Micro ch 5

Joseph Lister

• the removal or destruction of all microorganisms and viruses on or in a product
• Destruction means they cannot be "revived" to multiply even when transferred from the sterilized product to an ideal growth medium
• *Sterile DOES NOT consider prions, as they are not destroyed by standard sterilization

• the elimination of most or all pathogens on or in a material
• Generally implies use of antimicrobial chemicals
• Unlike sterilization, disinfection suggests that some living microbes may remain

• are antimicrobial chemicals used for disinfecting inanimate objects
• toxic to many forms of life and therefore biocides (bio means life, cida means to kill)
• Often called germicides
• Target microorganisms and viruses

• another term for disinfectant and germicide
• meaning they kill bacteria

• antimicrobial chemicals non-toxic enough to use on skin or other body tissue
• routinely used to decrease bacterial numbers on skin before invasive procedures such as surgery

• process used to reduce the number of pathogens to a level considered safe to handle
• tx can be as simple as thorough washing, or it may involve the use of heat or disinfectants

• generally implies a process that substantially reduces the microbial pop to meets accepted health standards
• most people also expect a sanitized object to look clean
• *this term does not indicate any specific level of control

• the process of delaying spoilage of foods or other perishable products
• One way is to adjust storage conditions to slow microbial growth
• Another is to add chemical preservatives

• inhibits the growth of bacteria but do not kill them
• Ex: a chemical

use of specific methods to prevent microorganisms from contaminating an environment

occurs when chlorine and other disinfectants react with naturally occurring chemicals in the water

• Decimal reduction time
• the time required for killing 90% of a bacterial population under specific conditions
• Temp for the process is indicated by a subscript (Ex: D₁₂₁)

dirt, grease, and body fluids such as blood can interfere with heat penetration and the action of chemicals disinfectants

• According to their risk for transmitting infectious agents; those that pose greater threats require more rigorous germicidal procedures.
• Groups include:
• Critical instruments- direct contact with body tissues, like needles and scalpels. These are critical instruments that must be sterile
• Semicritical instruments- come into contact with mucous membranes, but don't penetrate body tissue. Include GI scopes
• Non-critical instruments and surfaces- come into contact with only unbroken skin so little risk. Includes countertops, stethoscopes, and BP cuffs

• Moist Heat
• Dry heat
• Filtration
• Radiation
• High Pressure

• Denatures proteins.
• Relatively fast, reliable, safe, and inexpensive
• Includes:
• Boiling
• Pasteurization
• Pressurized steam (autoclaving)

• Boiling for 5 minutes destroys most microorganisms and viruses
• a notable exception is endospores
• *5 min boiling can be used to treat drinking water

• Developed by Louis Pasteur, as a way to prevent wine spoilage
• foods and inanimate objects can be pasteurized
• Significantly decreases the numbers of heat-sensitive microorganisms, including spoilage microbes and pathogens (except sporeformers)

• High-temp-short-time
• The way most pasteurization is done today
• Milk is pasteurized by heating to 72° C for 15 sec. 
• Parameters must be adjusted to product. Ex: Ice cream is rich in fats so it is pasteurized at 82°C for 20 sec

• Ultra-High-Temp
• Used to treat shelf-stable boxed juices and milk, as well has single-serving containers of half-cream in restaurants
• Destroys all microorganisms that can grow under normal storage conditions

• also called autoclaving
• Typical treatment is 121° C/15 psi for 15 min or longer
• A process that destroys endospores
• *Widely used to sterilize microbiological media, lab glassware, surgical instruments, and other items that steam can penetrate.
• Canning process renders foods commercially sterile
• Tape that turns black at high temp is attached to signal the item was treated

• refers to canned foods, meaning that the endospores of some thermophiles may survive
• Usually not a concern, however, as they grow only in temps well above normal storage ranges

• Not as effective as moist heat in killing microbes, and therefore requires longer times and higher temps
• Includes:
• Incineration
• Dry heat ovens

• Burns cell components to ashes
• Flaming of wire inoculating loops
• Also used to destroy medical wastes and contaminated animal carcasses

• Destroys cell components and denatures proteins
• Less efficient than moist heat, requiring longer times and higher temps
• Lab glassware is sterilized by heating at 160° to 170° for 2-3 hours.
• Powders, oils, and other dry materials are also sterilized in ovens

• filter retains microbes while letting the suspending fluid or air pass through small holes
• Includes filtration of fluids and air

• Various pore sizes are available; 0.2 μm is commonly used to remove bacteria
• Used for beer and wine, and to sterilize some heat-sensitive meds

• Also called membrane filters
• paper thin, have microscopic pores that allow liquid to flow through while trapping particles too large to pass

• trap material within thick porous filtration material such as cellulose fibers
• Have complex passages that retain microorganisms while letting the suspending fluid pass through small holes

• HEPA filters are used to remove microbes that have a diameter of 0.3 μm or greater.
• Used in biological safety cabinets, specialized hospital rooms, and airplanes.

• High-efficiency particulate air filter
• remove nearly all airborne particles 0.3 μm or larger
• Used to keep microbes out of specialized hospital rooms designed for pts with extremely susceptible to infection

• Includes radio waves, microwaves, visible and UV light waves, Xrays and gamma rays
• Form of energy that travels in waves and has no mass
• Amt of energy is related to wavelength, with is distance from crest to crest fo wave
• Wavelength is proportional to frequency, the number of waves per sec
• Radiation that has short waves, and therefore high frequency, has more energy than that which has long waves and low frequency

• Type of cell damage depends on the wave length of the radiation
• Includes:
• ionizing and ultraviolet radiation

• Has enough energy to remove electrons from atoms
• This harms cells directly by destroying DNA and damaging cytoplasmic membranes
• Reacts with O2 to product ROS (reactive  oxygen species) that damages other cell components
• Bacterial endospores are among most radiation-resistant while Gram-neg bacteria (Ex: Salmonella & Pseudomonas) are most susceptible
• Items can be sterilized even after packaging
• Used to sterilize heat-sensitive materials including med equip, disposable surgical supplies, and drugs such as penicillin
• Also used to destroy microbes in spices, herbs, and approved types of produce and meats

• In wavelengths of approx 220 to 300 nm destroys microbes by damaging DNA
• Actively multiplying most easily killed, whereas bacterial endospores are most UV resistant
• Penetrates poorly. Even thin film of grease on UV bulb can make it less effective
• Used to destroy microbes in the air and drinking water, and to disinfect surfaces

• Don't affect microorganisms directly, but heat they generate can be lethal
• *Remember, however, that microwave ovens often heat foods unevenly, so even heat-sensitive cells can sometimes survive the process

• Treatments of 130,000 psi are thought to denature proteins and alter the permeability of the cell
• Products retain color and flavor
• Used to extend the shelf life of certain commercial food products such as guacamole

• Sterilants
• High-level disinfectants
• Intermediate-level disinfectants
• Low-level disinfectants

• Can destroy all microorganisms, including endospores and viruses
• Also called sporicides
• Destruction of endospores usually requires 6-10 hr tx
• Used to trx heat-sensitive critical instruments such as scalpels

• Destroy all viruses and vegetative microorganisms, but do not reliably kill endospores
• Most are simply sterilants used for short time periods, not long enuf to ensure endospore destruction
• Used to treat semicritical instruments such as GI endoscopes

• Destroy all vegetative bacteria including mycobacteria, fungi, and most, but not all, viruses
• Do not kill endospores even with prolonged exposure
• This group is used to disinfect non-critical instruments such as stethoscopes

• Destroy fungi, vegetative bacteria except mycobacteria, and enveloped viruses
• Do not kill endospores, nor do they always kill naked viruses
• Intermediate and low level also called general purpose disinfectants
• In hospitals, used for disinfecting furniture, floors and walls

• Chemical used as germicide
• (Ethanol and isopropanol)
• Easy to obtain and inexpensive
• Rapid evaporation limits their contact time
• Aqueous solutions of 60-80% are used as antiseptic to clean skin in preparation for procedures that break intact skin, and disinfectants for treating instruments
• Quickly kill vegetative bacteria and fungi
• Do not destroy bacterial endospores and some nakes viruses
• Denatures essential proteins

• Chemical used as germicide
• Capable of destroying microorganisms and viruses by inactivating proteins and nucliec acids
• *immersion in 2% solution for 10-12 hrs kills all microbes, including endospores and viruses
• Irritating to the respiratory tract, skin, and eyes
• Glutaraldehyde and orthophthalaldehyde are used to sterilize med instruments
• Formalin is used in vaccine production and to preserve biological specimens

• Chemical used as germicide
• (chlorhexidine)
• Relatively low toxicity
• Destroys a wide range of microbes, adheres to and persists on skin and mucous membranes
• Widely used as an antiseptic in soaps and lotions, and is often impregnated into catheters and surgical mesh, used in mouthwashes

• Chemical used as germicide
• easily penetrates hard-to-reach places and fabrics and does not damage moisture-sensitive material
• It is toxic, explosive and may be carcinogenic
• Commonly used to sterilize med devices
• Destroys all microbes, including endospores and viruses, by reacting with proteins

• Chemical used as germicide
• (chlorine and iodine)
• Chlorine solutions are inexpensive and readily available; however, organic compounds and other impurities neutralize the activity. 
• Some forms of chlorine may react with organic compounds to form toxic chlorinated products
• Widely used to disinfect inanimate objects, surfaces, drinking water, and wastewater.
• Iodine is more expensive and DOES NOT readily kill endospores.
• Tincture (Iodine mixed with alcohol) of iodine and iodophors can be used as disinfectants or antiseptics
• *For unknown reasons, Pseudomonas species survive in concentrated stock solutions of idophores

• Chemical used as germicide
• Most metal compounds are too toxic to be used medially
• Silver sulfadiazine is used in topical dressings to prevent infection of burns. 
• Silver nitrate drops can be used to prevent eye infections in newborns
• Some metal compounds are used to prevent microbial growth in industrial processes

• Chemical used as germicide
• Unstable form of O2 readily breaks down to an ineffective form
• Used as alternate to disinfect drinking water and wastewater

• Chemicals used as germicide
• Includes hydrogen peroxide and peracetic acid
• Readily biodegradable and less toxic than traditional alternatives
• Effectiveness of hydrogen peroxide as antiseptic is limited due to enzyme catalase breaks it down
• Hydrogen peroxide used to sterilize containers for aseptically packages juices and milk
• Peracetic acid is more potent germicide than hydrogen
• Widely used to disinfect and sterilize med devices

• Chemicals used as germicide
• triclosan and hexachlorophene ~ active ingredient in Lysol
• Wide range of activity, reasonable cost, remains effective in presence of detergents and organic contaminants, leaves an active antimicrobial residue
• Triclosan used in variety of personal care products including toothpastes, lotions, soaps, etc.
• Hexachlorophene is highly effective against Staph aureus, but use is limited as it can cause neuro damage

• Chemical used as germicide
• Benzalkonium Chloride and Cetylpyridinium
• Non-toxic enuf to be used on food preparation surfaces.
• Inactivated by anionic soaps and detergents
• Widely used to disinfect inanimate objects and to preserve non-food substances

Staph aureus

• freeze-drying
• widely used for preserving foods
• when water is added, it reconstitutes