Controlling Microbial Growth Flashcards
Memorize all the terms know everything!! (25 cards)
Antisepsis
Reduction in the number of microorganisms and viruses on living tissues.
-Safe to use on Skin
-Examples: Iodine, Alcohol
Aseptic
Refers to an environment or procedure free of pathogenic contaminants
-Area free of pathogens
-Examples: Hand washing, preparations of surgical field.
-cide/-cidal
indicating destruction of a type of microbe
-To kill or destroy microbes
-Example: Bactericide/ Fungicide
Disinfection
Destruction of most microorganisms and viruses on nonliving tissues
-To kill non living tissues
-Example: Soap, alcohols
Pasteurization:
Use of heat to destroy pathogens and reduce the number of spoilage microorganisms
-Example: Milk, Fruit Juice
Sanitization
Removal of pathogens from objects to meet public health standards
-Example: Washing tableware in hot water
Antimicrobials
Disinfecting agents that are naturally produced by microorganisms
-static/-static
indicating inhibition, but not complete destruction of microbes
-Does not allow growth of something but does not kill it (Refrigerator)
-Example- Bacteriostatic, fungistatic
Sterilization
Destruction of all microorganisms and virus in or an object
-Kill all microorganisms
-Example- preparation of microbiological culture media
Actions Antimicrobial Agents
(Next topic)
-If you want to kill bacteria attack cell wall, No harm will be done to humans because we not have cell wall
Alteration of cell wall and membranes
Cell wall maintains integrity of cell
-When damaged , cell burst
Cytoplasmic membrane controls passage of chemicals into and out of cell.
When damaged cellular contains leak out due to osmotic pressure
Damage to proteins and nucleic acids
Protein function depends on 3-D shape
-Extreme heat or certain chemicals denature proteins
-Damage to nucleic acid would also affect protein synthesis
Chemicals, radiations and heat can alter/destroy nucleic acids
-produce fatal mutants
-Halt protein synthesis through action on RNA
*Important
Ideally, Agents should be
-Inexpensive
-Fast-acting
-Stable during storage
-Capable of controlling microbial growth whole being harmless to humans, humans, animals and objects
Heat related Methods
(Next topic) Boiling and Autoclaving
Next topic
Most Heat (Boiling)
-Kills vegetative cells of bacteria and fungi, protozoa, most viruses
-Boiling time is critical (Different elevations require Different bowling times)
-Endospores, protozoans, cysts and some virus can survive
Moist Heat (Autoclaving)
-Pressure applied to Boiling water prevents steam from escaping
-Boiling temperature increases as pressure increases
-Autoclave conditions- 121°C, 15 psi, 15 minutes
Moist Heat (Pasteurization)
-Not sterilization (Heat tolerant Microbes survived)
-Used for milk, ice cream, yogurt and fruit
Incineration
-Burns Items completely
(Can be used to discard public waste)
(An effective mean of sterilization)
Refrigeration and Freezing
Decrease microbial metabolism, growth, and reproduction
-Chemical reaction occurs more slowly at low temperatures
-Liquid Water not available
Psychrophilic microbes can multiply in refrigerated foods
Refrigeration halts growth of most pathogens (DOES NOT KILL BACTERIA)
Slow freezing more effective than quick freezing (If you freeze bacteria you can kill most Bacteria)
Organisms vary in susceptibility to freezing
Desiccation and Lyophilization
Desiccation=to dry (Test Question)
Lyophilization-remove water (test Question)
-Drying inhibits growth because of removal of water. (Dry heat is an effective means of sterilization)
-Lyophilization used for a long term of preservation. (Prevents formation of damaging ice crystals)
Radiation
-Ionizing radiation –>Wavelengths shorter than 1nm, Ejects electrons from atoms to create ions, Ions disrupt hydrogen bonding (Can denture DNA)
-Gamma irradiation is used for fresh fruits and vegetables
Alcohols
-Intermediate level of
-Denature proteins and disrupts cytoplasmic membranes
-More effective than soap in removing bacteria from hands
- Used for both antiseptics and disinfection (Swabbing of skin with 70% of ethanol
