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Microbiology > Chapter 7: Microbial Growth and Decontamination > Flashcards

Chapter 7: Microbial Growth and Decontamination Flashcards

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1
Q

Microbial Growth

A

is cell division that produces new (daughter) cells and increase the total cell population

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2
Q

In healthcare settings, biofilms are a major concern because…

A

they are difficult to treat and can contribute to persistent infections

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3
Q

Binary Fission

A

occurs in most prokarotes; onvolves dividing a single cell into two cells; asexual; before dividing chromosomes replicate; parent cell begins to pinch off; partition (septum) in the center becomes complete; creates two genetically identical daughter cells

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4
Q

Budding

A

asexual reproduction; original cell eleongates then decelops a small outgrowth on one side; chromosome is duplicated and placed in the bud; separation from the mother cell occurs; performed by certain fungi and some bacteria (hyphomicrobium)

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5
Q

Spore Formation

A

performed by some fungi and bacteria; can be sexual or asexual in fungi; ALWAYS asexual in bacteria; Formation Varies- streptomyces form spores that hang off of long hypahe extensions

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6
Q

Generation Time

A

time it takes for a cell to divide; times vary; can range from 15 mins to 24 hours; depends on species and conditions; avaible nutrients impacts time; many common bacteria is less than an hour (E. coli) and some have slow (Mycobacterium tuberculosis 15-20hrs)

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7
Q

Binary fission leads to what type of growth?

A

exponential

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8
Q

Closed Pure Batch Cultures

A

means that nothing goes in and nothing goes out; the nutrients and cells that are put in are what stay in there; wastes are not removed; allows growth phases to be observed

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9
Q

Lag Phase

A

phase 1; delay that occurs while cells adjust to their new environment

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10
Q

Log Phase

A

phase 2; period of rapid exponential growth

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11
Q

Stationary Phase

A

phase 3; nutrients are depleted (but not gone) and waste accumulates; population growth rate levels off; basically growth rate is equal to death rate

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12
Q

Death Phase

A

phase 4; critical point of waste buildup and decreasing nutrients; cells begin to die; exponential death rate; **small number of the cells survive by adapting to the waste and by feeding off dead cells

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13
Q

Chemostat

A

open system; fresh growth medium is added; waste and excess cells are removed; constantly keeps them in log phase; common in industry

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14
Q

Temperature

A

low- decreases enzymatic rxns; increased- speeds up rxns and can increase growth rate; high-denature proteins and kills cell

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15
Q

Barophiles

A

can withstand the high pressure envirnoment of the deep sea

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16
Q

Psychrophiles

A

thrive between -20 and 10 degree C

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17
Q

Psychotrophs

A

grow at about 0-30 C; associated with foodborne illness

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18
Q

Mesophiles

A

grow best around 10-50 C; associated with most pathogens

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19
Q

Thermophiles

A

grow around 40-75 C; associated with compost piles and hot springs

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20
Q

Extreme Thermophiles

A

grow around 65-120 C (sterilization is 121)

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21
Q

Acidophiles

A

grow at pH 1 to pH 5; live in areas such as sulfur hot springs and volcanic vents; oftain maintain a fairly neutral cytoplasmic pH; proton pumps export excess protons from the cytoplasm to raise pH

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22
Q

Neutralophiles

A

grow best in a pH range of 5-8; make up the majority of microorganisms (human pH is about 7)

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23
Q

Alkaliphiles

A

grow in pH range of 9-11; associated with soda lakes

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24
Q

Halophiles

A

thrive in high salt environments; tolerate up to 35%; associated with the dead sea and the Great Salt Lake of Utah; normal cells would undergo plasmolysis but halophiles keep high concentrations of organic material and ions in their cytoplasm (to balance the graidents)

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25
Q

Faculative Halophiles

A

tolerate higher salt but may not grow well; ex) staphylococcus aureaus

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26
Q

Oxygen Levels

A

many microbes on this planet live either without oxygen or minimal; oxygens levels are low beneath the soil or within silt deposits in lakes and oceans; most pathogens thrive in low oxygne environemnt within the host

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27
Q

Reactive Oxygen Species

A

what some oxygen is converted into; such as superoxide ions and hydrogen peroxide; ROS can rapidly damage proteins and DNA; many microbes have evolved ways to detoxify ROS

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28
Q

Many Aerobe microbes rely on antioxidants to detoxify ROS…

A

antioxidants are compounds and enzymes; ex) superoxide dismutase converts reactive superoxide ions to hydrogen peroxide , catalse converts hydrogen peroxide to water and oxygen

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29
Q

Obligate Aerobes

A

absolute dependence on o2 for cellular processes

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30
Q

Microaerophiels

A

use only small amounts of o2; live in low o2 settings

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31
Q

Facultative Anaerobes

A

grow with and without o2; swtich between using o2 and fermentation

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32
Q

Anaerobes

A

do not use o2 in their metabolic processes

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33
Q

Aerotolerant Anaerobes

A

tolerate o2 but do not use it in their metabolic processes; have ways to deactivate ROS

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34
Q

Obligate Anaerobes

A

do not use o2 in their metabolism; can not eliminate ROS; tend to die in aerobic environments

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35
Q

What is 90% of a cells dry weight?

A

carbon, hydrogen, nongaseous oxygen, and nitrogen; other important elematents are sulfur, phosphorus, potassium, sodium, calcium, magnesium and chlorine and carious metal ions

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36
Q

Essential Nutrients

A

required to build new cells; found in the organic and inorganic compounds of a microbes environment

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37
Q

Macronutrients

A

needed in large amounts; such as carbon

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38
Q

Micronutrients

A

needed in very small amounts such as iron

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39
Q

Heterotrophs

A

require an external source of organic carbon (sugars, lipids, proteins)

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40
Q

Autotrophs

A

do not require ane xternal source of organic carbon; use carbon fixation to convert inorganic carbon into organic carbon

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41
Q

Growth Factors

A

necessary substances that a cell can not make on its own; cell must import them from their environment; they can not build their own

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42
Q

Fastidious Organisms

A

are organisms that need multiple growth factors; amino acids, vitamins, nitrogenous bases etc must be supplied in the growth media

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43
Q

Phototrophs

A

organisms that use light energy

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44
Q

Chemotrophs

A

are organisms that break down chemical compounds for energy

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45
Q

Photoautotroph

A

energy source of sunlight; inorganic carbon source (Co2); ex is cyanobacteria found in fresh water environments

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46
Q

Photoheterotrophs

A

energy source of sunglight;; organic carbon source; ex is heliobacillus mobilis foud in rice paddy fields

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47
Q

Chemoautotroph

A

energy source of nutrient breakdown; inorganic carbon source (usually co2); ex) thiobacillus dentirificans found in soil, mud and freshwater and marine sediments

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48
Q

Chemoheterotrophs

A

nutrient breakdown energy source; organic carbon source; ex is E. coli a common inhabitant of mammalian inestines

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49
Q

LIquid Media

A

ideal for growing large abtches of microbes

50
Q

Solid Media

A

useful for isolating colonies and observing specific culture characteristics

51
Q

Semisolid Media

A

useful for motility testing

52
Q

Broth Media

A

made by dding various nutrients to purified water; poured into flasks or tubes and sterilized

53
Q

Solid and Semisolid Media in Petri Plates

A

made by adding a powdered polysaccharide called agar to liquid media (add no nutrients); semi solid media contain less agar than solid media; medium is heat sterilized; while hot, the medium is poured into petri dishes; allowed to cool and solidy

54
Q

Slants

A

cool at an angle

55
Q

Deeps

A

cool upright

56
Q

Defined Media

A

aka syntheitc media; chemically defined or precisely known composition; each organic and inorganic component is completely known and quatified; useful for growing autotrophs and some heterotrophs

57
Q

Complex Media

A

aka enriched media; contains a mixture of organic and inorganic nutrients that are not fully defined; contain more complex ingredients (blood, milk proteins, extracts); precise quantity of every viteamen and nutrient si unknown; used to grow fastidious organisms with complex growth requirements

58
Q

Differential Media

A

media formulated to visually distinguish one microbe from anotehr; common example is blood agar; a microbe is not singled out

59
Q

Beta Hemolyitc

A

break down RBC

60
Q

Alpha Hemolytic

A

partial break down of RBC

61
Q

Gamma Hemolytic

A

do not lyse RBC

62
Q

Selective Media

A

single out bacteria that have specific properties; ingredients foster the growth of certain bacteria and suppress the growht of others; ex mannitol slat agar (MSA)

63
Q

Mannitol Salt Agar

A

selective due to its high salt content; differentiates organisms based on their ability to ferment a sugar called mannitol; it does this by the added pH indicator which detects the acids from fermentation

64
Q

Anaerobic Media

A

molecular o2 removed from media in a number of ways; such as thioglycate is added to media which is a reducing agent and converts o2 to water

65
Q

Anaerobic Jar

A

sample is added to chamber; packer of oxygen reating chemicals is opened inside it creating oxygen free conditions

66
Q

Anaerobic Chamber

A

large anaerobic box; gloves are inserted into the chamber to allow handling of organisms; samples are placed in a side compartment; nitrogen and/or co2 are piped into the chamber to displace all oxygen

67
Q

Streak Plate Technique

A

most commonly used technique to isolate bacteria; method dilutes a culture on a agar plate; individual cells are thinly separated from one another over the mediums surface; as cells divide their population increases to form a mound of cells called a colony

68
Q

Direct Methods

A

these methods involve counting individual cells or colonies (plate counts);

69
Q

Cell Counts

A

enumerates the number of cells in a small portion of the sample; can be done using automated or manual procedures

70
Q

Manual Cell Counting

A

requires a microscope and a specialized counting chamber that has a volumetric grid etched on it

71
Q

Flow Cytometer

A

direct method; uses a laser light to detect cells passing through a narrow channel; cells are fluorescently labeled before counting; ability to differentiate one cell type from another by using different colored labesl

72
Q

Viable Plate Count

A

direct method; allows for direct enumeration of bacteria using agar plates; samples are serially diluted; applied to agar using either spread plate method or pour plate method; after an incubation period, colonies are visible and can be counted; taking the dilution factor the number of living cells are calculated; numerical data for plate counts is usually represented as CFU per millilitere (or gram); reflectts thaat sometimes a clump of cells give rise to a colon

73
Q

Indirect Methods

A

rely on secondary reflections of overall population size

74
Q

Turbidity

A

fast and easy was to indirectly measure cells numbers; more cells = cloudier (more turbid); spectrophotometer measures either transmission or absorbance (optical density)

75
Q

Other Indirect Methods

A

assessing total dry weight; detecting levels of metabolic activity in a sample

76
Q

Physical Analysis

A

involves staining and microscopy to observe morphologial features

77
Q

Biochemical Analysis

A

involves a collection of media that assess metabolic properties

78
Q

Genetic Methods

A

also help to quickly identify microbes; probes polymerase chain reaction (PCR), DNA fingerprinting, electrophresis seapration methods

79
Q

Decontamination

A

removes or reduces microbial population to render an object safe for handling

80
Q

Sterilization

A

eliminates all bacteria, viruses and endospores; required for drugs, objects used for medicla procedures and for lab media and glass ware

81
Q

Disinfection

A

reduces microbial numbers; use for cosmetic, foods, surface, and exteral medical equipment

82
Q

Refrigeration/ Freezing

A

slow the growth of microbes; slows food spoilage, in the lab used to preserve specimen isolates and increase the shelf life of media; refrigeration preserves clinical samples

83
Q

Heat

A

most microbes are sensitive to heat; heat cna be used to acheive sterilization or decontamination

84
Q

Decimal Reduction Time

A

DRT or D value; time in minutes it takes to kill 90% of a given microbial population at a set temperature; associated with disinfection

85
Q

Thermal Death Time

A

shortest period of time at a certain temperature needed to kill all microbes in a sample

86
Q

Thermal Death Point

A

minimum temperature needed to kill all microbes in a sample with 10 minutes

87
Q

Autoclave

A

a machine that applies steam heat along with pressure to sterilize; used for microbiological media and assorted medical or lab equipment; most substances are sterile with 20 mins; pressure of 15 lbs per spuare inch and steam heat at 121 C

88
Q

Boiling

A

reduces microbial numbers; “boil water adivsory” given when drinking water is contaminated; boilinh water for 5 mins eleminates most pathogenic bacteria, protozoans, and viruses; endospores can withstand hours of boiling therefore it is not an efficeint sterilization method

89
Q

Pasteurization

A

used to eliminate pathogens; application of moderate heat (below the liquids boiling point); eliminates pathogens and reduces harmless micrbobes that cause milk spoilage

90
Q

Dr Heat

A

incineration or hot air ovens can also be used for steriliztion or disinfection; common examples of dry heat sterilization- heating an inoculating loop; ininerating waste; placing an object at 170 C for 2 hrs in a dry heat oven

91
Q

Radiation

A

some physical decontamination methods involve radiation or high energy waves; can sere as a disinfectant or steilization tool depending on the protocol; radiation is either ionizing or nonionizing

92
Q

Ionizing Radiation

A

gamma ray and x rays; generate reactive ions that kill microbes and inactivate viruses; damage nucleic acids

93
Q

Ionizing Radiation Passes through Packaging

A

useful in food and pharmaceutical industries; sterilizes medical supplies that cant be autoclaved

94
Q

Nonionizing Radiation

A

ultraviolet (UV) rays; causes thymine dimers; alter strucutre of DNA leading to mutation; uses UV light boxes in air handling systems, sanitize drinking water and swimming pools, disinfect surfaces in operating rooms, disinfect biosafety cabinet surfaces

95
Q

Filtration

A

large volumes of liquid or air can be passed through microbe capturing filters; filter pore sizes can even be made small enough to remove viruses; high efficiency particulate air (HEPA) filters remove microbes and allergens from the air

96
Q

HEPA Filters

A

made of randomly arranged fibers that remove 99.7% of airborne substances; pores are 0.3 micrometer or larger; does not sterilize air

97
Q

Process of Liquid Filtration

A

large volumes are pulled trhough the filter using a vacuum mechanism; smaller volues are pushed through syringes with filters attached to the end

98
Q

Microbiocidal

A

germicides that kill microbes

99
Q

Microbiostatic

A

germicides that only inhibit microbial growth

100
Q

Disinfectants

A

used to treat inanimate objects

101
Q

Antiseptics

A

applied to living tissue

102
Q

Low Level Agents

A

destroy bacteria (but not TB), fungi, and some viruses but not endospores

103
Q

Intermediate Level Agents

A

destroy all bacteria (including TB), fungi and viruses, but not endospores

104
Q

High Level Agents

A

destroy all microbes and endospores

105
Q

Critical Equipment

A

comes into contact with sterile body sites or the vascular system; must be sterilized

106
Q

Semicritical Equipment

A

comes in contact with mucous membranes or non intact skin; should be free of bacteria, fungi, and vrisues with low numbers of endospores

107
Q

Noncritical Equipment

A

contact pateints intact skin; require less stringent disinfection

108
Q

Alcohols

A

intermediate level disinfectants; denature proteins and attack lipid membranes; ex) ethanol and isopropanol; optimal concentration is 60-90%; used to disinfect small equipment (thermometers, scissors, stethoscopes)

109
Q

Aldehydes

A

high or intermediate level disinfectatns based on concentration; reacting with proteins and nucleic acid; ex) formaldehyde and glutaralhyde; used to sterilize. surgical instruments, endoscopes, dialyzers anestheria and respiratory equipement

110
Q

Phenols

A

intermediate level germicides; destroy bacterial cells walls and interact with proteins; ex) used in lysol; used in personal hygiene items (soap, mouthwash) as well as clinical

111
Q

Halogens

A

oxidize cell components; ex) chlorine and iodine compounds; chlroine bleach most widely used; used on medical equipement and floors and added to drinking water

112
Q

Perooxygens

A

highlevel germicides at high concentrations; can be used as antiseptics and disinfectants; strong oxidizing properties; ex) hydorgen peroxide, peracetic acid

113
Q

Ethylene Oxide

A

sterilant; damages proteins and nucleic acids; colorless gas; used for temperauter sensitive materials and equipement susceptible to moisture; applied to implant devices contain electronic parts or plastic components

114
Q

Detergents

A

cleaning agent; amphipathic molecules; remove water soluble and water insoluble substances; some detergents damage the lipid envelope of certain viruses and the lipid membrane of certain bacterial cells

115
Q

Anionic Detergents

A

have a negative charge and include soaps

116
Q

Cationic Detergents

A

have a positive charge and include quaternary ammonium compounds (QACs); have bactericidal activity and are sporostatic

117
Q

Facts Considered to select an Appropriate Germicide

A

item uses; germicide reactivity; germicide concentration and treatment times; types of infectious agents being controlled; presence of organic and inorganic matter; impact of germicicde residues on equipemnt use; germicide toxicity

118
Q

Mycobacterium Control

A

mycobacterium species cause tuberculosis and leprosy; contain cell walls rich in waxy mycolic acids; spreads by airborne droplets; control measures target reducing airborne particlaes from infected individuals

119
Q

Endospore COntrol

A

endospores are dormant structures; can revery to growing (vegetative) cells once favorable growth conditions are restored; endosproes survive drying, radiation, boiling, chemicals and heat treatments; most effective way to ensure elemination of endosproes is by autoclaving; other methods include hydrogen peroxide vapor at high heat or sporicides

120
Q

Viral Control

A

virsues can be resistant to some measures; lipids in the viral envelope are sensitive to heat, drying and detergents; naked viruses are usually inactivated by chlorine based agents

121
Q

Protozoan Control

A

different stages of a protozoan life cycle can resist certain control methods; ariety of treatments are used (filtration, carbon doxide, UV, and ozone treatments)

122
Q

Prion Control

A

infectious proteins; withstand autocalving and chemical sterilization; surgical devices are reused after autoclaving or chemical sterilization; prions are eliminated through a combination of chemical treatments and increased temp and pressure during autoclaving

Microbiology (9 decks)

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