Week 13 Exam 4

Question 1

Sterilization

Answer 1

removal or destruction of ALL microbes on an object

-autoclave

Question 2

disinfection

Answer 2

use of physical or chemical agents to inhibit or destroy microorganisms on surface or objects

• may or may not be free of pathogens
• bleach

Question 3

decontamination/sanitization

Answer 3

disinfect object used by public to reduce number of pathogens

• utensils
• detergents

Question 4

Antisepsis/degermation

Answer 4

removal of microbes by scrubbing

-surgical hand scrubs

Question 5

relative resistance

Answer 5

primary targets are microorganisms capable of causing disease or spoilage
-not all are easy to control

Question 6

Most resistant

most susceptible

Answer 6

-

Question 7

bactericidal

cide/cidal

Answer 7

killing microbes

kills bacteria

Question 8

static/stasis

bacteriostatic

Answer 8

reduction of growth

limit growth of bacteria (antibiotics)

Question 9

sepsis

Answer 9

growth of microorganisms in the blood and other tissues

Question 10

antisepsis

Answer 10

chemicals used on skin or tissue to inhibit or destroy microbes

Question 11

antiseptics

Answer 11

chemical agents applied to exposed body surfaces, wounds, and surgical incisions to prevent vegetative pathogens

Question 12

microbial death

Answer 12

permanent loss of reproductive capability, even under optimal growth conditions

Question 13

death rate

Answer 13

death rate can be used to measure action of microbial agent

Question 14

how to pick which antimicrobial to use?

5 steps

Answer 14

1. Must be: inexpensive, fast-acting, capable of controlling growth, harmless to human/animal/surface
2. site to be treated: chemicals and heat can’t be used on living subjects or fragile objects
3. susceptibility of microbes
4. number of microorganisms
5. concentration of agent

Question 15

Environmental conditions

Answer 15

• warm disinfectants: work better than cool, reactions are faster at higher temps
• acidic conditions: enhance antimicrobial effect of heat
• organic material: interfere with penetration of heat or chemicals

Question 16

how do antimicrobials work?

Answer 16

• alter cell wall and membrane: damaged cell wall=osmotic stress/damaged membrane=cellular contents leak out
• damage proteins and nucleic acids: denature proteins & alter/destroy nucleic acids

Question 17

physical methods of microbial control

Answer 17

• temp: boil, autoclave, pasteurization, incineration, ultra high temp sterilization, refrigeration freezing
• water: osmotic pressure, desiccation & lyophilization
• size: filtration
• other: radiation

Question 18

microbial resistance

Answer 18

• bacterial endospores: exhibit greatest resistance, autoclaves usually run 121 degrees C for 15 min
• vegetative cells:
• fungi, protozoa, and worms are similar in their sensitivity to heat
• viruses are resistant to heat

Question 19

Chemical methods of microbial control

Answer 19

• phenol & phenolics: denature proteins & disrupt cell membrane
• alcohols: intermediate level disinfectant, denature proteins, disrupt cytoplasmic membrane (H20 is required)
• halogens: Cl, I, B, Fl intermediate level, damages proteins
• oxidizing agents: ozone, peroxide, peraetic acid are high level disinfectants, kills by oxidation of microbial enzymes
• surfactants: reduce surface tension of solvents, includes soaps, detergents, disrupts cellular membranes, low level disinfectants
• heavy metals: low level bacteriostatic, denatures proteins
• enzymes: controls microbes in environment (lysosome digest peptidoglycan, prionzyme removes prions from medical instruments)

Question 20

high
intermediate
low

Answer 20

• high level germicide: kills all pathogens including endospores
• intermediate level germicide: kills fungal spores, protozoan cysts, viruses & pathogenic bacteria
• low level germicide: kills vegetative bacteria, fungi, protozoa, some viruses

Question 21

factors affecting germicidal activity

Answer 21

nature of the microorganisms being treated
nature of the material being treated
degree of contamination
time of exposure
strength & chemical action of the germicide (dilutions/concentrations)

Question 22

2017 ban

Answer 22

in 2016, FDA banned 19 active ingredients in consumer products
many of the ingredients can select for resistance in microbes-proliferation of antimicrobial resistant organisms
-iodophors
-many phenols(triclosan & triclocarbon)
-some quats
soaps and detergents are sufficient for human use

Question 23

biosafety levels

Answer 23

• BSL-1: handling microbes hat don’t cause disease in humans, precautions: hand washing w/ antibacterial soap & washing surfaces with disinfectants
• BSL-2: handling modernity hazardous agents
• BSL-3: all manipulations of microbes done in safety cabniets
• BSL-4: handling microbes that cause severe/fatal disease, lab is isolated & personnel wear protective suits

Question 24

methods for evaluating disinfectants & antiseptics

Answer 24

• use-dilution test: metal cylinders dipped into broth cultures of bacteria, contaminated cylinder immersed into dilution of disinfectant, cylinders removed, washed, & placed into tube of medium, most effective agents entirely prevent growth at highest dilution, current standard test in US
• kelsey-sykes capacity test: bacteria are added to chemical being tested
• in-use test: swabs taken before and after application of disinfectant or antiseptic, media added to swabs, incubated for growth