Control of Microbial Growth Lecture Flashcards
1
Q
reducing or eliminating microbial
population.
A
microbial control
2
Q
range from complete eradication of
microorganisms to the mere inhibition of
their growth, and the goal of the
treatment will influence the control
method chosen.
A
microbial control
3
Q
only reduces the microorganisms
A
boiling
4
Q
- the complete removal of all life forms from a given surface by
any method. Absolute
A
sterilization
5
Q
- Treatment of an object or surface to make it safe to handle
and free from disease transmission
A
decontamination
6
Q
reduction in the number of pathogenic microorganisms to the
point where they no longer pose a threat of disease. s
A
disinfection
7
Q
- Less lethal process than sterilization.
A
disinfection
8
Q
a chemical agent used in inanimate objects.
A
disinfectant
9
Q
- a chemical agent used in human tissue to
prevent infection.
A
antiseptic
10
Q
used on skin
A
antiseptic
11
Q
- removal of microbes from limited area
A
degerming
12
Q
- kills microbes
A
biocide/germicide
13
Q
- only inhibits growth, not killing
A
bacterostasis
14
Q
freezing is an example of what kind of microbial control
A
bacteriostasis
15
Q
Reduce the number of pathogens to an acceptable levels for
public health
A
sanitation
16
Q
refers to microbial contamination.
A
sepsis
17
Q
is the absence of significant contamination.
A
asepsis
18
Q
Removal of pathogens from living tissue
A
antisepsis
19
Q
techniques prevent microbial contamination of
wounds.
A
aseptic surgery
20
Q
effectiveness of antimicrobial treatment depends on (6)
A
Number of microbes and microbial characteristics
§ Presence of organic load such as pus, blood,
sputum and others.
§ Time of exposure
§ Type of materials to be decontaminated.
§ Method of microbial control appropriate to the
material.
§ Capacity of the facility
21
Q
material with antimicrobial properties
A
copper
22
Q
material that is resistant to corrosion
A
stainless steel
23
Q
most resistant to least resistant
A
prions
endospores of bacteria
mycobacteria
cyst of protozoa
vegetative protozo
gram - bacteria
fungi including most fungal forms
virus without envelopes
gram + bacteria
virus with lipid envelopes
24
Q
when to decontaminate?
A
§ Before and after using equipment and work surfaces.
§ Before disposing infectious materials such as gauze, wound
dressing, syringes, disposable lab materials used in
microbiology lab.
§ Before re-using re-usable materials.
25
common modes of action of methods of control (3)
Damage to plasma
membrane of pathogen
(bacteria, fungi,
protozoa)
Denaturation of cellular
proteins of the pathogen
Damage to DNA of the
pathogen
26
physical methods of control
temperature
radiation
filtration
reduction of water activity
27
temp of >500C, Vaporizes organic material on nonflammable
surfaces but may destroy many substances in
the process
incineration
28
temp of 100 C, Thirty minutes of boiling kills vegetative forms of
bacteria but may not kill bacterial endospores.
There are also toxins that are not inactivated at
100C.
Boiling
29
100 C, Three 30-minute intervals of boiling, followed by
periods of cooling kills bacterial endospores.
intermittent boilding
30
121 C for 15 minutes at 15 p.s.i
Kills all forms of life including bacterial endospores.
The substance being sterilized must be
maintained at the effective temperature for the
entire time
autoclave and pressure cooker
31
160 C for 2 hours/150 C for 150
minutes.
Used for materials that must remain dry. Good for
glassware, metal, but not most plastic or
rubber items.
dry heat (hot air oven)
32
170 C for 1 hour
Same as above. Note that increasing the
temperature by 10 C shortens the sterilizing
time by 50 %.
Dry heat (hot air oven)
33
63-66 C for 30 minutes
Kills most vegetative bacterial cells, including
pathogens such as streptococci, staphylococci
and Mycobacterium tuberculosis.
pasteurization (batch method)
34
72 C for 15 seconds
Effect on bacterial cells is similar to batch method.
For milk, this method has fewer undesirable
effects on quality or taste
pasteurization (flash methods)
35
Most dependable for decontamination
autoclave
36
the autoclave is filled with steam to a pressure of ____ resulting in a temperature of ___
15-17 psi
121 C
37
hazards of autoclaving for sterilization
Explosive breakage of glass vessels during opening
and unloading.
§ Burns
§ Destruction of materials due to pressure and/or heat.
38
For materials that can be damaged by moist
heat or are impenetrable to moist heat.
dry heat sterilization
39
denatures proteins- autoclave: Steam under pressure
what kind of heat
moist heat
40
kills by oxidation
dry heat sterilization
41
reduces spoilage organisms and pathogens
pasteurization
42
refrigeration temperature
0-7
43
stops all microbial growth.
low temperature
deep freezing
44
Not damaging to most microorganisms
and, when brought up to suitable
temperatures, the microbes will begin
growing again.
low temperature
45
Microorganisms preserved in liquid
nitrogen is in what temp
-196
46
Destroys microorganisms with
high-energy electromagnetic
waves such as gamma rays, Xrays, UV light or electron
beams.
radiation
47
At high levels, ____ rays and
___ rays can denature proteins.
gamma
xrays
48
At lower doses, gamma rays
and X-rays collide with various
molecules (often water),
producing highly reactive
species, such as ____ and
___ radicals.
hydroxyl
hydride
49
uses shorter wavelengths i.e.
gamma rays, X-rays, or electron beams
ionizing radiation
50
Principal effect is ionization of water forming hydroxyl radicals
ionizing radiation
51
* UV-C irradiation at wavelength 280 to 100 nm.
non ionizing radiation
52
UV Radiation with longest to shortest nm
UVA
UVB
UVC
53
UV that causes premature aging, wrinkling of skin, implicated in skin cancer
UVA
54
UV that causes skin cancer, cataracts, sunburn
UVB
55
UV that is extremely dangerous, blocked by the ozone layer
UVC
56
source of radiation
cathode ray tubes
57
use of radiation
Sterilization and decontamination in medical supplies and
food industries.
* Food preservation
58
– kill by heat; not antimicrobial
what electromagnetic wave
microwaves
59
remove of microbes from heat-sensitive
compounds such as antibiotics and vitamins.
filtration
60
Physically removes microbes by employing
membranes whose pores are too small to allow
their passage.
filtration
61
Does not effectively remove viruses from
solution
filtration
62
example of filtration method control
filter sterilization
63
§ Uses the principle of filtration
facemasks
64
§ Blocks release of virus-filled droplets when you cough or sneeze.
facemasks
65
facemasks for COVID-19
N95 respirator mask
surgical masks
66
filters out 95% of the smallest particles in air
(size of 0.1 to 0.3 um)
n95 respirator masks
67
shield large droplets from sick person
surgical masks
68
used in
modern microbiology
laboratories.
membrane filter
69
made from polymers of
cellulose acetate, cellulose
nitrate, polycarbonate,
polyester, polypropylene or
polysulfone.
membrane filter
70
size of membrane filters
§ 0.01µm, 0.22µm, 0.45µm
71
size of high efficiency particulate air filter
0.3 um
72
what BSL is required for processing COVID-19 related samples
BSL-3
73
laboratory in DLSUD is what biosafety level
BSL-2
74
BSL level not known to consistently cause disease in healthy adult humans and of minimal potential hazards to laboratory personnel and environment
Ex. S. cerevisiae, E.coli, non-infectious bacteria
BSL-1
75
BSL level that has moderate potential hazard to personnel and the environment. Includes bacteria that cause mild disease to humans, and are difficult to contract via aerosol in a lab setting
BSL-2
76
BSL level where microbes can either be indigenous or exotic, and they can cause serious or potentially lethal disease through respiratory transmission
BSL-3
77
BSL level that is dangerous, exotic, and posing a high risk of aerosol-transmitted infections, infections caused by these microbes are frequently fatal and without treatment or vaccines
BSL-4
78
BSL level that work on open bench, lab coat and gloves recommended, and decontamination procedures are in place
BSL-1
79
BSL level that is used to work with biological agents or materials with moderate risk to the people and environment
aerosol-generating procedures are performed in a biosafety cabinet
lab coat and gloves is required
biosafety manual with lab-sepcific procedures/training and restricted access
BSL-2
80
BSL level that has lab designed to contain airborne hazard (double door entry, negative airflow to surrounding areas, no recirculation of air)
respiratory protections usually required
BSL-3
81
HEPA meaning
high efficiency particulate air filter
82
Water can be removed from foods by
heating
evaporation
freeze-drying
addition of salt or sugar
83
methods directly remove water from the sample
heating
evaporation
freeze-drying
84
chemical methods used to control microorganisms
antibiotics
antimicrobial agents
85
factors to consider in using chemical control agents
product specifications
surface topography
contact time
temperature/pH
86
is the most commonly used alcohol for control of microorganisms
ethanol
87
alcohol concentration Between _____ are effective against vegetative cells
50-90%
88
alcohol concentration that is used for
practical purposes
70%
89
alcohol concentration Above ___% is effective in killing viruses.
60%
90
§ Used as sanitizer/antiseptic on skin at 40%
alcohol
91
alcohol is used as a sanitizer/antiseptic on skin at ____%
40%
92
Used as sanitizer/antiseptic on skin at 40%, disinfectant to clinical instruments,
thermometers and surgical instruments.
alcohol
93
alcohol solubilizes ___ bilayer of cell walls and membrane and create pores.
lipid
94
alcohol § ____ dproteins in the cytoplasm
denature
95
alcohol § ____ cells at very high concentration.
dehydrates
96
found in wax (lignin)
phenol and phenolic compounds
97
Has wide spectrum of antimicrobial action.
§ Kills vegetative cells by concentrated aqueous solution, bacterial
spores are resistant.
phenol and phenolic compounds
98
___ aqueous solution of phenol is used as disinfectant
2-4%
99
derivatives of phenol and phenolic compounds
cresol
chloroxylenol
chlorohexidane
hexaclorophene
100
phenol compound in lysol
cresol
101
phenol compound used as antiseptic
chloroxylenol
102
phenol compound as an active ingeredient of Dettol
chloroxylenol
103
phenolic compound used in antiseptics
chlorohexidane
104
phenolic compound used in soap
hexachlorophrene
105
mode of action of phenol and phenolic compounds
___of cell, ____of cell proteins, ___of
enzymes and ___of materials.
disruption
precipitation
ianctivation
leakage
106
– used in aqueous solution, tincture of iodine and
iodophore (more used).
iodine
107
Effective against all kinds of bacteria; possess sporicidal activity
halogen compounds
108
§ Fungicidal and to some extent virucidal.
halogen compounds
109
§ Widely used as antisepsis of skin, mucus membrane and wound.
halogen compound
110
Used also as disinfection of air, water and sanitation of food
utensils.
halogen compound
111
mode of action of halogen compounds
§ ___agents in cellular materials.
§ Halogenation of proteins resulting in ___.
oxidizing
inactivation
112
– in form of hypochlorite and chloramine as disinfectan
chlorine
113
solid chlorine disinfectant
calcium hypochlorite
114
liquid chlorine disinfectant
sodium hypochlorite
115
Aqueous solution of sodium hypochlorite at 5-25% is called
house hold bleach
116
is more stable than hypochlorites
chloramine
117
is common water disinfectant
chlorine
118
chlorine ratio for either in clinical and lab setting
1:10
119
chlorine ratio in general cleaning and household.
1:100
120
what chlorine is sanitizer for cooking utensils
Calcium hypochlorite
121
is used in bathing water
what chlorine compound
1% bleach
122
chlorine percentage is used in swimming pool and household purposes.
5-12%
123
is chlorine used as antiseptic?
no
124
mode of action of chlorine
§ When active form is added in water, free chlorine releases
____ ____(HClO)
hypochlorous acid
125
decompose to release nascent oxygen which is
a powerful oxidizing agent in cellular components.
hypocholorous acid
126
Hypochlorous acid decompose to release ___ ____which is
a powerful oxidizing agent in cellular components
nascent oxygen
127
Hypochlorous acid decompose to release nascent oxygen which is
a powerful ___agent in cellular components.
oxidizing
128
agent that will take electrons from DNA or enzymes
oxiziding acid
129
§ Most ___ metals have antimicrobial action.
heavy
130
heavy metals with antimicrobial action
mercury
silver
copper
131
mode of action of heavy metals
§ Combines with cellular ____ and ____ and inactivates them.
proteins
enzymes
132
heavy metal mode of action
High concentration also ____ and ___cellular proteins
and kills microbes.
coagulates
precipitates
133
§ Commonly used metal compounds in antiseptics
HgCl HgCl2
134
§ Commonly used metal compound that is bacteriostatic and bacterocidal
AgNO3
135
found in eyedrops used in newborn to prevent ophthalmia neonatorum
silver nitrate
136
§ Commonly used metal compounds used against algae and mold in pools
copper sulfate
137
is a bacterial or viral eye infection that can occur in newborns during the first month of life:
ophtalmia neonatorum
138
Formaldehyde and glutaraldehyde are examples. Both are microbicidal and
sporicidal.
aldehydes
139
* Stable in higher concentration and higher temp. i.e at room temp.,
formaldehyde
140
in room temp, aldehyde forms
para-formaldehyde
141
Can be gaseous or in formalin (40% solution of formaldehyde)
formaldehyde
142
40% solution of formaldehyde
formalin
143
are used for disinfectiona and sterilization of closed
room such as operation theater
vapour or formalin
144
r is used as disinfectant of woolen blanket, wools and
footwares of fungal infected persons.
formladehyde vapor
145
is used in preservation of biological specimen
formalin
146
Used in 2% solution
§ Effective against bacteria, fungi, spores and viruses.
§ Used to sterilize urological specimen and respiratory therapy
instruments.
glutaraldehyde
147
gaseous agents include
ethylene oxide
b-propiolacetone
formaldehyde
148
* Gaseous above 10.8C
* Have high antimicrobial activity and kill endospores.
* Used in sterilization of heat sensitive materials such as spices, oils, plastics
etc.
ethylene oxide
149
* Used with CO2 to form Freon.
ethylene oxide
150
ethylene oxide is * Used with CO2 to form ___.
freon
151
Gas above 15.5 C
* Less penetration power than ethylene but more active in killing
microorganisms.
b-propiolacetone
152
Carcinogenic, hence, less used.
b-propiolactone
153
* Primarily used in cleaning but has antimicrobial prop.
surfactants
154
surfactants means
surface-active agents
155
three types of surfactants
cationic
anionic
non-ionic
156
has more significant germicidal than the two other surfactants
cationic
157
cationic and is germicidal to gram pos
quaternary ammonium
158
Also used as disinfectants, sanitizers and antiseptics. i.e. to
floors
surfactants
159
surfactants Kills microorganisms by denaturing ___and interfere with
___.
proteins
glycolysis
160
surfactants damages ___ and ___
cell wall
cell membrane
161
Degerming
i.e. breaks oily
droplets by
emulsification
soap
162
Sanitizing (neg
charged
surfactants
reacting with cell
membranes
acid-anionic detergents
163
Bactericidal,
Denature
proteins, disrupt
plasma
membrane (more
active against g+
quaternary ammonium compounds
cationic detergents
164
§ Produces hydroxyl free radicals
§ Effective at 6% to 25% solution
§ Used as antiseptics
hydrogen peroxide
165
hydrogen peroxide ___ solution is used for vaporous treatment
30%
166
These are secondary
metabolites of some
microorganisms which inhibits
growth of microorganisms
antibiotics
167
Inhibits cell wall peptidoglycan
synthesis
penicillin
168
* Inhibits cell membrane
biosynthesis:
polymyxin
169
Inhibits protein synthesis:
chloramphenicol
chloramphenicol
170
* Reacts with nucleic acids
rifampin
171
* Inhibits folic acid synthesis:
sulfonamide
172
antibiotic that affect cell wall synthesis
beta lactams
penicillin
cephalosporin
carbapenems
monobactams
vancomycin
bacitracin
173
antibiotics that affect cell membrane
polymyxin
174
antibiotics that affect 30s subunit
tetracycline
aminoglycosides
175
antibiotics that affect 50s subunit
macrolides
clindamycin
linezolid
chloramphenicol
streptogramins
176
Denatures proteins and
solubilizes lipids
Antiseptic used on skin
ethanol, isopropanol
177
Denature proteins and
disrupt cell membranes
Antiseptics at low
concentrations;
phenolic compounds
178
Inactivates proteins
Antiseptic used on skin
tincture of iodine
179
Forms hypochlorous acid
(HClO), a strong oxidizing
agent
Disinfect drinking water; general
disinfectant
chlorine gas
180
Precipitates proteins General antiseptic and formally
used in the eyes of newborns.
Erythromycin drops (an
antibiotic) are now used
silver nitrate
181
Inactivates proteins by
reacting with sulfide groups
Disinfectant, although
occasionally used as an
antiseptic on skin
mercuric chloride
182
Reacts with NH2, SH and
COOH groups
Disinfectant, kills endospores
(sterilant)
formaldehyde
183
Alkylating agent Disinfectant used to sterilize
heat-sensitive objects such as
rubber and plastics
ethylene oxide gas
184
Disrupts cell membranes At higher concentrations and
with some compounds is a
disinfectant
detergents
