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3 DVM - MICROBIO > LESSON 13: CONTROL MICROORGANISM > Flashcards

LESSON 13: CONTROL MICROORGANISM Flashcards

1
Q

Ubiquitous and many microorganisms are associated with
undesirable consequences, such as food spoilage and disease.

A

MICROBES

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2
Q

it is essential to kill a wide variety of microorganisms or inhibit their growth to minimize
their destructive effects. The goal is twofold:

A

: (a) to destroy pathogens and prevent
their transmission and
(b) to reduce or eliminate microorganisms responsible for the
contamination of water, food, and other

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3
Q

Microorganisms are controlled
either by
physical agents (temperature, desiccation, osmotic pressure, radiation, and
filtration) or

Chemical agents (disinfectants, antiseptics, antibiotics, and chemotherapeutic antimicrobial chemicals).

A
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4
Q

a process by which an article, surface, or medium is freed of all
living microorganisms either in the vegetative
or in the spore state.

A

Sterilization

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5
Q

any material that has been subjected to the above process.

A

Sterile

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6
Q

A chemical agent that is used to perform sterilization because of their ability y to destroy spores.

A

STERILANTS

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7
Q

also called a microbicide,
is any chemical agent that kills pathogenic
microorganisms either on inanimate (nonliving) materials or on living tissue but not resistant microbial.

A

Germicide

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7
Q

the use of a chemical agent that destroys or removes all pathogenic organisms or organisms capable of giving rise to infection or its harmful products (toxin) thus destroys vegetative pathogens but not bacterial endospores.

A

Disinfection

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8
Q

Used only on inanimate objects because they can be toxic to human and other animal tissue, when used in HIGHER CONCENTRATION

A

Disinfectant

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9
Q

Defined as the growth of microorganisms in the body or the presence of
microbial toxins in blood and other tissues

A

Sepsis

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10
Q

refers to any practice that prevents the entry of infectious agents into
sterile tissues and thus

A

Asepsis

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11
Q

s any cleansing technique that mechanically removes
microorganisms (along with food debris) to reduce the

A

Sanitization

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11
Q

e chemical agents applied directly to the exposed body surfaces
(e.g., skin and mucous membranes), wounds, and surgical incisions to destroy or
inhibit vegetative pathogens

A

Antiseptics

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12
Q

process usually involves scrubbing the skin or
immersing it in chemicals, or both. It also emulsifies oils that lie on the outer
cutaneous layer and mechanically removes potential pathogens from the outer
layers of the skin.

A

Degerming/antisepsis

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12
Q

a compound (e.g., soap or detergent) that is used to perform
sanitization.
Air sanitization with ultraviolet lamps reduces airborne microbes in
hospital rooms, veterinary clinics, and laboratory installations.

A

Sanitizer

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13
Q

Examples of degerming procedures are
(a) surgical hand scrub,
(b)
application of alcohol wipes to the skin, and
(c) cleansing of a wound with germicidal
soap and water

A
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14
Q

STERILIZATION
Classified into:2.
1. Physical methods
2. Chemical method

A
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14
Q

Methods of controlling microorganism

A
  1. Sterilization
  2. Disinfection
  3. Antimicrobials
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15
Q

Physical methods of sterilization

A
  1. Sunlight
  2. Heat
  3. Filtration
  4. Radiation
  5. Sonication
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16
Q

natural method of sterilization of water in tanks, rivers, and lakes.

A

Sunlight

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17
Q

Direct sunlight has an active germicidal effect due to its content of ultraviolet and heat rays.

A
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18
Q

Bacteria present in natural water sources are rapidly destroyed by exposure to sunlight.

A
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19
Q

One of the most dependable method of sterilization.

A

Heat

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20
Q

higher
temperatures (exceeding the maximum) are microbicidal, whereas
lower
temperatures (below the minimum) tend to have inhibitory or microbiostatic
effects.

A
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21
Q

Two types:
moist and dry heat.

A
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22
Q

Sterilization by moist heat occurs

A

Hot water, boiling water, or
steam (vaporized water) and the temperature usually ranges from 60 to
135°C. M

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22
Q

Moist heat kills microorganisms by

A

denaturation and coagulation of
proteins.

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23
Q

Classification of moist heat:

A
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24
Q

Sterilization at a temperature below 100°C: example is Pasteurization

A
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25
Q

A technique in which heat is applied to liquids to kill
potential agents of infection and spoilage, while at the same time
retaining the liquid’s flavor and food value.

A

Pasteurization

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26
Q

This method is extensively
used for sterilization of milk and other fresh beverages, such as fruit
juices, beer, and wine which are easily contaminated during collection
and processing.

A

pasteurization

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27
Q

Pasteurization has two methods:

A

Flash method and Holder method

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27
Q

(product is exposed to heat at 72°C for 15–20 seconds followed by a
sudden cooling to 13°C or lower)

A

Flash method

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28
Q

(product is
exposed to a temperature of 63°C for 30 minutes followed by cooling to
13°C or lower, but not less than 6°C).

A

Holder method

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29
Q

Pasteurization inactivates most viruses and destroys the vegetative stages of
97–99% of bacteria and fungi, it does not kill endospores or thermoduric species
(mostly nonpathogenic lactobacilli, micrococci, and yeasts)

A
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30
Q

Sterilization at a temperature of 100°C: includes
(a) boiling and
(b) steam sterilizer

A
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31
Q

Of water for 10–30 minutes kills most of the vegetative forms of bacteria but not bacterial spores thus only for disinfection.

A

Boiling

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32
Q

At 100°C: substances are exposed to steam at
atmospheric pressure for 90 minutes during which most vegetative
forms of the bacteria except for the thermophiles are killed by the moist
heat.

A

Steam sterilizer

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33
Q

pasteurization inactivates
most viruses and destroys the vegetative stages of 97–99% of bacteria
and fungi, it does not kill endospores or thermoduric species (mostly
nonpathogenic lactobacilli, micrococci, and yeasts).

A

Sterilization at a temperature above 100°C:

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34
Q

Certain heat-labile substances (e.g., serum, sugar, egg, etc.) that cannot withstand the high temperature of the
autoclave can be sterilized by a process of intermittent sterilization, known as

A

Tyndallization

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35
Q

used most often to
sterilize heat-sensitive culture media, such as those containing sera (e.g., Loeffler’s serum slope), egg (e.g., Lowenstein–Jensen’s medium), or
carbohydrates (e.g., serum sugars) and some canned foods.

A

Intermittent sterilization

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36
Q

Process of Tyndallization

A

Carried out over a period of 3 days and
requires a chamber to hold the materials and a reservoir for boiling water.
Items to be sterilized are kept in the chamber and are exposed to free to flowing steam at 100°C for 20 minutes, for each of the three consecutive
days

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37
Q

1st day:

A

: the temperature is adequate to kill all the vegetative forms of the
bacteria, yeasts, and molds but not sufficient to kill

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38
Q

2nd day:

A

The surviving spores are allowed to germinate to vegetative
forms on the second day and are killed on re-exposure to steam.

39
Q

3rd day:

A

Re-ensures killing of all the spores by their germination to
vegetative forms

40
Q

Makes use of air with a low moisture content that has been heated by a flame or electric heating coil. In practice, the temperature of dry heat ranges from 160°C to several thousand degrees Celsius.

A

Sterilization by dry heat

41
Q

kills microorganisms by protein denaturation, oxidative damage, and the toxic effect of increased level of electrolytes.

A

Dry heat

42
Q

Sterilization of inoculating loop or wire, the tip of forceps, searing spatulas, etc., is carried out by holding them in the flame of the
Bunsen burner till they become red hot.

A
43
Q

Glass slides, scalpels, and
mouths of culture tubes are sterilized by passing them through the
Bunsen flame without allowing them to become red hot.

A
44
Q

Excellent method for safely destroying
infective materials by burning them to ashes

A

Incineration

45
Q

Electrically heated and is fitted with a
fan to ensure adequate and even distribution of hot air in the chamber.

A

Hot air oven

46
Q

remove contaminating microorganisms from solutions rather than
directly destroying them.

A

Filters

47
Q

The filters are of two types:

A

(a) depth filters;
ex: candle filter, asbestos filter or sintered glass filters

(b) membrane filters;
ex: cellulose acetate, cellulose nitrate, polycarbonate, polyvinylidene fluoride, or other
synthetic materials made

48
Q

An excellent sterilizing agent
with very high penetrating power.

These radiations penetrate deep into objectsand destroy bacterial endospores and vegetative cells, both prokaryotic and
eukaryotic but not that effective against viruses.

A
49
Q
A
50
Q

Example: (a) X-rays, (b) gamma
rays, and (c) cosmic rays

A
51
Q

from a cobalt-60 source is used for
sterilization of antibiotics, hormones, sutures, catheters, animal feeds, metal foils, and plastic disposables, such as syringes, meat and other food items.

A

Gamma radiation

52
Q

Irradiation usually kills

A

Escherichia coli O157:H7, Staphylococcus aureus,
Campylobacter
jejuni, and other pathogens.

53
Q

Since there is no detectable increase of
temperature in this method, this method is commonly referred to as

A

“cold sterilization.”

54
Q

While nonionizing radiations include infrared and

A
55
Q

Use of high-frequency sound (sonic) waves beyond the sensitivity
of the human ear are known to disrupt cells. Sonication transmits vibrations
through a water-filled chamber (sonicator) to induce pressure changes and create intense points of turbulence that can stress and burst cells in the vicinity.

A

Sonication

56
Q

Heat generated by the sonic waves (up to 80°C) also appears to contribute to the antimicrobial
action.

A
57
Q

Gram-negative rods are most sensitive to ultrasonic vibrations.

A
58
Q

Gram-positive cocci, fungal spores, and bacterial spores are resistant to them

A
59
Q

The process of inactivating microorganisms by direct exposure to chemical or
physical agents.

A

DISINFECTION

59
Q

products or biocides that destroy or inhibit the growth of
microorganisms on inanimate objects or surfaces

A
60
Q

Disinfectants can be sporistatic
but are not necessarily sporicidal.

A
61
Q

are biocides or products that destroy
or inhibit the growth of microorganisms

A

Antiseptics

62
Q

9 Properties of ideal disinfectant

A
  1. It should have a wide spectrum of antimicrobial activity.
  2. It should act in the presence of organic matter.
  3. It should not be toxic to human or corrosive.
  4. It should be stable upon storage and should not undergo any chemical
    change.
  5. It should be odorless or with a pleasant odor.
  6. It should be soluble in water and lipids for penetration into microorganisms.
  7. It should be effective in acidic as well as in alkaline media.
  8. It should have speedy action.
  9. If possible, it should be be relatively inexpensive.
63
Q

Action of Disinfectants

A
  1. They produce damage to the cell wall and alter permeability of the cell
    membrane, resulting in exposure, damage, or loss of the cellular contents.
  2. They alter proteins and form protein salts or cause coagulation of proteins.
  3. They inhibit enzyme action and inhibit nucleic acid synthesis or alter nucleic
    acid molecules.
  4. They cause
64
Q

Factors Influencing Activity of Disinfectants

A
  1. temperature
  2. types of microorganism
  3. physiological state of the cell
  4. environment
64
Q
A
65
Q
  1. temperature
A

Increase in temperature increases the efficiency of
disinfectants.

66
Q

Vegetative cells are more susceptible than spores.
Spores may be resistant to the action of disinfectants.

A

Type of microorganism:

67
Q

: Young and metabolically active cells are more
sensitive than old dormant cells. Non growing cells

A

. Physiological state of the cell:

68
Q

The physical or chemical properties of the medium or substance
influence rate as well as efficiency of disinfectants, e.g., pH of the medium and
presence of extraneous materials.

A

Environment

69
Q

most widely used antiseptics and disinfectants in
laboratories and hospitals worldwide.
They are bactericidal or bacteriostatic and
some are fungicidal also.
They act by denaturing proteins and disrupting cell
membranes.
They are effective in the presence of organic material and remain
active on surfaces long after application. E

A
70
Q

Examples

A
  1. phenol
  2. Crerol
  3. Halogenated diphenyl compounds
71
Q

is effective against
vegetative forms of bacteria but not suitable for application to skin or mucous
membrane),

A

Phenol

72
Q

(are more germicidal and less poisonous than phenol but
corrosive to living tissues.
They are used for cleaning floors (1% solution), for
disinfection of surgical instruments, and for disinfection of contaminated objects.

A

cresol

73
Q

is a solution of cresols in soap)

A

Lysol

74
Q

s (like
hexachlorophene and chlorhexidine
are highly effective against both Gram- positive and Gram-negative bacteria.

A
75
Q

They are used as skin antiseptics and for
the cleaning of wound surfaces especially hexachlorophene because once
applied it persists on the skin and reduces growth of skin bacteria for longer
periods.

A
76
Q

It can cause brain damage and is now used in hospital
nurseries only after a staphylococcal outbreak)

A
77
Q

Are fluorine, bromine, chlorine, and iodine—a group of
nonmetallic elements that commonly occur in minerals, sea water, and salts.

A

Halogens

78
Q

kills not only bacterial cells and endospores but also fungi and viruses

A

chlorine

79
Q

at a concentration of 0.6–1.0 part of chlorine per million parts of
water makes water potable and safe to use.

A

Chlorination

80
Q

chlorine is ineffective at
an alkaline pH, less effective in the presence of excess organic matter,
and
relatively unstable, if exposed to light.

A
81
Q
A
82
Q

rapidly
penetrates the cells of microorganisms,
where it apparently disturbs a variety of
metabolic functions by interfering with the hydrogen and disulfide bonds of
proteins.

not adversely affected by organic matter and
pH.

A

Iodine

83
Q

most widely used disinfectants and antiseptics effective at a
concentration of 60–70% in water.
They are bactericidal and fungicidal but not
sporicidal or virucidal.

A

alcohol

84
Q

are the two most
popular alcohol germicides.
They act by denaturing bacterial proteins and
possibly by dissolving membrane lipids.

A

Ethyl alcohol
Isopropyl alkohol

85
Q

Is effective against fungal spores.

A

Methyl alcohol

86
Q

: are highly reactive molecules that combine with nucleic and
alkylating molecules; sporicidal and can be used as chemical sterilants.

A

aldehydes

87
Q

That is usually dissolved in water or alcohol before use against
bacteria, spores and viruses.

A

Folmaldehyde

88
Q

Is 40% aldehyde in aqueous
solution.
It is used to:
1. preserve fresh tissue specimens,
2. destroy anthrax spores
in hair and wool,
3. prepare toxoids from toxins,
4. sterilize bacterial vaccines, and
5. kill bacterial cultures

A

Formalin Solution

89
Q

used for sterilization of large volume of heat-sensitive disposable
items and also instruments

A

Gases

90
Q

frequently used gaseous agents

A

Ethylene oxide,
formaldehyde gas, and

betapropiolactone

91
Q

: such as detergents are the substances that alter
energy relationship at interfaces producing a reduction in surface tension.

A
92
Q

are organic molecules that serve as wetting agents and emulsifiers
because they have both polar hydrophilic and nonpolar hydrophobic ends thus
are very effective cleansing agents

A

Surface active agents:

93
Q

They are different from soaps, which are
derived from fats. Four types:

A

: (i) Cationic surface active agents ex: quaternary
ammonium compounds,
(ii) Anionic surface active agents, ex: soap made from
saturated or unsaturated fatty acids,
(iii) Nonionic surface active agents (not
effective),
(iv) Amphoteric or ampholytic compounds

94
Q

This group includes halogens, hydrogen peroxide, potassium permanganate, and sodium perborate. They are good disinfectants
and antiseptics but are
less effective in the presence of organic matter.

A

Oxidizing agents

95
Q

used extensively as skin and wound antiseptics include
(a) acridine
dyes and
(b) aniline dyes both more active against Gram positive bacteria

A

Dyes

96
Q

Soluble salts of mercury, silver, copper, arsenic, and other
heavy metals have antibacterial activity, both bactericidal and bacteriostatic. They combine with proteins, often with their sulfhydryl groups and inactivate
them or may also precipitate cell proteins.

A

Heavy metals:

97
Q

(such as sulfuric acid, nitric acid, hydrochloric acid, and benzoic acid) a

A

acids

98
Q

(like potassium and sodium hydroxide and
ammonium hydroxide) are germicidal in nature.

A

alkalis

99
Q

They kill microorganisms by
hydrolysis and altering the medium

A

acids and alkalis

100
Q
A

3 DVM - MICROBIO (15 decks)

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