Exam #2 Lecture Flashcards
Sterilization
The process by which ALL living cells, spores, and viruses are destroyed on an object.
Distinfection
Killing or removal, of a disease-producing organisms from INANIMATE SURFACES.
Antisepsis
Killing or removal, of a disease-producing organisms from the surface of LIVING TISSUE
Sanitation/Decontamination
Mechanically removal of microorganism
- Filtration
- Air(decontamination)
- Liquids(Sterilization)
Chemical Agents
Gases and liquids
Gases
Sterilization and disinfection
Liquids
- On animate objects- Antisepsis
* On inanimate objects- Disinfection & Sterilization
Physical agents
Heat and Radiation
Heat
- Dry
- Incineration(Sterilization)
- Dry Oven (Sterilization)
- Moist
- Steam under pressure (Sterilization)
- Boiling water, hot water, pasteurization (Disinfection)
Radiation
- Ionizing
- X ray, cathode, gamma (Sterilization)
*Nonionizing
UV (Disinfection)
What is the most resistant microbial entities?
Bacterial endospores
What is the goal of sterilization?
To destroy the Bacterial Endospores, so that it can kill any less resistant microbial forms.
List most resistant to less resistant microbes:
- Prions
- Bacterial endospores
- Mycobacterium
- Staphylococcus and Pseudomonas
- Protozoan trophozoites
- Most gram-negative bacteria
- Fungi and fungal spore
- No enveloped viruses
- Most gram-positive bacteria
- Enveloped viruses
Least Selective agents
Tend to be effective against the widest range of microbes (heat and radiation)
Selective agents
Target only a singular cellular component (drugs)
Cellular target of physical and chemical agents?
- Cell wall
- Cell membrane
- Cellular synthetic processes
- Proteins
Cell wall effects of agents
Chemical agents can damage the cell wall by;
- blocking its synthesis
- digesting the cell wall
Cell wall examples of agents
- Chemicals
- Detergents
- Alcohol
Cytoplasmic membrane effects of agents
Agents physically bind to lipid layer, open it up and allow injurious chemicals enter and important ions to exit the cell
Cytoplasmic membrane examples of agents used
-Detergents
Cellular synthesis effects of agents
Agents can interrupt the synthesis of proteins via ribosomes:
- inhibiting proteins growth
- metabolism
- preventing multiplication.
Cellular synthesis examples of agents used
- Formaldehyde
- Radiation
- Ethylene oxide
Proteins effects of agents
- Agents can denature proteins (breaking protein bonds)
- Agents may attach to the active site of protein, so it can not interact with chemical substrate
Moist heat temp and time to sterilize
121 degrees —-> 15min
125 degrees —-> 10min
134 degrees —-> 3 min
Dry Heat temp to time sterilized
121 degrees —-> 600 min
140 degrees —-> 180 min
160 degrees —-> 120 min
170 degrees —-> 60 min
The cold treatment
Slows growth of cultures and microbes in food during processing and storage, it retards the activities
Things that don’t adversely addictive microbes?
- Gradual cooling
- Long-term refrigeration
- deep-freezing
What temperature preserves cultures of bacteria, viruses, and fungi for long periods of time?
(-70) degrees C to (-135) degrees C
Desiccation
- Vegetative cells directly exposed to normal room temp gradually become dehydrated
- Some are killed and others no effect
Lyophilization
- A combo of freezing and drying
- Method to preserve microbes
*Pure cultures frozen instantaneously exposed to vacuum that removes water avoiding ice crystals
Radiation
Energy emitted from atomic activities and dispersed at high velocity through matter or space
Increasing energy to low energy
- Gamma rays
- X-rays
- Ultraviolet radiation
What is the wave length in Ionizing radiation?
-Wave length shorter than 1nm- electron beans gamma rays and X rays
What does ionizing radiation do?
-It creates ions by ejecting electrons from atoms they strike
- Ions disrupt
- hydrogen bonding
- Oxidize double covalent bonds
*Ions create
Hydroxide ions, that denature other molecules (DNA)
Ionizing radiation- Electron beams
*Effective kill, but has bad penetration Uses: -Sterilize sliced meats -microbiological plastic ware -medical/dental supplies
Ionizing radiation- Gamma rays
*Penetrate well, but needs hours to kill microbes Uses: *Sterilize -meats -Spices -Fresh fruits -Veggies
Ionizing radiation- X-rays
Requires to much time to be practical for growth control
What is the length of Non-ionizing radiation?
Wavelength greater than 1nm
What does non-ionizing radiation do?
- Excites electrons and causes them to make new covalent bonds.
- affects the 3-D structures in proteins & nucleic acids
What are some examples of non-ionizing radiations?
- UV light causes thymine dimmers in DNA
- UV light does not penetrate well
- Suitable for disinfecting
- air
- transparent fluids
- surfaces of objects
Filtration
An effective method to remove microbes from air and liquids
Examples of filtration?
- Fluid strained through filter with openings for fluid to pass, but not microbes
- Pore sizes can be controlled to permit true sterilization by trapping viruses or large proteins
How is filtration used?
- To prepare liquids that cant withstand heat:
- serums
- blood products
- vaccines
- drugs
- IV fluids
- enzymes
- media
- A good alternative method:
- decontaminating milk to keep its flavor
- important for water purification
*can not remove toxins
Osmotic pressure
Adding large amounts of salt or sugar to foods creates a hypertonic environment for bacteria, causing plasmolysis
Examples of Osmotic pressure?
- Pickling
- Smoking
- Drying foods
*Is never a sterilizing technique
What are the chemical agents in microbial control?
- Occur
- Liquid
- Gaseous
- Solid states
- Range from:
- Disinfectants
- Antiseptics
- Sterilants
- preservatives
Selecting a microbicidal chemical
- Rapid action- even low concentrations
- Solubility/long term stability- in water or alcohol
- Broad spectrum- without being toxic to human and animal tissue
- Penetration- of inanimate surfaces to sustain a cumulative action
- Resistance- to become inactivated by organic matter
Selecting a microbicidal chemical (continued)
- Noncorrosive or nonstaining
- Sanitizing and deodorizing
- Affordability and ready availability
- No chemical can fulfill all of these requirements
- Glutaraldehyde and hydrogen peroxide are close
How are germicides evaluated?
By their effectiveness in destroying microbes in medical and dental settings
What are the high, intermediate, and low levels of germicides?
- High level germicides- Kill endospores and can be used as sterilants
- Intermediate level germicides- Kill fungal, but not bacterial spores, resist pathogens, and viruses
- Low level germicides- Eliminate only vegetative bacteria, vegetative fungal cells, and some viruses
Factors affecting the germicidal activities of chemicals?
- Nature of microorganisms be treated
- Nature of material being treated
- Degree of contamination
- TIme of exposure
- Strength and chemical
Composition of material being treated?
- Smooth, solid objects are more likely disinfected than those with pores or pockets
- Large amounts of organic material can hinder penetration
- Adequate cleaning instruments and reusable materials my continue use of a germicide or sterilant.
Phenol
Denatures protein
Iodine
Membrane damage
Chlorhexidine
Membrane disruption and protein desaturation
Alcohols
Protein denaturation, dissolve membrane lipids
Hydrogen peroxide
Hydroxyl radicals attack membrane lipids, DNA, protein
Antimicrobial agents- Dyes
- Active against gram positive bacteria and fungi
- Limited application because they stain and have a narrow spectrum of activity
Antimicrobial agents- acids and alkalis
- Very low or ugh pH can destroy or inhibit microbial cells
- Limited in applications due to corrosive, caustic, hazardous nature
- Ammonium hydroxide used in detergents, cleaners, deodorizer
- Organic acids used in food preservation
Gaseous agents
-Ethylene oxide
-Propylene oxide
Used in closed chambers to sterilize items
*Denature proteins and DNA by cross-linking functional groups
Where are gaseous agents?
-Used in hospitals and dental offices
- Can be:
- hazardous to people
- Often highly explosive
- extremely poisonous
- Potentially carcinogenic
