lecture 10/27 for exam #4
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Created by:
kjordan9097 on November 4, 2011
Description:
PHYSICAL METHODS OF CONTROL
Classes:
Micro 102 Schimeld, Microbiology 102 CHC
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45 terms
Terms | Definitions |
|---|---|
 Physical methods of control | Heat Filtration Low temp Osmotic pressure Radiation Lyophilization |
| Physical method of control - Heat - 4 types | Moist heat Dry heat Pasteurization Ultra-high-temp processing |
| Moist Heat - 2 types | a. boiling 100 degree celcius - 10 minutes kills most bacteria b. autoclaving 100 degree celcius + 15psi --> 121 degree celcius for 15 minutes (1atmosphere) |
| Moist heat- a) boiling | boiling 100 degree celcius - 10 minutes kills most bacteria, vegatative cells, many fungi examples: hepatitis can survive 30 minutes of boiling, endospores 20 hours of boiling |
| Moist heat - b) autoclaving - | autoclaving 100 degree celcius + 15psi --> 121 degree celcius for 15 minutes (1atmosphere) |
| Dry Heat - 2 types | a. Direct flaming b. hot air sterilization |
| Dry heat - a) direct flaming | this is 100% effective even for endospores when you flame your loop - 100% effective, orange glow - but it is a limited application because you can't use heat on everything |
| Dry heat - b) hot air sterilization (in an oven) | 170 degree celicius - for two or more hours - 100% sterilization times depend on what you want to sterilize - small = 2 hours, bigger/denser = more than 2 hours |
| Pasteurization of milk - 2 types | a) classic pasteurization of milk - 63 degrees for 30 minutes (this is an old usage) b) modern pasteurization of milk - 72 degrees for 15 seconds (new usage) |
| Ultra-High-Temp used on processing the sterilization of milk - VHT | 140 degrees for 3 seconds - sterile production can be stored at room temperature for 6 months without opening - once opened shorter shelf life (ex: soy milk in a paper container) |
| Physical method of control - Filtration - 2 types | 1) Cellulose or plastic polymer filters 2) High efficiency particulate air filter (HEPA) |
| Filtration - 1) Cellulose or plastic polymer filters | - pore size 0.22 - 0.45 Mm (small enough to capture microbes then draw thru filter with vacuum to capture microbes) (this size filters most bacteria) |
| Filtration - 2) High efficiency particulate air filter (HEPA) | - pore size 0.3 Mm anything thats larger than dust, mold, pollen - lots of applications = surgical, burn patients, asthma sufferers |
| General info on Filtration | their are some substances that we can't heat sterilize - destroys product - vitamin solution - antibiotics - vaccines |
| Physical method of control - Low Temp - 1 type | 1) fridge and freezers - household application - put food in - slows down process doesn't prevent the process - household freezers - good slow freezing microbes which slowly allows ice crystal formations in cytoplasm which ruptures the memebrane and the wall and kills the cells |
| Physical method of control - Osmotic Pressure | review page 34 |
| Physical method of control - Radiation - 2 types | 1) Non-ionizing 2) Ionizing |
| Radiation - 1) Non Ionizing | Non Ionizing - U.V. Light 160 Nm not favored great in US - but used in other countries Expressed in Wave Lengths - the shorter the wave length the higher the energy content not high enough energy content - damages the DNA - most effective wave length - but doesn't have a high energy- problem - source UV light - hits the surface with the same water - any microbes damages DNA - but if anything else is there it won't do anything ?? NOT REALLY SURE ON WHAT PROFESSOR WAS TRYING TO SAY |
| Radiation - 2) Ionizing - | xrays, gamma rays, high energy electron beams short wave lengths - high energy content - very effective at penetrating many barriers application = eradicated milk - steril products and eradicates meat in other countries and grain silo - insects eradicate it (see backwards hamburger on UTUBE) |
| Physical method of control - Lyophilization | (- 54) degrees to (- 72) degrees AKA - freeze drying - to preserve microbes for teaching and learning grow microbes in liquid media the simulations draw off liquid with vacuum and then flash freeze them quickly - produces dry pellet - add to TSB and incubate for few days (see grocery store wars on UTUBE) |
| Chemical Methods of control - Disinfectants and Antispectics` | 1) phenol (carbolic Acid) 2) phenolics - 3) Halogens - 4) alcohols - 5) Ethylene oxide gaseous chemosterilizer - 6) Oxidizing agents - 7) Surface - 8) Quatenary Ammonium compounds (quats) 9) Aldehydes - |
| Disinfectants and antiseptics - 1) | 1) phenol (carbolic Acid) - Dr. Lister used - not used so much any more because it smells bad and irritating to living tissue ( how this works = disrupts plasma membrane and denatures enzymes) |
| Disinfectants and antiseptics - 2) | 2) phenolics - ( how this works = disrupts plasma membrane and denatures enzymes) - chemical dirivative of phenol kept good qualites and got rid of bad ones or minimized them effective if used on disinfecting body products - saliva, pus and feces |
| Disinfectants and antiseptics - 3) | 3) Halogens - inhibit protein function a) Iodine - anti-disinfectant both water and aeresol b) fluorine - used alone or combined with chlorine, used primarily to disinfect municipal water supplies b) chlorine (sodium hypochlorite) - used as gas or compressed form common = bleach (sodium hypochlorite) very effective disinfectant - denatures proteins (don't know which one the professor was talking about when she said vegetative cells and endospores sect fungi and viruses) |
| Disinfectants and antiseptics - 4) | 4) alcohols - denature proteins and dissolve lipids - kills many fungi and bacteria not so many viruses or endospores - 70% - has water added to it which is more effective than 95% alcohol- used as a microbiol agent which can penetrate cells more effectively |
| Disinfectants and antiseptics - 5) | 5) Ethylene oxide gaseous chemosterilizer - denatures proteins - highly toxic - nasty - haghly explosive - so they mix it with an inert gas nitrogen or carbon dioxide, which makes it less explosive - used to sterilize medical equipment - exposure 4 to 18 degrees in a gaseous chemosterilazer like a band aid in the sterilization process |
| Disinfectants and antiseptics - 6) | 6) Oxidizing agents - oxidizing cellular components Oz = ozone - air sterilization H202 = hydrogen peroxide - limited usefullnes on open wounds |
| Disinfectants and antiseptics - 7) | 7) Surface - active agents (surfectants) a) soaps - or detergents - little value as antiseptic - they aid in the mechanical removing of microbes b) acid - anionic sanitizers - used in dairy industry clean utensils equip wide spectrum action - kills both gram + and gram - organisms |
| Disinfectants and antiseptics - 8) | 8) Quatenary Ammonium compounds (quats) currently unknown kills bacterial membrane - usually used for cleaning gram + more effective against ??vs?? gram - |
| Disinfectants and antiseptics - 9) | 9) Aldehydes - inactivates proteins - most effective among the microbial agents a) formaldehyde - formalin 37% - aquious gas solution (old way) b) Glutaraldehyde 2% cidex - common - more effective than a) used to sterilize hospital equipment - 2% cidex kills most bacteria with a 10 minute soak |
| Antiseptic is used on what | human tissue |
| Disinfectant is used on what | surfaces |
| page 35 of handout | BACTERIAL GROWTH CURVE 1) Lag phase - little or no cell division but intense metabolic activity - gearing up todivide 2) Log phase - exponential growth of cells generation time will be at a minimum cells are at their most characteristic during log phase "best time gram stain and get results" most suseptable to adverse environment conditions, best time to treat with antibiotics 3) Stationary phase - population is leveled off - B the # of new cells produces is = to the # of cells that are dying. reasons why exhausting nutrients, avail oxygen. metabolic toxins are accumulating which cause changes in the pH "more acidic" 4) Death phase - # of cells dying exceeds the # of new cells being produced until ultimately all are dead generation time = the amount of time it takes for a cell to divide or for the time population to double in #'s |
| page 39 of handout | 2c. Heat - pg 186 beginning with "Moist Heat" Boiling Autoclaving Pasteurization Ultra-high-temperature treatments (UHT) Flaming Hot air sterilization ----how to kill or control growth why we want to control the growth - to prevent the transmission of disease and to prevent the spoilage of foods ways to control growth of microorganism - kill them - inhibit their growth - remove them "by filtration" physical methods of control |
| Disinfection | the act of disinfecting, using specialized cleansing techniques that destroy or prevent growth of organisms capable of infection. n agent, such as heat, radiation, or a chemical, that disinfects by destroying, neutralizing, or inhibiting the growth of disease-carrying microorganisms. |
| Sterilization | the process of destroying all microorganisms and their pathogenic products. |
| Antiseptic | a substance that tends to inhibit the growth and reproduction of microorganisms when applied to living tissue. |
| Bacteriocidal (germicide) | An agent that destroys bacteria |
| Bacteriostatic | adj preventing bacteria from growing and multiplying but possibly not killing them |
| Criteria for Choosing Antimicrobial Drugs | 1. Selective Toxicity 2. Lack of Hypersensitivity 3. Solubility in Body Fluids 4. Lack of Resistance in Microbes |
| Selective Toxicity | should be toxic to the pathogen but not to the patient |
| Lack of Hypersensitivity | shouldn't cause an allergic response in the patient (not the same as toxicity) |
| Solubility in Body Fluids | so it can rapidly penetrate body tissues |
| Lack of Resistance in Microbes | microbes shouldn't become resistant to the drug |
| Chemotherapy | the treatment of disease with chemicals |
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