CPA #15 Questions

Question 1

explain: hygiene hypothesis

Answer 1

exposure to everything can reduce infections; fewer childhood illnesses and increased personal hygiene have reduced children’s exposure to microbes so that when they do, the immune system overreacts and causes allergies

Question 2

what infectious agent does sterilization not apply to?

Answer 2

prions; standard sterilization techniques do not destroy them

Question 3

is commercially canned food free of microbes?

Answer 3

no; the commercial sterilization technique does not kill hyperthermophilic microbes because they do not cause disease and do not cause food to spoil at normal temp

Question 4

define: degerming

Answer 4

removal of microbes from a surface by scrubbing, such as when you wash your hands; the action of scrubbing is more important than the chemicals

Question 5

define: -stasis/-static

Answer 5

chemical agent that inhibits microbial growth/metabolism, but does not kill them

Question 6

define: -cide/-cidal

Answer 6

refer to agents that destroy or permanently inactivate microbe

Question 7

what are the two categories of antimicrobials?

Answer 7

1. those that disrupt the integrity of cells by adversely altering their cell walls or cytoplasmic membranes
2. those that interrupt cellular metabolism and reproduction by interfering with the structures of proteins and nucleic acids

Question 8

what are the 3 characteristics of ideal antimicrobials?

Answer 8

inexpensive, fast-acting, stable during storage

Question 9

what are the 3 factors when selecting a microbial control method?

Answer 9

1. relative susceptibility of microbes
2. environmental conditions
3. site to be treated

Question 10

define: high-level germicide

Answer 10

kill all pathogens (excluding prions), including bacterial endospores; healthcare professionals use them to sterilize invasive instruments

Question 11

define: intermediate-level germicide

Answer 11

kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria, but not endospores

Question 12

define: low-level germicides

Answer 12

eliminate vegetative bacteria, fungi, protozoa, and some viruses; used to disinfect items that contact only the skin of patients (furniture, electrodes)

Question 13

what agency established the biosafety levels?

Answer 13

Center for Disease Control and Prevention (CDC)

Question 14

define: biosafety level-I (BSL-I)

Answer 14

suitible for handling microbes, such as E. coli, not known to cause disease in healthy humans; precautions are minimal; include hand-washing with antibacterial soap and disinfecting surfaces

Question 15

define: BSL-II

Answer 15

designed for handling moderately hazardous agents, such as hepatitis and influenza viruses, methicillin-resistant S. aureus; precautions taken with contaminated sharps and aerosol producing procedures

Question 16

define: BSL-III

Answer 16

all manipulations be done inside safety cabinets with HEPA filters; TB, yellow fever, Rocky Mountain Spotted Fever, anthrax

Question 17

define: BSL-IV

Answer 17

“space suits”; separate buildings for testing; fatal diseases; ebola, smallpox, lassa fever viruses

Question 18

why is heat used for microbial control?

Answer 18

high temps denature proteins, interfere with integrity of cytoplasmic membrane/cell walls, and disrupt the function of nucleic acids

Question 19

define: moist heat

Answer 19

commonly used to disinfect, sanitize, sterilize, pasteurize; more effective than dry heat because water is a better conductor of heat than air

Question 20

define: autoclave

Answer 20

pressure chamber; pipes introduce and evacuate steam; valves remove air and control pressure

Question 21

define: pasteurization

Answer 21

thermoduric and thermophilic prokaryotes survive; combination of time and temperature, varies by product;

Question 22

how is cold used to control microbial growth?

Answer 22

halts/slows down growth for mesophiles

Question 23

does freezing eliminate bacteria?

Answer 23

no, because it just slows down the metabolism, does nothing to inactivate the pathogen

Question 24

define: desiccation

Answer 24

aka drying; preserves foods such as fruits, beans, grains, etc; inhibits growth because metabolism requires liquid water

Question 25

define: lyophilization

Answer 25

combines freezing and drying; preserves microbes for many years; liquid nitrogen or frozen carbon dioxide; vacuum removes frozen water; prevents the formation of large, damaging ice crystals

Question 26

passage of fluid through a sieve to trap microbes and separate them from the fluid; used to sterilize heat-sensitive materials

Answer 26

Filtration

Question 27

how do hypertonic solutions inhibit microbe growth?

Answer 27

high concentrations of salt/sugar in foods; osmotic pressure (area of high conc. to an area of low conc.); removal of water inhibits cellular metabolism

Question 28

define: ionizing radiation

Answer 28

electron beams, gamma rays, some x-rays; wavelength shorter than 1 nm; they have sufficient energy to eject electrons from atoms, creating ions; ions disrupt hydrogen bonds, oxidize double covalent bonds, and create highly reactive hydroxyl groups; these ions denature other molecules, particularly DNA, causing fatal mutations and death

Question 29

define: nonionizing radiation

Answer 29

electromagnetic radiation with a wavelength greater than 1 nm; does not have enough energy to force electrons out of orbit and cause new covalent bonds effecting 3D shape; UV, visible light, infrared radiation, radio waves

Question 30

dips several metal cylinders into broth cultures and briefly dries them at 37C; immerses each container into different dilution of the disinfectant; after 10 minutes, each cylinder is removed, rinsed, and placed into a sterile medium for 48 hours

Answer 30

use-dilution

Question 31

add a suspension of bacterium to a suitable concentration of the chemical being tested; at predetermined times, samples are moved into a growth medium containing disinfectant deactivator; after 48 hours, turbidity in medium determines effectiveness of treatment and bacteria survival

Answer 31

kelsey-sykes capacity test

Question 32

time consuming and realistic; swabs are taken from actual objects before and after a disinfectant treatment; swabs are inoculated into appropriate growth media

Answer 32

in-use test

Question 33

explain Paul Ehrlich

Answer 33

arsenic compounds to fight syphyllis; chemotherapy

Question 34

explain Alexander Fleming

Answer 34

penicillin

Question 35

explain Gerhard Domagk

Answer 35

sulfanilamide; treats wide array of bacterial infections

Question 36

define: selective toxicity

Answer 36

effective microbial agent must be more toxic to a pathogen than to the pathogen host