Chapter 9 - Chemical Methods of Microbial Control

Question 1

Antisepsis

Answer 1

reduction in the number of microbes + viruses on LIVING tissue

Question 2

Aseptic

Answer 2

refers to an environment/procedure free of pathogenic contaminants

Question 3

Disinfection

Answer 3

destruction of most microbes + viruses on NONliving tissues

Question 4

Sanitation

Answer 4

removal of pathogens from objects to meet public health standards

Question 5

-stasis / -static

Answer 5

suffixed indicating inhibition, but not complte destruction, or a type of microbe

Question 6

-cide / -cidal

Answer 6

suffixes indicating destruction of a type of microbe

Question 7

Sterilization

Answer 7

destruction of all microbes + viruses in/on an object

Question 8

Degerming

Answer 8

removal of microbes by mechanical means

Question 9

Action of Antimicrobial Agents

not marked

Answer 9

• alteration of cell walls + membranes
• nonenveloped viruses arre more tolerant of harsh conditions
• damage to proteins + nucleic acids

Question 10

Microbes from most resistant to most susceptible

Answer 10

Prions
Bacterial endospores
Mycobacteria
Cysts of protozoa
Active stage protozoa
gram-neg bacteria
Fungi
Nonenveloped virus
gram-pos bacteria
Enveloped virus

Question 11

3 methods of killing microbes

Answer 11

physical (heat, uv, fridge, freeze)
chemical (iodine, clorox)
biological (antibiotics)

Question 12

Effects of High Temp

Microbial Control

Answer 12

• breaks H bonds
• denatures proteins
• interferes w integrity of cytoplasmic membrane + cell wall
• disrupts structure + function of nucleic acids

Question 13

Thermal Death Point

Answer 13

lowest temp that kills all cells in broth in 10 mins

Question 14

Thermal Death Time

Answer 14

time to sterilize vol of liquid at set temp

Question 15

Autoclaving

Answer 15

• pressure applied to boiling water prevents steam from escaping
• boiling temp increases as pressure increases

Question 16

Autoclave conditions

Answer 16

121C, 15psi, 15 mins

Question 17

Pasteurization

Answer 17

• not sterilization (bc heat tolerant microbes survive)

- used for milk, ice cream, yogurt, fruit juices

Question 18

Pasteurization of milk

Answer 18

• batch method (145F for 30 mins)
• flash pasteurization (161F for 15 secs)
• ultrahigh-temp (UHT) pasteurization (191F for 1 sec, longest shelf life)

Question 19

Fridge + Freeze

Microbial Control

not marked

Answer 19

• decrease metab, growth, + preproduction
• psychrophilic microbes can multiply in refrigerated foods
• fridge halts growth of most pathogens
• slow freezing is better than quick

Question 20

Dessication

Answer 20

• Physical Method of Microbial Control
• drying INHIBITS growth bc removal of water

-static

Question 21

Lyophilization

Answer 21

• Physical Methods of Microbial Control
• for long term storage
• freezes bacteria that prevents formation of damaging ice crystals
• not for sterilization

Question 22

Ionizing Radiation

not marked

Answer 22

Physical Methods of Microbial Control

• wavelengths shorter than 1nanometer
• ejects electrons from atoms to create ions
• ions disrupt h bonding, oxidize double covalent, create hydroxide ions
• ELECTRON BEAMS
• GAMMA RAYS

Question 23

NONionizing radiation

Answer 23

• Physical Methods of Microbial Control
• wavelengths greater than 1nm
• excited electrons make new covalent bonds (affects 3D structure of proteins/nucleic acids)
• UV light causes pyrimidine dimers in DNA
• suitable for disinfecting air, transparent fluids, + surfaces of objects
• UV light doesnt penetrate well
• excited electrons make new covalent bonds (affects 3D structure of proteins/nucleic acids)

Question 24

Alcohol

Answer 24

• chem method of microbe control
• ANTISEPTIC + DISINFECTANT
• swabbing skin w 70% ethanol prior to injection (antiseptic)
• denatures proteins + disrupts cytoplasmic membranes
• more effective than soap in removing bacteria fr hands

Question 25

Oxidizing Agents

Answer 25

• chem method of microbial control
• peroxides, ozone, + peracetic acid
• kill by oxidation of microbial enzymes
• high level ANTISEPTIC + DISINFECTANT
• hydrogen peroxide can disinfect + sterilize surfaces (not useful for wounds)

Question 26

Effects of Dry Heat

Microbial Control

Answer 26

• used for materials that can’t be sterilized w moist heat
• denatures proteins + oxidizes metabolic + structural chemicals
• requires higher temp for longer time than moist heat
• incineration is ultimate means of sterilization

Question 27

most effective mean of disinfecting air and water

Answer 27

UV light

Question 28

Gaseous Agents

Answer 28

• chem microbial control

- • Microbicidal and sporicidal gases for sterilizing agents