Exam 3: Ch 9 Flashcards
Destruction of pathogenic organisms on inanimate objects; may not destroy endospores.
Disinfection
The destruction of pathogenic organisms on living organisms
Antisepsis
Physical removal of microorganisms from surfaces, like washing hands and taking a bath
Degerming
Reduction of microbes to a level deemed safe by public health guidelines as in restaurants
Sanitization
The destruction of all forms of life including endospores (strictly speaking not possible because prions are tough to destroy)
Sterilization
Bacterial contamination
Presence of bacteria in blood
Presence of actively reproducing bacteria in blood
Sepsis
Bacteremia
Septicemia
- cide suffix
- static or -stasis
To kill, biocides, germicide, fungicide, etc
Inhibit the growth and reproduction of; fungistasis, bacteriostatic
Factors affecting this rate are: number of microbes, environment, time, type of microbe
Rate of microbial death
Lowest temperature that will kill all cells in a liquid in 10 minutes
Thermal death point (TDP)
Physical Method
The minimum time for all bacteria to be killed in a particular volume of liquid at a set temperature
Thermal death time (TDT)
Physical Method
The time, in minutes, in which 90% of the bacteria will be killed
Decimal reduction time (DRT)
Physical Method
Common household items like baby bottles have this done at 100C for 10 minutes. Kills most pathogens. Hep B requires 2 hours.
Boiling
Moist heat
Protein denaturation
Dishes, etc
Steam under pressure at 121C, 15 psi, 15 minutes destroys all microbes including endospores, except prions
Autoclave
Moist heat
Protein denaturation
Medical uses
Low temperature treatment of dairy, wine, and beer at 63C for 30 minutes (classical method)
Pasteurization
Moist heat
Protein denaturation
High temperature short time (HTST) pasteurization
72C for 15 seconds
Beverages
Ultra-high temperature pasteurization (UHT)
140C for less than 1 second, maybe 3
Flaming, incineration, hot-oven sterilization at 170C for 2 hours.
Dry heat or hot air sterilization?
Burning to ashes
Oxidation
Instruments, glassware, needles, loops
Cause of death used for liquids sensitive to heat (serum and antiseria)
Membrane filter with pore sizes 22-44 um retain bacteria
HEPA (high efficiency particulate air) filter used in vents, operating rooms, and wards for immune compromised and burn patients
Causes bacteriostatic effect except in the care if psychrotrophs, which will alter the appearance and taste of food with time
Refrigeration (0-8C)
Food-borne pathogen L. monocytogenes, turkey cold cuts
Causes organisms to become dormant. The trichinosis roundworm is killed with several days of this method.
Freezing
Freeze-drying (shell freezing using chilled acetone). Water removed by high vacuum at low temperature.
Lyophilization
Causes the disruption and cessation of metabolism (eg drying of meat and fruit practiced for hundred of years)
Certain microbes and endospores remain viable and are important in hospital settings
Dessication
The use of high concentrates of salts and sugars creates a hypertonic environment and caused water to leave the cell- plasmolysis.
Fungi tolerate this better than bacteria, like growth of molds on jams.
Osmotic pressure
Destruction of DNA, gamma rays, X rays, or high energy electron beams. Marked with irradiation (Radora) logo
Ionizing radiation
Wavelength shorter than 1 mm
Used by USPS to sterilize mail after 9/11, sterilizing medical supplies and more recently for food preservation.
