Test 4 Study Guide Flashcards
sterilization
The complete removal or destruction of all viable microorganisms. Used on inanimate objects.
Ex. Autoclaving, ionizing radiation
disinfection
The destruction or removal of vegetative pathogens but not bacterial endospores. Usually used only on inanimate objects.
Ex. 5% bleach, boiling water
antisepsis
Chemicals applied to body surfaces to destroy or inhibit vegetative pathogens.
Ex. lodophors, antibacterial soap, chlorhexidine
sanitization
any cleansing technique that removes microorganisms from inanimate surfaces to reduce the potential for infection and spoilage
Ex. Dishwashing, laundering clothes
degermation
reduction of microbial load from living tissue by mechanical means
Ex. Surgical handscrub, alcohol wipes
pasteurization
kills non-spore-forming pathogens and lowers overall microbe count; does not kill endospores or many nonpathogenic microbes
sterilizing conditions
Sterilization with Steam Under Pressure
Nonpressurized Steam
Boiling Water: Disinfection
Hot Air and Incineration
Ionizing radiation
thermal death time
shortest length of time required to kill all test microbes at a specified temperature
thermal death point
lowest temperature required to kill all microbes in a sample in 10 minutes
infection
a condition in which pathogenic microbe penetrate host defenses, enter tissues, and multiply
disease
an infection that causes damage or disruption to tissues and organs
resident microbiota
microbes that become established in the body
transient microbiota
microbes that occupy the body for only short periods
endogenous agents
already exist on or in the body (normal flora)
exogenous agents
originate from source outside the body
Conditions for killing different microbes
physical
chemical
mechanical
Mode of operation of aldehydes
Kill by alkylating protein and DNA
Glutaraldehyde
• In 2% solution (Cidex)
• High level
• Used as sterilant for heat sensitive instruments
Formaldehyde
• Formalin – 37% aqueous solution
• Intermediate to high level
• Disinfectant, preservative, toxicity limits use
Mode of operation of detergents
Detergents: Polar molecules, surfactant
• Quaternary ammonia compounds (quats) act as surfactants that alter membrane permeability of some bacteria and fungi
• Very low level
Soaps: alkaline compounds
• Mechanically remove soil and grease containing microbes
• Weak microbicides, destroy only highly sensitive forms (gonorrhea, meningitis, and syphilis)
Mode of operation of alcohols
Alcohols exhibit rapid broad-spectrum antimicrobial activity against vegetative bacteria (including mycobacteria), viruses, and fungi but are not sporicidal. They are, however, known to inhibit sporulation and spore germination, but this effect is reversible.
Mode of operation of other chemicals
s
ionizing radiation
deep penetrating power sufficient energy to cause electrons to leave their orbit
Gamma rays
X rays
Cathode rays
non-ionizing radiation
little penetrating power
Ultraviolet (UV) radiation
Benefits of filtration as a methods of control
Physical removal of microbes by passing a gas or liquid through filter.
Used to sterilize heat sensitive liquids and air in hospital isolation units and industrial clean rooms.
Benefits of heat as a method of control
Heat can kill microbes by altering their membranes and denaturing proteins.
Benefits of radiation as a method of control
Cold sterilization of packaged products such as medical supplies and instruments that cannot be heat sterilized.
Sterilization of foods, including fruits, lettuce and spinach, grains, spices, meats, and packaged meals.
Sterilization of drugs and vaccines.
Rapid and penetrating, prevents infection and spoilage.
Examples of physical methods of control
Incineration Dry oven Steam under pressure Boiling water, pasteurization Ionizing and non-ionizing radiation
Examples of chemical methods of control
Gases
Liquids
Examples of mechanical methods of control
Filtration: air (disinfection) or liquid (sterilization)
Examples of microbial portals of entry and exit
Infectious agents enter the body through various portals, including the mucous membranes, the skin, the respiratory and the gastrointestinal tracts.
Difference between virulence factors and infectious doses and their examples
Infectivity is the ability of the infectious agent to pass from a sick to a susceptible healthy individual and cause disease.
Virulence determines how severe will be the disease in the infected individual.
Ex. toxins, surface coats that inhibit phagocytosis, and surface receptors that bind to host cells, capsules, exoenzymes, endo and exotoxins.