Lecture 8 Flashcards
Process by which ALL living cells, spores, and viruses are destroyed on an object.
Sterilization
The killing or removal of DISEASE-PRODUCING organisms from inanimate surfaces; it does not necessarily result in sterilization.
Disinfection
Similar to disinfection but applies to removing pathogens from the surface of LIVING tissues, such as skin.
Antiseptics
Consists of reducing the microbial population to safe levels and usually involves cleaning an object as well as disinfection.
Sanitation
___ agents kill microbes.
Cidal
____ agents inhibit or control growth.
Static
Explain how microbe population size influences sterilizing agent damage.
The larger the population, the longer it takes to decrease it.
Explain how microbe population composition influences sterilizing agent damage.
Spores are much more difficult to kill. Spores require 10% bleach, whereas other microbes only require 1%.
____ disrupt the plasma membrane by denaturing proteins and disrupting plasma membrane.
Phenols
Alcohols are not effective against ?
Fungal spores and bacterial endospores
Pure alcohol is not as effective as 70% because ?
Denaturation of proteins requires water
Because alcohols evaporate quickly…
they may not contact the microorganism long enough to be effective.
5 physical agents to control growth:
- Heat
- Pressure
- Cold
- Filtration
- Irradiation
The ____ ____ is based on the highest dilution (lowest concentration) that will kill all bacteria after 10 minutes of exposure.
phenol coefficient
The ____ is defined as the lowest concentration of the drug that will prevent the growth of an organism
Minimum Inhibitory Concentration (MIC)
The ____ ____ test is used to determine the minimum inhibitory concentration and the minimum bactericidal concentration (MBC) of a chemotheraputic agent.
Broth-dilution
The lowest concentration of a chemotheraputic drug needed to kill a pathogen.
Minimum bactericidal concentration (MBC)
Neither ____ or ____ can distinguish whether a drug is bactericidal.
MIC; Kirby-Bauer test
The disk diffusion method is also known as the ?
Kirby-Bauer test
A ____ in a petri dish is an area where the pathogen does not grow because the chemotheraputic drug inhibited it.
Zone of inhibition
The ____ test is an advanced diffusion method that determines the lowest concentration of chemotheraputic agent that inhibits visible growth of bacteria.
Minimum inhibitory concentration (MIC)
The ____ uses a series of round filter paper disks impregnated with different antibiotics.
Kirby-Bauer assay
For an antibiotic to stop bacterial growth in the patient, the drug’s concentration in tissue must remain higher than the ____ at all times.
MIC
Antibiotics exhibit selective toxicity because they disturb ____ or ____ unique to the target cell.
enzymes; structures
Misuse of antibiotics selects for ____ mutants.
resistance
Antibitoic misuse includes:
- Using outdated or weakened antibiotics
- Using antibiotics for the common cold and other inappropriate conditions
- Using antibiotics in animal feed
- Failing to complete the prescribed regimen
- Using someone else’s leftover prescription
Four ways a microbe can become resistant to an antibiotic:
- Modify the target so that it no longer binds to antibiotic
- Destroy antibiotic before it gets into cell
- Add modifying functional groups that inactivate antibiotic
- Pump antibiotic out using transport proteins
An altered DNA gyrase no longer binding to a quinolone is an example of ?
Modifying the target
The enzyme beta-lactamase (penicillinase) is an example of ?
a microbe destroying an antibiotic
Enzymes that modify and inactivate aminoglycosides is an example of ?
Adding modifying groups
Tetracycline resistantance due to an efflux pump is an example of ?
Pumping an antibiotic out
Beta-lactamase breaks a bond in the ____ ring of penicillin to disable the molecule.
Beta-lactam
Rapid, large scale changes of genetic elements are usually mediated by ____, such as viruses and transposons.
horizontal gene transfer
In addition to small, spontaneous mutations, microbes can gain and lose entire genes and undergo rearrangements and duplications. This is known as ?
horizontal gene transfer
Importing free DNA from the environment into bacterial cells is known as ?
Transformation
Mechanism by which cells in a biofilm coordinate their activities in response to environmental stimuli is called ?
Quorum sensing
____ enables microorganisms to detect their cell density through the release and binding of small, diffusible molecules called “autoinducers”
Quorum sensing
____ requires intimate cell contact typically initiated by a sex pilus that protrudes from the donor cell.
Conjugation
In ____, DNA is directly transferred from one prokaryote to another by means of a pilus which brings the organisms in contact with each other.
conjugation
The genes encoding the ability to conjugate are located on a bacterial plasmid called the ?
F plasmid
The F plasmid is also known as the ?
fertility factor
The conjugation pilus is also known as the ?
F pilus
Transfer of DNA through direct contact using a pilus is called ?
Conjugation
Mechanism of horizontal gene transfer in bacteria in which genes are transferred through viral infection is called ?
Transduction
Mechanism of horizontal gene transfer in which naked environmental DNA is taken up by a bacterial cell is called ?
Transformation
In ____ transduction, any piece of chromosomal DNA may be transferred to a new host cell by accidental packaging of chromosomal DNA into a phage head during assembly.
Generalized
____ transduction results from the imprecise excision of a lysogenic prophage from the bacterial chromosome.
Specialized
Viruses that infect bacteria (bacteriophages) may also move short pieces of chromosomal DNA from one bacterium to another in a process called ?
Transduction
The process by which a phage carries a payload of host DNA from one cell to another is called ?
transduction
In ____ transduction only host DNA is packaged.
generalized
In ____ transduction a prophage (integrated phage) leaves the host and takes some of the host DNA. The new host is lysogenically converted.
specialized
When microbial growth medium is made, it is put into the autoclave to ____, the medium before organisms can be inoculated and grown into a pure culture.
sterilize
Selective toxicity for antiviral drugs is ______ to achieve as compared to selective toxicity for antibacterial drugs.
A. easier
B. harder
C. equally different
B. harder
Tetracycline is an antibiotic that inhibits bacterial protein synthesis without killing the bacterial cell. This antibiotic can be classified as ________.
A. virustatic
B. fungicidal
C. bacteriocidal
D. bacteriostatic
D. bacteriostatic
After three minutes of exposure to an antibacterial agent, only 100 cells are living from the 1000 cells at the start. How many cells will still be living after nine minutes of exposure?
A. 1,000
B. 10
C. 1
D. 100
C. 1
Which of the following allows for long-term storage of microbial cells?
A. lyophilization
B. sterilization
C. refrigeration
D. pasteurization
A. lyophilization
How can drugs that are sensitive to heat and chemical sterilization be sterilized so they can be safely administered to sick individuals?
A. filtration through microscope filters
B. using a laminar flow biological safety cabinet
C. refrigeration
D. lyophilization
A. filtration through microscope filters
Which of the following is NOT a factor that affects the efficacy of a disinfectant?
A. the kinds of organisms present
B. the presence of inorganic matter
C. surface tension
D. corrosiveness
B. the presence of inorganic matter
Which of the following is a more accurate method for determining the ability of a disinfectant to kill microorganisms on a particular surface?
A. gas sterilization test
B. use-dilution test
C. phenol coefficient test
D. antimicrobial touch test
B. use-dilution test
Antibiotics with a high degree of ________________ are less likely to harm the host.
A. minimum inhibitory concentration
B. selective toxicity
C. zone of inhibition
D. spectrum toxicity
B. selective toxicity
Penicillin primarily kills Gram-positive bacteria. It can be classified as
A. amphiphatic
B. narrow spectrum
C. low molecular weight
D. broad spectrum
B. narrow spectrum
Which of the following is measured by the minimum inhibitory concentration of an antibiotic?
A. how little of an antibiotic is needed to stop growth of an organism
B. how many different organisms the antibiotic inhibits
C. how little of an antibiotic is needed to kill an organism
D. maximum dose the patient tolerates
A. how little of an antibiotic is needed to stop growth of an organism
What is the desired ratio between the therapeutic dose and the toxic dose for an antibiotic?
A. The therapeutic dose should be much lower than the toxic dose.
B. The therapeutic and toxic doses should be equal.
C. The therapeutic dose should be higher than the toxic dose.
D. The relationship between those doeses does not matter.
A. The therapeutic dose should be much lower than the toxic dose.
Drugs that target RNA polymerase are inhibitors of ________.
A. reverse transcription
B. translation
C. transcription
D. DNA replication
C. transcription
Which of the following is NOT a mechanism of antibiotic resistance?
A. addition of modifying groups to activate the antibiotic
B. pumping of the antibiotic out of the cell using nonspecific transport proteins
C. modification of target so that it no longer binds the antibiotic
D. destruction of the antibiotic before it gets into the cell
A. addition of modifying groups to activate the antibiotic
Which of the following is NOT an origin of antibiotic resistance genes?
A. spontaneous mutation
B. gene in the chromosome of the antibiotic-producing organism
C. gene duplication followed by random mutation
D. conjugation
D. conjugation
Which of the following is an accurate definition of disinfection?
A. The killing or removal of disease-producing organisms from inanimate surfaces.
B. The removal of pathogens from the surface of living tissues.
C. The reduction of microbial populations to safe levels.
D. The process by which all living cells, spores, and viruses are destroyed on an object.
E. All of the above.
A. The killing or removal of disease-producing organisms from inanimate surfaces.
Factors influencing the speed of lethal damage
- The initial population size.
- Population composition
- Agent concentration or dose for radiation
- Duration of exposure
- Presence of organic material (blood, feces) that can inhibit disinfectant action; organic load.
Name examples of physical control agents.
high or low temperature, desiccation, osmotic pressure, radiation, and filtration.
Four ways that microbes can become resistant to antibiotics.
- Modify The Target so that it no longer binds to the antibiotic.
- Destroy The Antibiotic before it gets into the cell.
- ADD Modifying Groups that inactivate the antibiotic
- Pump The Antibiotic Out of the cell using specific or nonspecific transport proteins.
A germicide is applied to a surface. By definition, this chemical will most likely_______ that surface.
Disinfect
Microbial growth slows down when the sample is ______, but there is no microbial growth at all when the sample is _____.
Refrigerated; Lyophilized
Environments free of microorganisms are known as ______ environments.
A. antiseptic
B. hygienic
C. vaccinated
D. aseptic
D. aseptic
Which of the following is measured by the minimum inhibitory concentration of an antibiotic?
A. how little of an antibiotic is needed to kill an organism.
B. maximum dose the patient tolerates
C. how little of an antibiotic is needed to stop growth of an organism
D. how many different organisms the antibiotic inhibits
C. how little of an antibiotic is needed to stop growth of an organism
Which of the following modes of action would be most selectively toxic?
a. interrupting ribosomal function
b. dissolving the cell membrane
c. preventing cell wall synthesis
d. inhibiting DNA replication
c. preventing cell wall synthesis
____ is commonly used to remove bacteria from heat sensitive solutions.
Membrane filtration
The ____ method is used to test the
effectiveness of a chemical disinfectant against
a particular microbe.
disk-diffusion
The ____ test determines the effectiveness of a disinfectant on a surface.
use-dilution
Which of the following is suitable for use on
tissues for microbial control to prevent infection?
A. disinfectant
B. antiseptic
C. sterilant
D. water
B. antiseptic
Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast?
A. bacteriostatic
B. fungicidal
C. bactericidal
D. fungistatic
D. fungistatic
Which 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 radiation
A. filtration
Bleach is an example of which group of
chemicals used for disinfection?
A. heavy metals
B. halogens
C. quats
D. bisbiguanides
B. halogens
Which 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 test
C. in-use 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 antimicrobials D. short-term use of broad-spectrum antimicrobials
B. long-term use of broad-spectrum
antimicrobials
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
D. selective toxicity
Which of the following resistance mechanisms
describes the function of β-lactamase?
A. efflux pump
B. target mimicry
C. drug inactivation
D. target overproduction
C. 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
A. 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
D. efflux pump
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
C. Kirby-Bauer disk diffusion test
