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BACTE LEC > METHODS OF MICROBIAL CONTROL (DISINFECTION AND STERILIZATION)) > Flashcards

METHODS OF MICROBIAL CONTROL (DISINFECTION AND STERILIZATION)) Flashcards

1
Q
  • a Greek Physician (460-377 BC) Disproved the idea that disease was a punishment for sins
  • He advocated irrigation of wounds with wine or boiled water foreshadowing antisepsis
A

Hippocrates

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2
Q

a Greek Doctor who practiced medicine in Rome, boiled instruments used in caring wounded Roman gladiators.

A

Galen

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3
Q

a German Physician, and regarded as “saviour of mothers” who advocated the use of hand disinfection using chlorine lime solutions in obstetrics clinics. He is considered an early pioneer of antiseptic procedures.

A

Ignaz Semmelweiz

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4
Q

French Chemist and Microbiologist conducted
experiments that proved germs as causes of certain diseases

A

Louis Pasteur

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5
Q

a British Surgeon reduced the mortality rate of his patients by using a carbolic solution spray. He used it on wounds, on equipment in contact with wound, and on hands of the operating team.

A

Joseph Lister

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6
Q

What is the difference between
STERILIZATION and DISINFECTION?

A

Sterilization: Complete destruction of ALL FORMS of microbial life of including endospores. An All or nothing process

Disinfection: Elimination of a defined scope of microorganisms, including some endospores

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7
Q

What is the difference between
DISINFECTANT and ANTISEPTIC?

A

Disinfectant: Chemical agents applied to inanimate objects

Antiseptic: Chemical agents applied to the skin for the purpose of eliminating or reducing the number of bacteria present. It does not kill endospores.

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8
Q

Complete destruction of ALL FORMS of microbial life of including endospores. An All or nothing process

A

sterilization

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9
Q

Elimination of a defined scope of microorganisms, including some endospores

A

disinfection

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10
Q

Chemical agents applied to inanimate objects

A

Disinfectant

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11
Q

Chemical agents applied to the skin for the purpose of eliminating or reducing the number of bacteria present. It does not kill endospores.

A

Antiseptic

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12
Q

Microbial factors that contribute to their varied resistance

A

Endospores of bacteria
Cell wall of Mycobacteria
Viruses with lipid envelopes
Organisms that form biofilm
Prions

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13
Q

what will happen if there are presence of organic matter during disinfection

A

May inactivate disinfectants

May prevent full penetration and contact of disinfectant to the surface to be disinfected

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14
Q

The critical aspect in sterilization and disinfection

A

Contact time

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15
Q

factor that influence the degree of killing that has has a parallel relationship with effectiveness

A

temperature

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15
Q

Contact time can be influenced by:

A

▪ Bio burden of the material to be disinfectedor sterilized
▪ Type of microorganisms
▪ Presence of organic material
▪ Temperature at which the disinfectant is used

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16
Q

factor that influence the degree of killing that affects the effectiveness of a disinfectant

A

pH

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16
Q

disinfectants should be used at what temperature

A

20-22C

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17
Q

Disinfecting biofilms may require increased
disinfectant’s/sterilant’s:

A

▪ Concentration
▪ Contact time

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17
Q

factor that influence the degree of killing that is a community covered with a protective material that
shields them from external factors

A

Biofilm

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18
Q

what is the common mistake when using disinfectants

A

two disinfectants are better
than 1

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19
Q
  • Materials that invade sterile tissues or enter the vascular system
  • May produce infection if contaminated

What is the type of disinfection/sterilization?

A

Critical materials; Sterilization

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20
Q

Materials that come in contact with mucus membranes and non-intact skin

What is the type of disinfection/sterilization?

A

Semi-critical materials; High level disinfection agents

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21
Q

Iodine containing. Used at 0.1-0.2% concentration. Some iodine containing disinfectants can also be used as antiseptic agents.

What is the disinfection level and the agent used?

A

Low; Iodine

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21
Q

Objects that come in contact with intact skin but not mucus membranes

What is the type of disinfection/sterilization?

A

Non-critical materials; Intermediate to low level
disinfection

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22
Q

Biological detergent contains enzymes, non-biological does not. Used to remove soil and surface debris from items.

What is the disinfection level and the agent used?

A

Basic cleaning; Detergent

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23
Q

Used on hard surfaces as a disinfectant or on the skin as an antiseptic. Greater than 70% v/v solution required. Denatures cell membranes and dehydrates cells.

What is the disinfection level and the agent used?

A

Intermediate; Alcohol

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24
Q

10% concentration required. 2 types of bleach: CHLORINE AND PEROXIDE. Both peroxide and chlorine bleaches can corrode metal objects if left in contact for too long. Can irritate skin and mucous membranes.

What is the disinfection level and the agent used?

A

Intermediate to low; Bleach

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25
Q

0.2% concentration required for HLD. Corrosion of metal objects can occur with long contact time. Environmentally safe waste produced after processing.

What is the disinfection level and the agent used?

A

High to intermediate; Peracetic acid

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26
Q

0.2% concentration required for HLD. Can irreversibly bin proteins to the surface of processed objects, thorough washing required before sterilant treatment. Can irritate skin and mucous membranes.

What is the disinfection level and the agent used?

A

High; Glutaraldehyde

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27
Q

Enumerate the factors that influence the degree of killing

A

Concentration of disinfectants
Presence of organic matter
Nature of surface to be disinfected
Temperature
Contact time
pH
Biofilms
Compatibility of disinfectants

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28
Q

What method only destroys vegetative bacteria and what is its temperature and contact time?

A

Boiling; 100 degreed celsius, 10-15 minutes

29
Q

what is the temperature and contact time of autoclave for sterilization of culture media, utensils, glass pipettes, and instruments for assays

A

-121 degrees celsius, 15psi, 15 minutes

30
Q

Method that is the fastest and simplest method of sterilization that kills organisms, including spore-forming bacteria except PRIONS.

A

Autoclave

30
Q

What is the principle of autoclave

A

moist heat or steam under pressure

31
Q

what is the temperature and contact time of autoclave for decontamination of medical wastes and used instruments.

A

-132 degrees celsius, 15psi, 30-60 minutes

32
Q

what is the biologic indicator in autoclave

A

Geobacillus stearothermuphilus

32
Q

Method that is used in the sterilization of high-protein culture media such as Lowenstein Jensen medium for Mycobacteria

A

Inspissation

33
Q

Mode of action of inspissation

A

Thickens the medium through evaporation

34
Q

Method used to sterilize milk, dairy products, and alcoholic beverages, eliminates food borne pathogens and organisms responsible for spoilage, cannot eliminate bacterial spores.

A

Pasteurization

34
Q

Temperature and contact time of inspissation

A

75-85 degrees, 2 hours, 3 consecutive days

35
Q

Method that uses dry heat in killing microorganisms through protein denaturation. Suitable for the sterilization of heat-stable objects not penetrated by moist heat. Used to sterilize glasswares, oil products, petrolatum, or powders.

A

Oven

35
Q

Temperature and contact time of oven

A

160-170 degrees, 1.5-2 hours

35
Q

Method that is used in direct heating. Sterelizes inoculating loops and needles

A

Flaming

36
Q

Biologic indicator in oven

A

Bacillus subtilis var. niger

37
Q

Temperature for hazardous materials in Incineration

A

870-980 degrees celsius

37
Q

Most common method for treating infectious wastes and infected laboratory animal. Destroys prions. Burns materials into ashes at 300-400 degrees celsius.

A

Incerination

38
Q

Method used to control the spread of communicable diseases

A

Cremation

39
Q

Temperature in cremation

A

1800 degrees farehnheit (982 degrees celsius)

40
Q

Method of choice for the sterilization of heat-sensitive compounds or solutions such as antibiotic solutions, toxic chemicals, radioisotopes, vaccines and carbohydrates.

A

Filtration

41
Q

What type of filtration uses cellulose acetate/cellulose nitrate membrane with a vacuum

A

liquid filtration

41
Q

WHAT CHEMICAL METHOD?
- Precipitates bacterial protein
- Kills bacteria
- Irreversible

A

Bactericidal

41
Q

What type of filtration uses 0.45um and 0.80um pores membrane filters

A

Filtration of bacteria, yeast, and molds

41
Q

What type of filtration uses HEPA filters that remove organisms larger than 0.3um from isolation rooms, operating rooms, and biological safety cabinets.

A

Air filtration

41
Q

Method that uses low energy and is used to sterilize exposed surface air, operating rooms, biosafety cabinets, nurseries, and cafeterias.

A

Non-ionizing radiation

41
Q

Method that has a short wavelength, and has high energy. Destroys vegetative cells and endospores of both prokaryote and eukaryote cells. Used to sterilize disposable supplies.

A

Ionizing radiation

42
Q

WHAT CHEMICAL METHOD?
- Applied typically to the skin
- Inhibits sepsis formation

A

Antiseptic

42
Q

WHAT CHEMICAL METHOD?
- Applied to inanimate objects

A

Disinfectant

42
Q

WHAT CHEMICAL METHOD?
- Inhibits the growth of microorganisms
- Reversible

A

Bacteriostatic

42
Q

WHAT CHEMICAL METHOD?
MOA: inactivation of proteins and nucleic acids

Has irritable factor and carcinogenic - not recommended for routine disinfection and sterilization

A

Formaldehyde

43
Q

WHAT CHEMICAL METHOD?
MOA: inactivation of DNA or RNA

Rapid killing action, not activated by organic matter, but does not penetrate organic matter well.

Used as sterilant or disinfectant depending on the CONTACT TIME

A

glutaraldehyde

43
Q

WHAT CHEMICAL METHOD?
MOA: denaturation of protein, dissolution of lipid membrane, and dehydration of cells

Has excellent in-vitro activity against most gram-positive and gram-negative bacteria

Used both as antiseptic and disinfectant

A

Alcohol

44
Q

WHAT CHEMICAL METHOD?
MOA: Free iodine degrades microbial cell walls and cytoplasm, denatures and coagulates chromosomal materials.

Used as skin preparation agents for blood collection sites.

A

Halogens

45
Q

WHAT CHEMICAL METHOD?
MOA: antibacterial effect is attributed to the oxidative effects of hypochlorous acids formed when chloride ions are dissolved in water

Inexpensive and has a broad spectrum activity

Oldest and most commonly used disinfectants

A

Chlorine and chlorine compounds

46
Q

WHAT CHEMICAL METHOD?
MOA: destroys plasma membranes and denatures cell proteins

Has a broad spectrum activity, but not sporicidal

Effective in the presence of organic matter and remains active for long periods of time when applied on surfaces

The first widely used disinfectant and antispetic

A

Phenol and Phenolic compounds

46
Q

Most commonly used gas for sterilization

MOA: alkylation of nucleic acids in the spore and vegetative cells

A

Ethylene Oxide

46
Q

Active against all vegetative microorganisms and fungal spores

Used to sterilize medical equipment

A

Peracetic acid

46
Q

WHAT CHEMICAL METHOD?
MOA: disrupts cell membranes of bacteria resulting in leakage of cell contents

Used as surface-active agents

Inactivated by organic matter

A

Quaternary Ammonium Compounds

47
Q

Combined H2O2 and peracetic acid vapors is used in the pharmaceutical and medical devices industries.

A

Hydrogen peroxide and peracetic acid

48
Q

Active against all vegetative microorganisms, bacterial endospores, and fungal spores.

Used as sterilant in the pharmaceutical and medical devices industries.

A

Hydrogen peroxide

49
Q

Sporicidal disinfectants

A

Glutaraldehyde
Hydrogen peroxide
Ethylene oxide
Combined Hydrogen peroxide and peracetic acid

50
Q

Disinfectants inactivated by organic matter

A

Alcohol
Chlorine and Chlorine compounds
Quaternary Ammonium Compounds

51
Q

What number of biosafety level where organisms with known potential of infecting healthy individuals

A

BSL 1

52
Q

What number of biosafety level where organisms acquired through ingestion, percutaneous, and mucous membrane exposure

A

BSL 2

53
Q

What number of biosafety level where organisms possible for aerosol transmission

A

BSL 3

54
Q

What number of biosafety level where organisms that may expose extreme risk to laboratory workers and may cause life threatening disease

A

BSL 4

55
Q

Category where agents that pose the greatest health threat, easily transmitted, highly infectious, and high mortality rate

A

Category A

55
Q

Category where moderately easy to disseminate or transmit. Moderate morbidity and low mortality

A

Category B

56
Q

Category where organisms that can be engineered for mass destruction in the future. High mortality and morbidity rates.

A

Category C

BACTE LEC (7 decks)

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