Test 3 Chapter 13 Study Guide Flashcards
Biosafety Level 1 (BSL-1)
Handling Pathogens that do not cause disease in healthy humans
Biosafety Level 2 (BSL-2)
Handling Moderatly Hazardous agents.
Biosafety Level 3 (BSL-3)
Handling microbes in safety cabinets. Double Door system, negative pressure
Biosafety Level 4 (BSL-4)
Handling microbes that cause sever or fatal disease
Sterilization
Complete 100% removal of vegetative cells, endospores, and viruses
Aseptic Technique
Prevents contamination of sterile surfaces
Commerical Sterilization for food
Not truly sterile because many non-pathogenetic organisms survive. Goal is to get rid of pathogens.
Disinfection
removes MOST microbes from the SURFACE OF AN OBJECT
Antiseptics
Removes MOST microbes from LIVING Tissue
Degerming
SCRUBBING of LIVING TISSUE with a mild chemical (handwashing)
Sanitization
cleansing of fomites enough to achieve levels deemed safe for public health
Bacteriocides
Kills bacteria
Bacteriostatic
Doesn’t kill bacteria just stops growth
Fungicides
Kills fungi
Fungistatic
Doesn’t kill fungi, just stops growth
Viricidal
Makes viruses non-infectious
D-Value
Amount to kill 90% of the population. Regardless of size of the population.
Effects of High Temperatures on Bacterial Growth
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. Does not include endospores
Thermal Death Time
Time to sterilize volume of liquid at set temperature. Does include endospores
3 microorganisms that can survive boiling
Endospores, Protozoan cysts, some viruses(?)
Boiling time and sterilization
Boiling time is critical for proper sterilization. Higher elevation requires longer boiling time.
Boiling Time can’t kill
No matter how long you boil you wont kill endospores or protozoan cysts
Autoclaving
combination of moist heat and pressure
Autoclaving Process
Pressure is applied to boiling water. This prevents steam from escaping. Boiling temperature increases as pressures increase
Autoclave Conditions
121oC, 15 psi, 15 minutes
Pasteurization Isn’t sterilization
Pasteurization is not sterilization because heat-tolerant microbes will survive
Flash Pasteurization
Most common, High temperature short time, Not sterilization, just pathogens
Ultrahigh-Temperature pasteurization
Sterilization. Coffee creamer. Boxed milk.
Cold environments and microbes
decrease microbial metabolism, growth, and reproduction. Refrigeration halts growth of most pathogens.
slow freezing vs rapid freezing
Slow freeze allows ice crystals to form in the bacterial cell. Quick freeze might put the microbes in a vegetative state.
Lyophilization (freeze-drying)
used for long-term preservation of microbial cultures. Prevents formation of the ice crystals in slow freezing that would damage the cells.
Desiccation (drying)
inhibits growth due to the removal of water.
Osmotic Pressure
High concentrations of slat or sugar in foods to inhibit growth.
Cells in hypertonic solution of salt or sugar
Lose water
Ionizing radiation
ejects electrons from atoms to create ions
Ionizing radiation on Microbes
Ions disrupt hydrogen bonding, oxidize double covalent bonds, and create hydroxyl radicals. Gamma rays penetrate well but require hours to kill microbes. X-rays require long time to kill microbes. Not practical microbe control
Joseph Lister
first to use antiseptic to help prevent surgical and post-surgical infections
Phenolics Affect
Denatures proteins, disrupt membrane, Effective in presence of organic matter
Phenolics Examples
Listerine, Lysol, Triclosan
Heavy Metals Affect
Binds to proteins and inhibit enzymatic activity. Not selective to microbes
Heavy Metals Examples
Mercury, Silver, Copper, Nickle, and Zinc
Halogens Affect
Oxidation and destabilization of macromolecules
Halogens Example
Iodine (betadine) chlorine, fluorine
Alcohols Affect
Denature proteins and disrupt cell membranes
Alcohols Acts as A
Bactericidal, Fungicidal, Viricidal for enveloped viruses only
Surfactants Affect
Lower surface tension of water - amphipathic. Can make lipids water soluble
Surfactants Examples
Soaps and detergents. Cationic Detergents. Quats
Bisbiguanides Affect
Cationic antiseptics, can be used on skin, disrupts cell membranes
Bisbiguanides Examples
Chlorhexidine
Alkylating Agents Affect
Inactivate enzymes and nucleic acids
Alkylating Agents Examples
Formaldehyde - Carcinogen. Ethylene Oxide - Sterilize surgical equipment that can’t be autoclaved
Oxidizing Agents Affect
Kill by oxidation of microbial enzymes. Peroxide, ozone, and peracetic acid.
Oxidizing Agents Example
High-level disinfectants and antiseptics.
Hydrogen peroxide
Can disinfect and sterilize surfaces. Not useful for treating open wounds due to catalase activity.
