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Microbiology > Chapter 9 Aseptic Technique > Flashcards

Chapter 9 Aseptic Technique Flashcards

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1
Q

Aseptic Technique

A

Is free of pathogens (contaminants)
Ex: Flame sterilization of laboratory equipment

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2
Q

Degerming

A

Removal of microbes by mechanical means
Ex:Handwashing or using alcohol wipes over a site

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3
Q

Disinfection

A

Destruction of most microorganisms and viruses on nonliving tissue
Ex: Alcohols and soaps used

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4
Q

Pasteurization

A

Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages
Ex: Pasteurized milk and juiced fruits

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5
Q

Sanitization

A

Removal of pathogens from objects to meet public health standards
Ex: Washing tableware in restaurants

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6
Q

Sterilization

A

Destruction of all microorganims and viruses in or on an object
Ex: Preparation of microbiological culture media incineration
140ºC for 1 to 3 seconds, then rapid cooling

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7
Q

Actions of antimicrobial agents

A
  • Alteration of cell walls and membranes
  • Cell wall maintains integrity of cell
  • Cells burst due to osmotic effects when damaged
  • Cytoplasmic membrane contains cytoplasm and controls passage of chemicals into and out of cell
  • Cellular contents leak out when damaged
  • Nonenveloped viruses have greater tolerance of harsh conditions
    Action of Antimicrobial Agents
  • Damage to proteins and nucleic acids
  • Protein function depends on 3-D shape
  • Extreme heat or certain chemicals denature proteins
  • Chemicals, radiation, and heat can alter or destroy nucleic acids
  • Produce fatal mutants
  • Halt protein synthesis through action on RNA
    Factors Affecting the Efficacy of Antimicrobial
    Methods
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8
Q

Most resistant organisms
Most susceptible organisms

A

Prions
Bacterial endospores
Mycobateria
Cysts of protozoa
Active-stage protozoa
Most Gram-negative bacteria
Fungi
Nondevelop viruses
Most Gram-positive bacteria
Envelop viruses

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9
Q

Germinicide classification

A

Low-level germicides
* Kill vegetative bacteria, fungi, protozoa, and some viruses
Intermediate-level germicides
* Kill fungal spores, protozoan cysts, viruses, and
pathogenic bacteria
High-level germicides
* Kill all pathogens, including endospores

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10
Q

Biosafety levels in the lab

A

Biosafety Level 1 (BSL-1)
* Handling pathogens that do not cause disease in healthy
humans
Biosafety Level 2 (BSL-2)
* Handling moderately hazardous agents
Biosafety Level 3 (BSL-3)
* Handling microbes in safety cabinets
Biosafety Level 4 (BSL-4)
* Handling microbes that cause severe or fatal disease

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11
Q

Heat-Related Methods

A
  • Denature proteins
  • Interfere with integrity of cytoplasmic membrane and cell wall
  • Disrupt structure and function of nucleic acids
  • Thermal death point
  • Lowest temperature that kills all cells in broth in 10 min
  • Thermal death time
  • Time to sterilize volume of liquid at set temperature
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12
Q

Moist heat methods

A
  • Used to disinfect, sanitize, sterilize, and pasteurize
  • Denatures proteins and destroys cytoplasmic membranes
  • More effective than dry heat
    Ex: * Boiling 212 degrees F
  • Autoclaving
  • Pasteurization
  • Ultrahigh-temperature sterilization 140ºC for 1 to 3 seconds, then rapid cooling
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13
Q

Autoclaving

A
  • Pressure applied to boiling water prevents steam from escaping
  • Boiling temperature increases as pressure increases
  • Autoclave conditions: 121ºC, 15 psi, 15 minutes
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14
Q

Desiccation and Lyophilization

A

→ * Desiccation (drying) inhibits growth due to the removal of water
→ * Lyophilization (freeze-drying) used for long-term
preservation of microbial cultures

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15
Q

Osmotic Pressure

A
  • High concentrations of salt or sugar in foods to inhibit
    growth
  • Cells in hypertonic solution of salt or sugar lose water
  • Fungi have greater ability than bacteria to survive hypertonic environments
    Radiation
    Ionizing radiation
  • Wavelengths shorter than 1 nm
  • Electron beams, gamma ray, some X rays
  • Ejects electrons from atoms to create ions
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16
Q

Chemical Methods of Microbial Control

A

Phenol and Phenolics
* Denature proteins and disrupt cell membranes
* Effective in presence of organic matter
* Remain active for prolonged time
Alcohols
Intermediate-level disinfectant
* More effective than soap in removing bacteria from hands
* Swabbing of skin with alcohol prior to injection removes
most microbes
Halogens
* Intermediate-level antimicrobial chemicals
* Damage enzymes by denaturation
* Widely used in numerous applications
* Iodine tablets, iodophores, chlorine treatment, bleach,
chloramines, and bromine disinfection
Oxidizing Agents (anaerobic infections fast used)
* Peroxides, ozone, and peracetic acid
* Kill by oxidation of microbial enzymes
* High-level disinfectants and antiseptics
* Hydrogen peroxide can disinfect and sterilize surfaces
* Not useful for treating open wounds due to catalase activity
Surfactants
* “Surface active” chemicals
Soaps and detergents
* Soaps have hydrophilic and hydrophobic ends
* Good degerming agents but not antimicrobial
Quats
* Low-level disinfectants
* Disrupt cellular membranes
* Ideal for many medical and industrial applications
Heavy Metals
* Heavy-metal ions denature proteins
* Low-level bacteriostatic and fungistatic agents
* 1% silver nitrate to prevent blindness caused by N. gonorrhoeae
Aldehydes (good at preventing micro bacterial growth)
* Compounds containing terminal –CHO groups
* 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.
Gaseous Agents (they can be hazardous to use)
* Microbicidal and sporicidal gases used in closed chambers to
sterilize items
* Denature proteins and DNA by cross-linking functional groups
* Used in hospitals and dental offices
* Disadvantages
* Can be hazardous to people
* Often highly explosive
* Extremely poisonous
* Potentially carcinogenic

17
Q

Enzymes

A
  • Antimicrobial enzymes act against microorganisms
  • Human tears contain lysozyme
  • Digests peptidoglycan cell wall of bacteria
  • Use enzymes to control microbes in the environment
    -Lysozyme used to reduce the number of bacteria in cheese
    -Prionzyme can remove prions on medical instruments
18
Q

Antibiotics

A

(coming from a living organism are going to be use for treatment of disease) and semisynthetic and synthetic chemicals
Typically used for treatment of disease
* Some used for antimicrobial control outside the body

19
Q

Dilution test evaluating disinfectants and antiseptics

A
  • Metal cylinders dipped into broth cultures of bacteria
  • 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

Microbiology (4 decks)

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