? a) bacitracin b) streptomycin c) chloramphenicol d) clindamycin e) vancomycin
bacitracin
Which of the following microbial forms has the highest resistance to physical and chemical controls? a) fungal spores b) naked viruses c) bacterial endospores d) protozoan cysts e) yeast
bacterial endospores
Placing organisms at 4oC is ______. a) bacteriostatic b) bactericidal c) sterilization d) germicidal e) decontamination
bacteriostatic
Iodophors include ______. a) chlorhexidine b) betadine c) alcohols d) chloramines e) tincture of iodine
betadine
Penicillins and cephalosporins a) block peptidases that cross-link glycan molecules. B) attach to the 30S ribosomal subunit and disrupt protein synthesis. C) damage cell membranes d) destroy peptidoglycan E) are metabolic analogs of PABA and block folic acid synthesis
block peptidases that cross-link glycan molecules.
Which of the following is not a mode of action of antiviral drugs? a) bond to ergosterol in the cell membrane b) block penetration c) block transcription and translation d) inhibit DNA synthesis e) block maturation
bond to ergosterol in the cell membrane
Streptomycin, an aminoglycoside, inhibits protein synthesis a) by preventing the formation of the initiation complex. b) by binding to the tRNA preventing peptide bond formation between amino acids. C) by binding to the ribosome, preventing translocation due to interference with the attachment of mRNA. d) by interfering with both the initiation and elongation stages of translation.
by interfering with both the initiation and elongation stages of translation.
The use of any chemical in the treatment, relief, or prophylaxis of a disease is called ______. a) synergism b) nephrotoxicity c) prophylaxis d) selective toxicity e) chemotherapy
chemotherapy
The drug that is used to treat typhoid fever and brain abscesses, but can cause aplastic anemia, is ______. a) gentamicin b) ciprofloxacin c) chloramphenicol d) bacitracin e) clindamycin
chloramphenicol
The compound that is an organic base containing chlorine and two phenolic rings, and is used increasingly for wound degerming, neonatal washes, hand scrubbing, and prepping surgical skin sites is ______. a) a quaternary ammonium compound b) carbolic acid c) chlorhexidine d) triclosan e) formalin
chlorhexidine
A chemical that inhibits beta-lactamase enzymes is ______. a) clavulanic acid b) imipenem c) aztreonam d) penicillinase e) synercid
clavulanic acid
The drug used against intestinal anaerobic bacteria, that can also alter normal biota leading to antibiotic-associated colitis, is ______. a) bacitracin b) ciprofloxacin c) gentamicin d) chloramphenicol e) clindamycin
clindamyin
Drugs that act by mimicking the normal substrate of an enzyme, thereby blocking its active site, are called ______. a) noncompetitive inhibitors b) blockers c) inhibitors d) competitive inhibitors
competitive inhibitors
Scrubbing or immersing the skin in chemicals to reduce the numbers of microbes on the skin is ______. a) degermation b) sanitization c) disinfection d) sterilization
degermation
Removal of moisture by dehydration is called ______. a) flash freeze b) sterilization c) pasteurization d) lypophilization e) desiccation
desiccation
The sterilizing gas used in chemiclaves is ______. a) iodophor b) chlorine dioxide c) ethylene oxide d) formaldehyde e) glutaraldehyde
ethylene oxide
Antibiotics that disrupt bacterial ribosomes can also affect a) ribosomal RNA b) eukaryotic small ribosomal subunit c) eukaryotic mito ribosomes d) eukaryotic large ribosomal subunit
eukaryotic mito ribosomes
_____ is a control method that removes microorganisms rather than inhibiting or killing them. A) filtration b) disinfection c) boiling d) sterilization e) radiation
filtration
Who is considered to be the father of modern antibiotics? A) fleming b) domagk c) chargaff d) crick e) watson
fleming
Sulfa drugs work on a) folic acid biosynthesis b) nucleic acid biosynthesis c) ribosome biosynthesis d) peptidoglycan biosynthesis
folic acid biosynthesis
The most serious type of mutation is a ______ mutation. a) back b) frameshift c) silent d) point
frameshift
Ketoconazole, fluconazole, clotrimazole, and miconazole are broad-spectrum azoles used to treat _____ infections. a) bacterial b) helminthic c) fungal d) viral e) protozoan
fungal
Which of the following forms of radiation are in order from the most penetrating to the least penetrating? a) gamma, X rays, cathode b) cathode, gamma, x rays c) cathode, x ray, gamma d) x ray, gamma, cathode e) gamma, cathode, x rays
gamma, X rays, cathode
The fields of genomics and proteomics differ in that a) genomics is the study of an organism's chromosomes and proteomics is the study of transcription and translation of proteins. b) genomics refers to the study of an organism's entire genome, whereas proteomics is the study of expressed proteins. c) genomics is the study of an organism's chromosomes and the resulting proteins are studied in the field of proteomics. d) the field of genomics involves the study of DNA replication and the field of proteomics refers to the study of transcription and translation.
genomics refers to the study of an organism's entire genome, whereas proteomics is the study of expressed proteins.
Which antimicrobial does not inhibit cell wall synthesis? a) cephalosporins b) carbapenems c) penicillins d) gentamicin e) vancomycin
gentamicin
Mebendazole, thiabendazole, and ivermectin are drugs used to treat _____ infections. a) fungal b) bacterial c) viral d) helminthic e) protozoan
helminthic
Physical agents for controlling microbial growth include all of the following except ______. a) boiling water b) pasteurization c) hydrogen peroxide e) UV radiation
hydrogen peroxide
Cold temperatures are considered microbistatic, whereas excessive heat is considered microbicidal. This is due to the fact that a) cold temperatures denature enzymes causing irreparable damage to the cell, whereas heat limits the energy of activation available to drive chemical reactions. b) cold temperatures halt binary fission and is therefore considered a sterilant, whereas heat does not kill spores so it is not an effective method of control. C) in cold temperatures, the energy of activation is not sufficient to drive chemical reactions regardless of the presence of enzymes, whereas excessive heat denatures enzymes and/or incinerates the cell causing irreparable damage. d) cold temperatures freeze and therefore kill the cell, whereas excess heat keeps the cell metabolically active but not dividing.
in cold temperatures, the energy of activation is not sufficient to drive chemical reactions regardless of the presence of enzymes, whereas excessive heat denatures enzymes and/or incinerates the cell causing irreparable damage.
Heavy metals work by A. rupturing the cell membrane. B. inactivating proteins. C. binding to DNA. D. dissolving the cell wall. E. mutating DNA.
inactivating proteins
Antimicrobials that are macrolides a) disrupt cell membrane function b) are hepatotoxic c) include tetracyclines d) include azithromycin, clarithromcyin, and erythromycin. e) are very narrow-spectrum drugs
include azithromycin, clarithromcyin, and erythromycin.
All of the following act as surfactants except ______. a) quaternary ammonia b) detergents c) iodine d) alcohols e) soaps
iodine
All of the following are alkylating control agents except ______. a) formaldehyde b) glutaraldehyde C) iodophor d) propylene oxide e) ethylene oxide
iodophor
dry heat.. a) cannot sterilization b) is used in devices called autoclaves c) includes tyndallization d) will sterilize at 121C for 15 min e) is less efficient than moist heat
is less efficient than moist heat
Which of these drugs has the most narrow-spectrum activity? a) erythromycin b) tetracycline c) isoniazid d) cephalosporins e) aminoglycosides
isoniazid
The drug used for several protozoan infections is ______. a) griseofulvin b) nystatin c) sulfa drugs d) amphotericin B e) metronidazole
metronidazole
Each of the following contributes to emerging drug resistance except a) improper use of antibiotics b) addition of antibiotics to common household products c) ingestion of antibiotics with animal feed d) overuse of antibiotics e) multiple drug therapy
multiple drug therapy
Each of the following is a mechanism for drug resistance transfer between microorganisms, except ______. a) conjugation b) transposons c) R-plasmids d) mutation
mutation
Microbial death occurs when there is A) no reproduction b) a decrease in size c) a change in appearance d) no movement e) all choices occur
no reproduction
If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE (stop)? a) deletion b) nonsense c) insertion d) missense e) silent
nonsense
Which antimicrobial method does not sterilize? a) autoclave b) ionizing radiation c) pasteurization e) ethylene oxide gas
pasteurization
If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE THE BAG RAT? a) nonsense b) silent c) deletion d) insertion e) point
point
Each of the following target bacterial ribosomes, except ______. a) erythromycin b) tetracycline c) polymyxins d) gentamycin e) streptomycin
polymyxins
DNA Polymerase III a) joins okazaki fragments b) unzips DNA helix c) proofreads new DNA d) synthesizes the primer e) removes the primer
proofreads new DNA
The use of a drug to prevent imminent infection is called ______. a) lantibiotics b) prophylaxis c) prebiotics d) synergism e) competitive inhibition
prophylaxis
Your aim is to sterilize prosthetic devices like heart valves and artificial joint structures before being used in the patient. Considering where they will be placed and the probable composition of the devices, what would be the best chemical to use? a) quaternary ammonium compounds b) crystal violet dye c) iodine d) bleach
quaternary ammonium compounds
Which of the following is not a drug group used to treat fungal infections? a) macrolide polyene antibiotics b) griseofulvin c) synthetic azoles d) quinolones e) flucytosine
quinolones
Pasteurization a) kills all vegetative forms b) is used to sterilize food products c) reduces number of endospores d) increases food nutrient value e) reduces number of vegetative forms
reduces number of vegetative forms
DNA Polymerase I a) proofreads DNA chain b) seals DNA gaps c) removes primers e) adds bases to new DNA chain
removes primers
The multidrug resistant pumps in many bacterial cell membranes function by a) bacterial chromosomal mutations b) removing the drug from the cell when it enters c) synthesis of enzymes that alter drug structure
removing the drug from the cell when it enters
If pathogen A is more resistant to an erythromycin disc on a Kirby-Bauer plate compared to pathogen B, then pathogen A will have a/n _____ zone of inhibition compared to pathogen B. a) equal b) larger c) smaller
smaller
Sterilization is achieved by a) flash pasteurization b) boiling water c) hot water d) steam autoclave e) all choices are correct
steam autoclave
Which group are the key drugs used to treat Hansen's disease (leprosy)? a) streptomyces b) sulfones c) sulfonamides d) fluoroquinolones e) polymyxins
sulfones
Broad-spectrum drugs that disrupt the body's normal biota often cause ______. a) allergic reactions b) drug toxicity c) superinfections d) nephrotoxicity
superinfections
Selective toxicity refers to damage to a) nucleic acids b) pathogenic organisms c) prokaryotic cell membranes d) target organisms but not vertebrate cells
target organisms but not vertebrate cells
Which of the following is not an aminoglycoside? a) gentamicin b) streptomycin c) tobramycin d) tetracycline e) amikacin
tetracycline
The _____ are drugs that deposit in developing teeth and cause a permanent brown discoloration. a) cephalosporins b) penicillins c) streptomycins d) macrolides e) tetracyclines
tetracyclines
You have taken E. coli strain A which has its own plasmids, and mixed it with E. coli B strain without plasmids. E. coli B cells now have plasmids but, in addition, they also carry some genes from E. coli A strain. What has happened is a) the E. coli B cells have become mutants of the original culture. b) vertical transmission of DNA has occurred. c) an example of transformation d) the cells of E. coli A were Hfr cells.
the cells of E. coli A were Hfr cells.
Looking at your results of the Ames test using bacteriological agar medium plates lacking the amino acid histidine, you find that there are many colonies growing on the agar. How do you interpret this result? a) The bacterium does not have any plasmids, so it cannot grow on the medium. b) the chemical being tested is mutagenic c) The bacterium has turned its operon genes on, producing proteins necessary for growth. d) The drug being tested has no inhibitory effect on the bacterium; therefore, it is not a good antibiotic to give for treatment of disease.
the chemical being tested is mutagenic
A high therapeutic index is advantageous. This refers to a) the ratio between low selective toxicity and high human toxicity. b) selective toxicity and human toxicity are both high. c) high efficacy of the drug against the target microbe. d) the ratio between high selective toxicity and low human toxicity.
the ratio between high selective toxicity and low human toxicity.
A ratio of the dose of the drug that is toxic to humans versus the minimum effective dose for that pathogen is assessed to predict the potential for toxic drug reactions. This is called the ______. a) E-test b) therapeutic index (TI) c) minimum inhibitory concentration (MIC) d) kirby-bauer technique e) antibiogram
therapeutic index (TI)
The lowest temperature needed to kill or inactivate all microbes in 10 minutes is the a) death phase point b) thermal death point (TDP) c) sporicidal time d) thermal death time (TDT)
thermal death point (TDP)
Which of the following is not true of transposons? a) they can replace damaged DNA b) they can transfer drug resistance c) they are always part of plasmids d) they can change pigmentation e) they can change the genome
they are always part of plasmids
An ideal antimicrobial therapeutic drug exhibits all of the following characteristics, except a) they are easily broken down by host b) they are easily administered c) they are nonallergenic d) they have limited capacity to elicit resistance e) they are nontoxic to host
they are easily broken down by host
All of the following pertain to hypochlorites except a) they are found in iodophors b) they release hypochlorous acid in solution c) they are found in common household bleach d) they are used to disinfect dairy, restaurant, and medical equipment e) they cause denaturation of enzymes
they are found in iodophors
When considering time and temperature as factors in microbicidal activity, a) time is not a factor, only temp b) they are directly proportional to each other c) they must be equal value (30 min at 30C) d) they are inversely proportional to each other
they are inversely proportional to each other
All of the following pertain to cephalosporins, except a) they have beta-lactam ring b) newer generations have activity against gram-negative bacteria. c) many are administered by injection, not orally. d) they have greater resistance to beta-lactamases. e) they are synthetic drugs
they are synthetic drugs
Beta-lactams are selectively toxic because a) they inhibit the formation of peptidoglycan, which humans do not make. b) they cause hepato- and nephrotoxicity in humans. c) they initiate allergic reactions in many humans. d) they often initiate the evolution of drug-resistant organisms.
they inhibit the formation of peptidoglycan, which humans do not make.
A mutation has occurred during DNA replication while the cell was preparing to divide. As a result of this, the codon ACU of mRNA has now become ACC. Interestingly, there is no change to the protein being made. Why not? a) this is a silent mutation b) This is not a mutation that causes a big change, so there is no change to the protein being made. c) The original amino acid isoleucine was changed to leucine, but they are the same variation of amino acid so no change to the protein. d) The mutation was fixed, and even though the codon is now ACC the correct amino acid is put into place for the normal protein.
this is a silent mutation
Which of the following is not a heavy metal? a) merthiolate b) zinc c) mercurochrome d) tincture of iodine e) silver nitrate solution
tincture of iodine
Intermittent sterilization, which uses 3 days of lower temperature steam for short periods of time, is also called ______. a) incubation b) tyndallization c) disinfection d) desiccation e) pasteurization
tyndallization
Agents that can denature microbial proteins include all of the following except ______. a) metallic ions b) alcohol c) x rays d) moist heat e) acids
x rays
