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Decontamination; sterilization;

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Most methods of microbial control can be considered ______ - reducing or destroying unwanted microorganisms in a given area. This does not mean _____- destruction of all forms of living organisms.

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Physical; Chemical;

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Most methods use either: -____ methods-heat or radiation -____ methods- disinfectants or antiseptics.

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bacterial endospores

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Controlling Microorganisms: -Primary targets are microorganisms capable of causing infection or spoilage: -vegetative bacterial cells and endospores -fungal hyphae and spores, yeast -protozoan trophozoites and cysts -worms - viruses -prions -Because they are the most difficult to destroy, ___ ____ are the target of sterilization processes.

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Highest; Moderate; Least;

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Relative Resistance of Microbes: - _____ resistance: prions, bacterial endospores -______ resistance: pseudomonas sp, mycobacterium tuberculosis, staphylococcus aureus, protozoan cysts -______ resistance: most bacterial vegetative cells, fungal spores and hyphae, yeast, enveloped viruses, protozoan trophozoites.

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Sterilization

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A process that destroys all viable microbes, including viruses and endospores; microbicidal;

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Disinfection

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A process to destroy vegetative pathogens, not endospores; used on inanimate objects.

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Antiseptic

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Disinfectants applied directly to exposed body surfaces.

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Sanitization

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Any cleansing technique that mechanically removes microbes.

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Degermation

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Reduces the number of microbes through mechanical means.

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-cidal

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Chemical that kills.

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-static

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Chemical that inhibits growth but does not kill.

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Microbial death

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Permanent loss of reproductive capability, even under optimum growth conditions.

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Susceptibility; Active;

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Factors That Affect Death Rate: -Cells in a culture vary in _____ to a given antimicrobial agent. -The whole population DOES NOT die instantly; time is required. -____ cells (younger) tend to die more quickly than less metabolically active cells (older)

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Number; Nature; Temp and pH; Concentration; Action; Interfering organic matter, and inhibitors;

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Factors that Affect Death Rate: The effectiveness of a particular agent is governed by several factors: -____ of microbes - _____ of microbes in the population - _____ and ____ of environment -______ or dosage of agent - Mode of _____ of the agent - Presence of ______, interfering _____ _____, and ______.

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Cell wall; Cell membrane; Cellular synthetic processes; Protein function;

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Antimicrobial Agents' Modes of Action: There are 4 general categories of targets for physical and chemical antimicrobial agents: -Cell ____ -Cell ______ -Cellular _____ _____ -______ ______

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cell wall; blocking; digesting; breaking; Penicillin

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Antimicrobial Agents' Modes of Action; 1. The ____ ____- becomes fragile and cell lyses; some antimicrobial drugs, detergents, and alcohol. -Chemical agents damage the cell wall by _____ its synthesis, by _____ it or by ______ down its surface. -_____ interferes with the synthesis of the cell wall by preventing the cross-linking of the amino acid chains that link NAG and NAM in the peptidoglycan.

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cell membrane; lipids; proteins;surfactants;

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Antimicrobial Agents' Modes of Action: 2. The ___ ____- composed of ____ and ____; even some viruses have an envelope. -Provides a 2-way transport system that, if disrupted, cannot prevent loss of vital molecules nor entry of damaging chemicals. -Detergents called ____ are microbicidal because they lower the surface tension of the cell membrane.

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Cellular synthetic processes; replication; transcription; mutagenic agents; replication; formaldehyde and ethylene oxide;

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Antimicrobial Agents' Modes of Action: 3. ______ ____ _____ (DNA, RNA, proteins)- some antibiotics bind to the ribosomes in such a way that peptide bonds cannot form. -Some agents bind to DNA and prevent either ______ or ______. -Other _____ _____ may prevent DNA ______ by damaging the DNA or inactivating it. -Chemicals such as _____ and ____ ____ interfere with DNA and RNA function.

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Protein function; native state; denaturing;

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Antimicrobial Agents' Modes of Action: 4. ______ ____- interfere at ribosomes to prevent translation, disrupt or denature proteins; alcohols, phenols, acids, heat. -Many (most) proteins function properly only if they stay in their _____ ____- the normal 3-dimensional configuration. -When the shape is disrupted, the protein cannot function properly-this is known as ______ the protein.

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Moist heat; strong; phenolics; metal

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Ways to denature proteins: 1. Coagulation by ____ ____. 2. Coagulation by ___ organic solvents and _____. 3. Attachment and blocking of the active site by ____ ions.

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Heat; cold; desiccation; radiation; filtration;

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Methods of Physical Control: 1. ____-moist and dry 2. ___ temperature 3. _____ 4.______ 5. _____ (mechanical)

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Heat; moist; dry; moist heat; penetrates; coagulation; denaturation;

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____-most commonly used for sterilization. 2 types: -1. ____-uses hot water or steam. -2. ____- incineration or dry heat ovens. - ____ is more effective: -lower temperatures and shorter exposure time; _____ better than dry. -works by ______ and ______ of proteins.

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Dry heat; dehydrates; oxidizes;

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Moderate to high temperature for longer times. -____ the cells and ____ them- reduces them to ashes

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Spores; dipicolinic acid

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-_____ metabolize at a VERY slow rate. -Contain enzymes that can return them to the vegetative state when conditions are good. -Have a heat-resistant gel-like core because they have a very low water content. -_____ ____ links to and stabilizes spore proteins, giving heat resistance.

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Destruction of bacterial spores

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Primary aim of sterilization: Just because something is sterile does not mean it is harmless. Bacteria may be dead but bacterial toxins may still be present that can cause harm.

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Thermal death time

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Shortest length of time required to kill all test microbes at a specified temperature.

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Thermal death point

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Lowest temperature required to kill all microbes in a sample in 10 minutes

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Autoclaving

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Moist heat under pressure-will sterilize (kill bacterial spores)

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15-20psi/121-125 c/10-40min

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autoclave paramerters

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Steam

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___ must reach surface of item being sterilized

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Mode of action

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Denaturation of proteins, destruction of membranes and DNA.

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Tyndallization

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-Intermittent sterilization for substances that cannot withstand autoclaving. -Items exposed to free-flowing steam for 30 to 60 minutes, incubated for 23-24 hours and then subjected to steam again. -Repeat cycle for 3 days -Used for some canned foods and laboratory media. -Disinfectant only; not reliably sporicidal

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Pathogens; disinfection

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Boiling Water: -Boiling at 100c for 30 minutes to destroy non spore forming ______. -Used for ______. Not sterilization. -At higher altitudes, water boils at a lower temperature, so longer time is needed.

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Pasteurization

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-Heat is applied to kill potential agents of infection and spoilage without destroying the food flavor or value. -Not sterilization-kills non spore forming pathogen and lowers overall microbe count; does not kill endospores or many nonpathogenic microbes.

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batch; flash; ultrapasteurization; ultra high temp;

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Methods of pasteurization: -63 -66 for 30 min -71.6 for 15 seconds -82 for 3 seconds 134 for 1-2 seconds; sterilizes milk

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Dry; incineration; hot air ovens

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Dry Heat: - ____ ___ must use higher temperatures than moist heat. -_____-flame or electric heating coil. - _____ ___ ______-150-180c for at least 2 hours for coagulating proteins.

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Desiccation

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Loss of water leads to dehydration, also known as ______. -Gradual removal of water from cells, leads to metabolic inhibition. -Not effective microbial control-many cells retain ability to grow when water is reintroduced.

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Lyophilization

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Freeze drying; preservation

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Ionizing; Nonionizing;

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Radiation: -______-causes ions to form; can damage DNA and produce toxic substances. -_____-raises ions to a higher energy state but does not ionize them; leads to abnormal bond formation.

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Ionizing radiation

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-Deep penetrating power that has sufficient energy to cause electrons to leave their orbit, breaks DNA. -Gamma rays, x-rays, cathode rays. -used to sterilize medical supplies and food products.

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Short; High; positive; negative

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Gamma rays, X-rays and Cathode rays: -___ wavelengths, __ energy. -Do not use heat, use cold sterilization. -Gram ___ bacteria are more sensitive than Gram ___. -Used to sterilize heat-sensitive items and for preserving foods.

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Nonionizing; thymine dimers; higher;

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Ultraviolet Radiation: -_____ radiation-little penetrating power-must be directly exposed. -UV light creates ____ ____, which interfere with DNA replication and RNA transcription. -Can cause formation of free radicals. -The shorter the wavelength, the ____ the energy. -Can be used to kill bacteria: wavelength of 260 nm is most effective.

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Filtration

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-Physical removal of microbes by passing a gas or liquid through a filter. -Used to sterilize heat-sensitive liquids -Used to sterilize air in hospital isolation units and industrial clean rooms. -HEPA (high efficiency particulate air) filters

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Biblical times; ancient Egypt; Sulfur; Spices;

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Chemical Agents in Microbial Control: History: -____ ____: laws regarding cleanliness and dietary practices were given to prevent contamination and certain diseases. -Herbs and resins were used in ancient _____ for embalming. -____ was burned to deodorize and sanitize. - _____ used to mask odors and preserve.

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chloride of lime; iodine; copper sulfate; phenol

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-Early 1800s: Drs used _____ of ____ to wash their hands; tincture of ____ mentioned in 1830. -____ ____ used to prevent fungal diseases in plants, still used now. -1860s: Joseph Lister established principles of aseptic surgery; chose ____ as his disinfecting agent.

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Aqueous; tincture;

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-Antimicrobial chemicals can be liquid, solid, or gas -They can range from disinfectants and antiseptics to sterilants, degermers and preservatives. -Solids or gases may be dissolved in water, alcohol or a mixture of the 2. -If water is the solvent, it is known as _____. -If alcohol or water-alcohol mixture, it is called a _____.

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rapid; low; soluble; stable; broad; nontoxic; penetrating; noncorrosive; nonstaining;

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Desirable qualities of germicides: 1. ___ action in ___ concentrations. 2. ____ in water or alcohol and ____. 3. ____ spectrum antimicrobial action-will kill or inhibit both G+ and G-, as well as some fungi and viruses. 4. _____ to humans and animals. 5. _____ 6. _______ and _______. 7. Affordable and readily available.

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High level

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_____ level of chemical decontamination-kills endospores; may be sterilants. -used on devices that are not heat sterilizable and intended to be used in sterile environments (body tissue).

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Intermediate

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_____ level of chemical decontamination-kills fungal spores (not bacterial endospores), the tubercle bacillus, and non enveloped viruses.

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Low

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____ level of chemical decontamination-eliminates only vegetative bacteria, vegetative fungal cells, and some viruses - used to clean surfaces that touch skin but not mucous membranes.

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Chlorine; iodine;

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2 Halogens-nonmetallic, elements, have 7 electrons in outer shell (very reactive)

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Chlorine

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Cl2 (gas), hypochlorites, chloramines

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slowly; unstable

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Chlorine: -Denature proteins by disrupting tertiary structure. -Intermediate level; only _____ sporicidal. -_____ in sunlight, inactivated by organic matter. -Releases something that may cause formation of trihalomethanes- potentially cancer causing. -chloramines are safer

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spores; iodophores; protein folding

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Iodine: -iodophores -High concentrations will kill ____ if given long enough exposure time. -_____ are complexes of iodine and a detergent. -Interrupts metabolic functions by disrupting ____ _____. -Not adversely affected by organic matter and pH.

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Phenol

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Disrupts cell walls and membranes and precipitates proteins.

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phenol coefficient

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It is the standard by which all phenolic disinfectants are rated, though the use of a _____ _____.

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Phenol coefficient

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A number that indicates the effectiveness of an antiseptic or disinfectant compared to a phenol under identical conditions

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More

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Phenol coefficient higher than 1= chemical is ___ effective than phenol.

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less

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PC lower than 1=chemical is ___ effective than phenol.

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expensive, unpleasant odor, skin, not

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Phenolics: -Used only in limited cases because: -very ______ - _____ _____ - caustic to _____ at higher concentrations -disrupts cell walls and membranes, denatures proteins -strongly microbicidal, but ___ reliably sporicidal.

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Lysol; Bisphenols; Hexachloraphene; Triclosan;

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Phenolics-derivatives of phenol: -Low to intermediate level-bactericidal, fungicidal, virucidal; not sporicidal. - ____-phenolic combined with soap. -____-used commercially, in hospitals and clinics and in homes. - ______-once used in pHisoHex -_____- most widely used phenolic compound; used in kitty litter to soaps.

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Chlorhexidine

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-A surfactant and protein denaturant with broad microbicidal properties. -Low to intermediate level (not sporicidal) -Hibiclens, Hibitane -Used as skin degerming agents for preoperative scrubs, skin cleaning and burns

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Use-Dilution Test

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Evaluation of Disinfectants: the ___ ____ Test: -Used to offset drawback of PC test. -More practical test because it is used in a more realistic method. -Takes into consideration factors such as tissue toxicity, activity in presence of organic material or the effect of temperature variations. -Uniform method used by all who test disinfectants

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ethyl; isopropyl; surfactants; coagulating proteins; not;

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Alcohols: -Only ___ and ____ alcohol in solutions of 50-95% are useful antimicrobials. -Act as ______ dissolving membrane lipids and _____ _____ of vegetative bacterial cells and fungi. -Intermediate level -Effective skin antiseptics and used to disinfect instruments, but ___ sporicidal.

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Hydrogen Peroxide; 3%; Catalase

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-Colorless, caustic, decomposes into water and O2 -Weak to strong (3-30%); ___ is used to rinse wounds, scrapes and abrasions and is used as a mouthwash. -produces highly reactive hydroxyl free radicals that damage protein and DNA while also decomposing to O2 gas-toxic to anaerobes. -_____ (enzyme) inactivates H2O2 -Antiseptic at low concentrations; strong solutions are sporicidal (25%-30%)

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Aldhydes; sterilizing; Glutaraldehyde; Formaldehyde

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_______: -______ agents that kill by inactivating protein and DNA. -_______ and ______ are used most often. -Glutaraldehyde is effective for sterilization -High level; kills spores in 3 hours -Not adversely affected by organic materials -Non-corrosive, less toxic than formaldehyde

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Formaldehyde; Formalin;

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-A gas that readily dissolves in water, a solid at low temperatures. -Disinfectant, preservative; toxicity limits use - _____ 37% aqueous solution -Intermediate to high level; kills spores in 12-18 hr.

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Ethylene oxide; chlorine dioxide; carcinogenic; sporicidal;

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Gases and Aerosols: -____ ___ (ETO); propylene oxide; ______ ____ (CIO2) -ETO is ______ and dangerous to handle. - CIO2 is not a carcinogen, produces no toxic by products; used in senate office building after anthrax attack. -High level; _____ -Sterilizes and disinfects plastics and prepackaged devices, food, etc.

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Detergents

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Act as strong wetting agents that reduce surface tension; polar molecules. -Cationic detergents (quaternary ammonium compounds, also called "quats") release positively charged ions in solution. -The most effective -Attracted to phosphate groups in the cell membrane.

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Quats; low; soaps;

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-____ act as surfactants that alter membrane permeability of some bacteria and fungi. -very ___ level -____-alkaline compounds weak antimicrobials. -They are degerming agents that mechanically remove soil and grease containing microbes. -Work because they are wetting agents

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Wetting agents

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emulsify particles and remove them from skin

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Heavy metals

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-Large atomic weights and complex electron shell configurations -Only silver and mercury are used today. -very toxic -low level; have no effect on bacterial spores

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toxic; allergic reactions; neutralized; resistance

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Disadvantages to heavy metal use: 1. ____ to humans 2. Often cause _____ _____. 3. _____ by large amounts of organic materials. 4. Microbes can develop ____.

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Aniline

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_____ dyes are very active against gram positive species of bacteria and various fungi. -Sometimes used for antisepsis and wound treatment -Low level, narrow spectrum of activity

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Dyes

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____ can interfere with cell wall synthesis or DNA replication. -Triphenylmethane dyes-malachite green and crystal violet -Useful antiseptics against some bacteria. genitan violet for trench mouth and thrush.

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Acridine

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_____ dyes-once used as antiseptics in medical and veterinary clinics.

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Low; acetic; propionic; lactic; benzoic; sorbic;

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Acids and Alkalis: -___ level of activity -Organic acids prevent spore germination and bacterial and fungal growth. - ____ acid-inhibits bacterial growth - ____ acid retards molds - ____ acid prevents anaerobic bacterial growth -____ and ____ acid inhibit yeast.

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pH

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Acids and Alkalies: -Very low or very high ___ can destroy or inhibit microbes.

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Aqueous solutions

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Found in detergents, cleansers, and deodorizers

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Organic acids

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Are added to bakery products, beverages, syrups, and margarine

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