Sterilization and Disinfection

Question 1

Antisepsis

Answer 1

controlling the number of microorganisms and viruses

Question 2

Aseptic

Answer 2

No microbes in the environment

Question 3

-cide
-cidal

Answer 3

sudden death of microbe

Question 4

Degerming

Answer 4

removal of microbes by mechanical means through handwashing or alcohol swabbing of the site of infection

Question 5

Disinfection

Answer 5

reducing the number of pathogens to the point of where they no longer pose a threat of causing disease

Question 6

Sanitization

Answer 6

removal of pathogens from objects to meet public health standards

Question 7

Sterilization

Answer 7

destruction or removal of all microbes and viruses in or on an object

Question 8

Microbial death

Answer 8

permanent loss of reproductive ability under ideal environmental conditions

Question 9

Microbial death rates

Answer 9

often constant for a microorganism under particular set of conditions

Question 10

Alteration of cell walls and membranes - 1st mode of action of antimicrobial agents

Answer 10

cell wall must maintain integrity of the cell, however if damaged due to physical or chemical agents, then the cell bursts due to osmotic effects; therefore, the cytoplasmic membrane contents, cytoplasm and the control passages of chemical in or out of cell, leak out when damaged

Question 11

Damage to proteins and nucleic acids - 2nd mode of action of antimicrobial agents

Answer 11

protein functions on its 3D shape, however, extreme heat or chemicals can cause denature of proteins and changes shape causing cellular death; nucleic acids also can be altered or destroyed by chemicals, radiation, and heat by bringing about fatal mutations to the molecules; in addition, the interference of nucleic acids can also stop protein synthesis because of ribozyme

Question 12

Selection of Microbial Control Methods

Answer 12

ideally agents for the control of microbes should be inexpensive, fast-acting, stable during storage, and capable to controlling microbial growth while being harmless to humans, animals, and objects

Question 13

Site to be treated - factors affecting the efficacy of antimicrobial methods

Answer 13

harsh chemicals and extreme heat cannot be used on humans, animals, and fragile objects; method of microbial control based on site of medical procedure because the site can carry the potential for infections

Question 14

Susceptibilities of Microbes to Antimicrobial agents

Answer 14

Prions being the most resistant to enveloped viruses being the most susceptible

Question 15

High-level germicides

Answer 15

kill all pathogens, including endospores

Question 16

Intermediate level germicides

Answer 16

kill all fungal spores, protozoan cysts, viruses and pathogenic bacteria

Question 17

Low level germicides

Answer 17

kill vegetative bacteria, fungi, protozoa, and some viruses

Question 18

Environmental conditions - factors affecting the efficacy of antimicrobial methods

Answer 18

Temp and ph will affect microbial death rates and alter the efficacy of antimicrobial methods; organic materials such as fat, feces, blood, and vomit, can interfere with the penetration of heat, chemicals, and some forms of radiation, therefore may inactivate chemical disinfectants

Question 19

Factors that influence the action of antimicrobial agents - recap

Answer 19

the number and nature of microbes in the population, the temp and pH of the environment, the concertation of the agent, the more concentrated the better; the mode of action and the presence of solvents, interfering organic matter, and inhibitors.

Question 20

Biosafety Level 1

Answer 20

handling pathogens that do not cause disease in healthy

Question 21

Biosafety Level 2

Answer 21

handling moderately hazardous agents

Question 22

Biosafety Level 3

Answer 22

handling microbes in safety cabinets

Question 23

Biosafety Level 4

Answer 23

handling microbes that cause severe or fatal disease

Question 24

Moist Heat - Physical methods of microbial control

Answer 24

is used to disinfect, sanitize, sterilize, and pasteurize and kill cells by denaturing proteins and destroys cytoplasmic membranes; more effective than dry heat

Question 25

Boiling - Moist Heat

Answer 25

kills vegetative cells by bacteria and fungi, protozoan trophozoites, and most viruses, however, endospores, protozoan cysts, and some other viruses can survive boiling; the boiling time is critical, although different elevations in the atmosphere require different boiling times

Question 26

Autoclaving - Moist Heat

Answer 26

pressure applied to boiling water prevents steam from escaping; the boiling temp increases as pressure increses

Question 27

Pasteurization - moist heat

Answer 27

used for different kinds of diary products; it is not sterilization because some pathogens are heat-loving and heat-tolerant; there are batch, flash, ultra-high temp pasteurization

Question 28

Ultra-high temp sterilization

Answer 28

treated liquids can be stored at room temp, put on for 140 degrees celcius for 1 to 3 seconds and then rapid cooling

Question 29

Dry Heat

Answer 29

used for materials that cannot be sterilized with moist heat; denatures proteins and oxidizes metabolic and structural chemicals; air doesn't transfer heat like moist does; incineration is ultimate means of sterilization

Question 30

Refrigeration and freezing

Answer 30

decreases microbial metabolism, growth, and reproduction by having the chemical reactions slower at low temps and liquid water not available; however some microbes can multiply in refrigerated foods such as Listeria; slow freezing is more effective than quick freezing

Question 31

Desiccation

Answer 31

drying inhibits growth due to removal of water

Question 32

Osmotic pressure

Answer 32

high concentrations of salt or sugar in foods inhibit growth of microbes; cells in hypertonic solution of salt or sugar lose water; fungi have greater ability than bacteria to survive hypertonic environments

Question 33

Ionizing radiation

Answer 33

strike molecules, they have sufficient energy to eject electrons from atoms and creating ions; the ions disrupt hydrogen bonding, oxidize double covalent bonds, and create hydroxyl radicals; the ions also denature other molecules, particularly DNA, causing fatal mutations and cell death

Question 34

Filtration

Answer 34

the passage of a fluid though a sieve designed to trap particles, cells or viruses used to separate from the fluid

Question 35

Nonionizing radiation

Answer 35

does not have enough energy to force electrons out of orbit; includes UV light; suitable for disinfecting air, transparent fluids, and surfaces of objects

Question 36

Action of a Surfactant

Answer 36

in insoluble substance, dirt or grease, is being attached by surfactant molecules, found in cleaning products, and while rinsing our hands or a dish, it washes away the bacteria along with the surfactant molecule, doesn't necessarily kill it; decreases surface tension of water and disrupt cell membranes

Question 37

Phenol and Phenolics - Chemical methods of microbial control

Answer 37

denature proteins and disrupt cell membranes; it acts as a surfactant

Question 38

Alcohol - Chemical methods of microbial control

Answer 38

denature proteins and disrupt cytoplasmic membranes as long it has water with it; 70% alcohol will act better than 90%; acts as a surfactant

Question 39

Halogens - Chemical methods of microbial control

Answer 39

damage enzymes by denaturation of proteins; iodine tablets, iodophors, chlorine treatment, bleach, chloramines, and bromine disinfection will become loose ions that will cause the hydrogen to hook up to ions and cause to denature proteins

Question 40

Oxidizing Agents - Chemical methods of microbial control

Answer 40

kill by oxidation of microbial enzymes (denatures proteins); any oxidated solutions with oxygen will be able to denature proteins

Question 41

Quaternary ammonium compounds

Answer 41

are surfactant in which the hydrogen atoms of an ammonium ion are replaced by other functional groups or hydrocarbon chains

Question 42

Heavy metals - Chemical methods of microbial control

Answer 42

denature proteins by combining sulfur atoms with cysteine, an amino acid; some heavy metals are arsenic, zinc, mercury, silver, and copper

Question 43

Aldehydes - Chemical methods of microbial control

Answer 43

cross link functional groups to denature proteins and inactivate nucleic acids; glutaraldehyde disinfects and sterilizes; formalin used in embalming and disinfection of rooms and instruments

Question 44

Gaseous agents - Chemical methods of microbial control

Answer 44

denatures proteins and DNA by cross-linking functional groups by using ethylene oxide, propylene oxide, and beta-propiolactone

Question 45

Antimicrobial drugs

Answer 45

antibiotics, semisynthetic, and synthetic chemicals

Question 46

Use-dilution test - methods of evaluating disinfectants and antispetics

Answer 46

a researcher dips several metal cylinders into broth cultures of bacteria and briefly dries them at 37 degrees Celsius; Contaminated cylinder immersed into dilution of disinfectant; Cylinders removed, washed, and placed into tube of medium; Most effective agents entirely prevent growth at highest dilution