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Microbiology CH5

Control of Microorganisms in the Environment

QuestionAnswer
__________ : Destruction or removal of all viable organisms Sterilization
___________ : Killing, inhibition, or removal of disease pathogenic organisms Disinfection
__________ : agents, usually chemical used for disinfection Disinfectants
On what objects disinfectants are used? inanimate objects
__________ : reduction of microbial population to levels deemed safe Sanitizations
__________ : prevention of infection of living tissue by microorganisms Antisepsis
__________ : chemical agents that kill or inhibit growth of microorganisms when applied to tissue Antiseptics
Which of the following is the strongest in terms of killing? Sterilization - Disinfection - Sanitization - Antisepsis Sterilization
Which of the following is applied to tissue? Disinfectant - Antiseptic Antiseptic
___________ : Use of chemicals to kill or inhibit growth of microorganisms within host tissue Chemotherapy
___________ : Agents that kill microorganisms or inhibit their growth Antimicrobial Agents
____ : Suffix indicating that agent kills Cide
________ : Kills pathogens and many nonpathogens but not necessarily endospores Germicide
Examples of cidal agents Bactericides - fungicides - algicides - viricides
_______ : Suffix indicating agents that inhibits growth Static
Examples of static agents Bacteriostatic - fungistatic
True or False: Microorganisms are killed instantly False
What is D value? Decimal reduction time - time to kill 90%
What are persister cells? Bacteria in the stationary phase that are trying to survive cidal & static agents
What factors influence the effectiveness of antimicrobial agent activity? Population size - Popular composition - Concentration of intensity of an antimicrobial agent - Duration of exposure - Temperature - Local environment
What conditions of Population size insure the most effectiveness of an antimicrobial agent? The smaller the population the shorter time it takes to kill the population
True or False: microorganisms are all equally sensitive to antimicrobial agents False, microorganisms differ markedly in their sensitivity to antimicrobial agents
What is the relation between concentration or intensity of an antimicrobial agent & its effectiveness? Higher concentration will kill more rapidly
True or False: The relationship between concentration or intensity of an antimicrobial agent is not linear True
What conditions of duration of exposure insure the most effectiveness of an antimicrobial agent? The longer the duration the more organisms are killed
What conditions of Temperature insure the most effectiveness of an antimicrobial agent? Higher temperature usually increase the killing of organisms
What local environment conditions affect the effectiveness of an antimicrobial agent? pH, viscosity, concentration of organic matter
True or False: Filtration is a physical removal method False, it is a Mechanical removal method
How does Filtration work? It reduces microbial population or sterilizes solutions by removing microorganisms & reducing microbial population in air
How can liquids be filtrated? Bu membrane filters
_________ ______ : Porous membranes with defined pores sizes that remove microorganisms primarily by physical screening Membrane filters
How can air be filtrated? Surgical Masks - Cotton plugs on cultural vessels - HEPA filters
What does "HEPA" filters stand for? High efficiency particulate air filters
Where are HEPA filters utilized? In biological safety cabinets
What are the 2 physical control methods? Heat & Radiation
What does Moist Heat do? Destroys viruses, fungi, and bacteria
True or False; Boiling sterilize and destroy spores False, boiling does not destroy spores and does not sterilize
In what mechanism does Moist Heat destroy microorganisms? By degrading nucleic acids, denaturing proteins, and disrupting membranes
What is the best sterilization process that is effective against all types of microorganisms including spores? Steam Sterilization
At what temperature steam sterilization is carried? Above 100 C
What is the machine used to carry out steam sterilization? Autoclave
________ : Controlled method of heating at temperature below boiling Pasteurization
What is Pasteurization used for? Milk, beer and other beverages
True or False: Pasteurization sterilizes True
How does Pasteurization kill pathogens? It kills present pathogens and slow spoilage by reducing the total load of organisms present
What is the difference between Dry Heat Sterilization & Moist Heart Sterilization? Dry Heat Sterilization is less effective, requires higher temperatures and longer exposure times
At what temperature and duration Dry Heat method works? 160 - 170 C for 2-3 hours
At what mechanism does Dry Heart Sterilization works? By oxidizing cell constituents & denaturing proteins
How to sterilize inoculating loops in microbiology labs? By Dry Heat sterilization using a bench top incinerators
What wavelength of UV radiation is most bactericidal? Wavelength of 260
What is the mechanism of UV radiation sterilization? Causes thymine dimers preventing replication and transcription
What is the limitation of UV radiation sterilization? Limited to surface sterilization, because it does not penetrate glass, dirt films, water, and other substances
What type of radiation penetrates deep into objects? Gamma Radiation
True or False: Gamma radiation destroys bacterial endospores True
True or False: Gamma radiation is effective against viruses False, it's not always effective against viruses
What is Gamma Radiation used for? To sterilize antibiotics, hormones, sutures, plastic disposable supplies, and food
What are chemical control agents? Disinfection - Antisepsis - Sterilization
What are the requirements for chemical agents to be considered effective? Must be effective against wide variety of infectious agents at low concentrations - Must be effective in the presence of organic matter (water) - Must be stable in storage
What causes Triclosan Resistant? Overuse of the antiseptic Triclosan
Where are Phenolics commonly used? Disinfectants in laboratory and hospitals
What is the mechanism of Phenolics? Denaturing proteins & disrupting cell membranes
What Phenolic combination is effective in the presence of organic material? Also long lasting? Tuberculocidal Disinfectant
What is the disadvantage of using Phenolics? Unpleasant odor and skin irritation
What are the most commonly used Alcohols for disinfection? Ethanol & Isopropanol
True or False: Alcohols are Bactericidal True
True or False: Alcohols are fungicidal True
True or False: Alcohols are sporicidal False, they are not sporicidal
True or False: Alcohols are effective against viruses True, they can inactivate some viruses
In what mechanism do Alcohols work? By denaturing proteins and possibly dissolving membrane lipids
What are the 5 elements of Halogens? Fluorine, Chlorine, Bromine, Iodine, Astatine
Where is Fluorine utilized? In toothpaste
Where is Chlorine utilized? Chlorine
What are Halazones? Chlorine based tablets that were used for portable water purification
How is Iodine utilized in reference to the skin? It is a skin antiseptic
In what mechanism Iodine works? It oxidizes cell constituents & iodinates proteins
True or False: Iodine can kill spores at low concentration False, it can only kill spores in high concentrations
What are the disadvantages of using Iodine? Skin damage, staining, allergies
What is Iodophor? Iodine complexed with organic carrier - minimize skin burns
What is Chlorine used for? Disinfection of water supplies and swimming pools - used in daity and food industries - household disinfectant
What type of microorganisms does Chlorine kill? Vegetative bacteria & fungi
Which form of Chlorine is sporicidal? Chlorine gas
What happens when chlorine reacts with organic matter? It forms carcinogenic compounds
Created by: Nour Dabbagh
 

 



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