Microbiology 2420: Chapter 13 Test
Questions Solved Correct.
What does sepsis refer to? - Answer Microbial contamination-especially in the body.
What is aseptic technique? - Answer How to avoid microbial contamination-flaming, wiping
down surfaces, etc.
What is sterilization? - Answer Absence of all life
What is the difference in antiseptics and disinfectants? - Answer Antiseptics kill bacteria on
animal tissues.
Disinfectants kill bacteria on fomites.
What is the difference in bacteriostatic and bactericidal? - Answer Bacteriostatic stops
bacterial growth.
Bactericidal kills bacteria
What temperature, pressure, and how long do you have to use an autoclave to kill bacteria? -
Answer 121°
15 psi
15 min or more
When using an autoclave what must you do for solids? - Answer Use fast exhaust after 15
min
When using an autoclave what must you do for liquids? - Answer -Use slow exhaust up to
30-60 min
-Fill bottles no more than half way full
-Leave an inch between bottles
What type of growth can survive autoclave and how long can they survive? - Answer Prions
such as mad cow disease can survive 3 hrs of autoclaving, need high pH too while autoclaving to
kill them
, What is an alternative to autoclaving? - Answer Using dry heat on glass at 170° for more
than 2 hours
What do they use in hospitals to kill bacteria and how does it kill bacteria? - Answer Ethylene
oxide gas-alkylates microbial DNA to kill microbes
How is UV light use to kill microbes? - Answer UV at 254-260 nm is used for greater than 20
min forming thymine dimmers in DNA to stop replication and kill bacteria
What does HEPA stand for? - Answer High efficiency Particulate Air Filter
How do HEPA filters work? - Answer They have 0.3 µm pores and for liquids 0.22 to 0.45 µm
- these work because bacteria are 1-2 µm and cannot get through pores, but viruses and some
rickettsia or mycoplasmas can get through the pores
What did Peyton Rous do? - Answer He was the first to describe viruses as filterable agents
that cause plaques in mammalian cell cultures
What is one way to kill virtually ALL microbes? - Answer Ionizing Gamma and X-Rays
What does MIC stand for? - Answer Minimum Inhibitory Concentration-the lowest
concentration of a chemical which prevents visible growth of a bacterium
Describe the Kirby-Bauer or Disk diffusion tests - Answer The Kirby-Bauer assay uses a series
of round filter paper disks impregnated with different antibiotics. A dispenser delivers up to 12
disks simultaneously to the surface of an agar plate covered by a bacterial lawn.
During incubation, the drugs diffuse away from the disks into the surrounding agar and the
diameter of the zone of inhibition can be measured to determine drug susceptibility.
How do soaps, surfactants or detergents remove oils and grease? - Answer They have a
hydrophilic and hydrophobic end which is how they allow water to remove oils and grease and
help to lyse bacteria
What are quats and what do they do? - Answer NH₄-a quaternary amine and it is chaotropic
- disrupts cell membranes to kill bugs (bacteria).
Why do physicians add silver nitrate to a newborn's eyes? - Answer Heavy and transition
metals kills ions
Questions Solved Correct.
What does sepsis refer to? - Answer Microbial contamination-especially in the body.
What is aseptic technique? - Answer How to avoid microbial contamination-flaming, wiping
down surfaces, etc.
What is sterilization? - Answer Absence of all life
What is the difference in antiseptics and disinfectants? - Answer Antiseptics kill bacteria on
animal tissues.
Disinfectants kill bacteria on fomites.
What is the difference in bacteriostatic and bactericidal? - Answer Bacteriostatic stops
bacterial growth.
Bactericidal kills bacteria
What temperature, pressure, and how long do you have to use an autoclave to kill bacteria? -
Answer 121°
15 psi
15 min or more
When using an autoclave what must you do for solids? - Answer Use fast exhaust after 15
min
When using an autoclave what must you do for liquids? - Answer -Use slow exhaust up to
30-60 min
-Fill bottles no more than half way full
-Leave an inch between bottles
What type of growth can survive autoclave and how long can they survive? - Answer Prions
such as mad cow disease can survive 3 hrs of autoclaving, need high pH too while autoclaving to
kill them
, What is an alternative to autoclaving? - Answer Using dry heat on glass at 170° for more
than 2 hours
What do they use in hospitals to kill bacteria and how does it kill bacteria? - Answer Ethylene
oxide gas-alkylates microbial DNA to kill microbes
How is UV light use to kill microbes? - Answer UV at 254-260 nm is used for greater than 20
min forming thymine dimmers in DNA to stop replication and kill bacteria
What does HEPA stand for? - Answer High efficiency Particulate Air Filter
How do HEPA filters work? - Answer They have 0.3 µm pores and for liquids 0.22 to 0.45 µm
- these work because bacteria are 1-2 µm and cannot get through pores, but viruses and some
rickettsia or mycoplasmas can get through the pores
What did Peyton Rous do? - Answer He was the first to describe viruses as filterable agents
that cause plaques in mammalian cell cultures
What is one way to kill virtually ALL microbes? - Answer Ionizing Gamma and X-Rays
What does MIC stand for? - Answer Minimum Inhibitory Concentration-the lowest
concentration of a chemical which prevents visible growth of a bacterium
Describe the Kirby-Bauer or Disk diffusion tests - Answer The Kirby-Bauer assay uses a series
of round filter paper disks impregnated with different antibiotics. A dispenser delivers up to 12
disks simultaneously to the surface of an agar plate covered by a bacterial lawn.
During incubation, the drugs diffuse away from the disks into the surrounding agar and the
diameter of the zone of inhibition can be measured to determine drug susceptibility.
How do soaps, surfactants or detergents remove oils and grease? - Answer They have a
hydrophilic and hydrophobic end which is how they allow water to remove oils and grease and
help to lyse bacteria
What are quats and what do they do? - Answer NH₄-a quaternary amine and it is chaotropic
- disrupts cell membranes to kill bugs (bacteria).
Why do physicians add silver nitrate to a newborn's eyes? - Answer Heavy and transition
metals kills ions
