Exam 1: Sterilization, Disinfection, Decontamination Flashcards
What is sterilization?
The removing or killing of all microbes on an object or in any material (killing spores)
What does killing mean?
Making microbes unable to grow or reproduce even under the most favorable growth conditions
What does sterile mean?
Totally devoid of life, all cells are dead
What is the limiting requirement of sterilization?
Destruction of bacterial endospores, the most resistant form of life
What is disinfection?
The process of reduction or elimination of pathogenic microbes in or on materials so they are no longer a hazard
Some living microbes may persist
Is disinfection sterilization?
No
What are disinfections?
Chemical agents used on inanimate objects
What are antiseptics?
Relatively nontoxic chemical agents used on animals or people
What is decontamination?
The same as disinfection but implies a broader role including inactivation or removal of microbial toxins and pathogens
What does germicide/germicidal refer to?
An agent capable of killing most microbes rapidly
What may be an agent that is germicidal?
Bactericidal, sporicidal, fungicidal, or viricidal
What do bacteriostatic and fungistatic indicate?
That the antimicrobial agents is primarily inhibitory in its action; they prevent growth without killing
What is preservation?
The prevention of multiplication of microorganisms in formulated products, including pharmaceuticals and foods
What are simple methods for preventing exposure to undesirable microbes?
Mechanical removal- washing and scrubbing
Cooking food
Maintain normal flora
Is boiling sterilization? Why?
No. It does not kill spores
What are physical methods to control microbes?
Heat
Radiation
Filtration
What are the 4 ways that heat is used to destroy microbes?
Boiling water or steam at 100 degrees C
Dry heat at 160-170 degrees C for 1 hr or 145 degrees C for 4 hrs.
Autoclaving
Pasteurization
Is dry heat sterilization?
Yes
What is the most effective and commonly used method to achieve sterilization?
Autoclaving
Describe autoclaving
A temperature of 121 degrees C is attained when steam is at 15 psi pressure
15 minutes is effective for instrument sterilization, but longer times may be needed for media or other liquids
Is pasteurization sterilization?
No
What is UV light used to do?
Combat air-borne infections and contaminants
It is effective against vegetative cells, but some spores are resistant
What is ionizing radiation commonly used to do?
Sterilize many items, including foods and almost all disposable medical devices
What is filtration used to do?
Sterilize bacteriologic media, serum, injection fluids, and solutions or other heat sensitive
What filter should be used in filtration?
One with a pore size of 0.45 μm or less to remove all bacteria (except mucoplasmas) from solutions
Do filters remove viruses?
No, but they are used to separate bacterial from viruses for viral culture
List bacteria that are resistant to disinfectants and antiseptics from most resistant to least
Spores
Mycobateria (acid-fast gram-positives)
Gram negative bacteria
Gram positive bacteria
How do antiseptics and disinfectant differ from antibiotics?
Have a broader spectrum of activity
May have multiple targets in or on the bacterial cell
What are the major groups of chemical disinfectants?
Alcohols Ethylene oxide gas Aldehydes Halogens Phenolic compounds Quarternary ammonium compounds Biguanide compounds Peroxygens Silver compounds Mercurials Soaps or anionic detergents
Describe alcohols
Rapidly bactericidal, including many acid-fast organisms, but are not sporicidal
Widely used for hard-surface decontamination and skin antisepsis
Antimicrobial activity is optimal in the 60-90% range
Describe ethylene oxide gas
Sporicidal
It is mutagenic and explosive
Requires a long aeration time
What are the different types of aldehydes?
Glutaraldehyde
Formaldehyde
What is glutaraldehyde?
The most bactericidal compound available
Describe glutaraldehyde
Broad spectrum activity against bacteria, spores, fungi, and viruses
Has good mycobactericidal activity
Used for low-temperature disinfection of endoscopes and surgical instruments
Describe formaldehyde
Sporicidal, but require long exposure time
Mixed with alcohols it is the most effective instrument soak available
What are the different halogens?
Sodium hypochlorite (bleach) Aqueous or alcoholic solutions of iodine (tincture) Iodophors (povidone-iodine)
What is sodium hypochlorite used for?
Hard surface decontamination
What are aqueous or alcoholic solutions of iodine?
Rapidly bactericidal, sporicidal, and fungicidal, but they are unstable and associated with irritation and excessive staining
What are iodophors?
Complexes of iodine with a solubilizing agent
They are more stable, but considered less active against spores and fungi
What are phenolic compounds used as?
Antiseptics
Disinfectants
Preservatives
What is highly resistant to phenolic compounds?
Mycobacterium
What is the oldest known disinfectant?
Phenol
What are examples of phenolic compounds?
Chloroxylenol
Triclosan
What is chloroxylenol?
A broad spectrum antimicrobial effective against bacteria, fungi, and viruses
What is triclosan?
Widely used in antiseptic soaps and hand rinses
Especially effective against gram-positives
What are quarternary ammonium compounds?
Nitrogenous cationic surface active agents used for preoperative disinfections of unbroken skin, application to mucosal membranes, and disinfection of non-critical surfaces
Also used for cleaning and deodorization
Not sporicidal or mycobactericidal
When do quarternary ammonium compounds not work?
When they come into contact with organic material
What is the most widely used thing in antiseptic products, in particular in handwashing and oral products?
The biguanide, chlorhexidine
Describe biguanide compounds
Bactericidal with broad-spectrum efficacy
Not mycobactericidal or sporicidal
Describe peroxygens
Widely used for disinfection and antisepsis
Has broad-spectrum activity
Bacterial expression of catalase or other peroxidases can increase tolerance
Higher concentrations and longer exposure times are required for sporicidal activity
What are silver compounds used to do?
Prevent infection of burns and some eye infections
What are the types of acquired resistance to antiseptics and disinfectants?
Mutation
Gene acquisition
Physiologic adaptation
What has increased resistance to antiseptics and disinfectants? What is this an examples of?
Bacteria in biofilms
Physiologic adaptation
