Term
Chemical Anti-Microbial Agents
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Definition
· Types
o Phenols and phenolics
o Biguanides
o Alcohols
o Halogens
o Oxidizing agents
o Surfactants
o Heavy Metals
o Food and cosmetic preservatives
o Aldehydes
o Gaseous agents
· Kill microbes by damaging cytoplasmic membrane, proteins, DNA, or cell wall
· Effectiveness depends on
o Type of agent
o Temp
o Length of exposure
o Amount of organic matter
o pH
o Concentration
o Age of antimicrobial solution
More effective against lipid enveloped viruses and the vegetative cells of bacteria protozoa and fungi than endospores, naked viruses, and protozoan cysts |
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Term
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Definition
o Are antibiotics, semi-synthetic antibiotics, or synthetic chemicals used to control microbial growth in body of a host
o Some used outside body
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Term
Ideal chemical anti-Microbial |
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Definition
· Should be
o Inexpensive
o Fast acting
o Stable during storage
o Not affected by presence of organic material
o Compatible with soaps, detergents and other chemicals
o Able to control all microbial growth while being harmless to humans, animals, and objects
· None exists
Have advantages and disadvantages |
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Term
Principles of Effective Chemical Disinfection
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Definition
· Few chemical antimicrobials achieve sterility
o Kill vegetative pathogens and reduce microbes to safe levels
· No one chemical agent can be used safely in all situations to kill all microbes
· Differ in
o Mechanism
o Types of microbes it kills
o Time and conditions of killing
o Objects it can be used on
· Selection: Need to know
o Properties of chemical agent
o Types of microbes to kill
o How long it takes to kill
o If agent can be used on material
· Organic matter matters in agent and method
· Manufacturers directions give concentration, temp, application time, and how long diluted can be stored
Must be followed to ensure disinfection |
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Term
Methods for Evaluating Disinfectants/Antiseptics
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Definition
· 4 Methods
o Phenol coefficient
o Use-dilution tests
o Filter paper disk diffusion methods
o In-use tests
· Phenol was standard of comparison
o Doesn’t account for bacteriostatic or residual effects
· Current standard by American Official Analytical Chemists is use-dilution method
· Both phenol coefficient and use-dilution tests performed in many ways.
o 3 test microbes used
§ Staphylococcus aureus
§ Salmonella choleraesuis
Pseudomonas aeruginosa (gram negative microbe notorious for resistance to chemical antimicrobial agents) |
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Term
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Definition
· Microbes in broth cultures exposed to various concentrations of phenol for specific time
· Microbes plated
· Test disinfectant measured compared to phenol
· Ratio called phenol coefficient
Disinfectant more effective than phenol à coefficient will be greater than one |
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Term
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Definition
· He said remember name not details
metal rings adsorbed live bacteria
· Rings removed and dried
· Rings placed in various dilutions of test disinfectant for 10 mins
· Rings removed and incubated at 37 C
Acceptable use dilution kills test microbes 95% of time |
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Term
| Filter paper Disk Diffusion Methods |
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Definition
· Dip filter paper into antimicrobial agent and place onto inoculated medium
· Effective agents will have a ring of no growth (clear zone) around paper
Unreliable for agents volatile or inactivated by organic compounds |
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Term
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Definition
· Sample surface before and after use and inoculate agar medium
· Count numbers of colonies
Expensive and time consuming but accurate |
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Term
EPA has three efficacy levels
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Definition
o High – Sterilization. Kills or inactivates all life forms
o Intermediate – Kills all life forms except endospores
o Low – kills vegetative gram-positive bacteria, vegetative gram-negative bacteria, lipid enveloped viruses, but not mycobacteria, endospores, non-lipid viruses, and some fungi |
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Term
CDC uses different scheme
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Definition
· Hospital Level – low level EPA disinfectant
· Hospital level with tuberculocidal activity – intermediate EPA
Hospital level disinfectant with HIV, Hep B, Hep C activity will kill those viruses but not necessarily mycobacteria
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Term
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Definition
· Phenol (carbolic acid) first chemical to disinfect surgical wounds
· Rarely used now
o Unpleasant odor
o Irritating to skin and mucous membranes
o Toxic
· Phenolics intermediate to low level disinfectant
o Chemical derivatives of phenol
o O-phenylphenol – Lysol
o Orthocresol
o Amylphenol – Amphyl
· Intermediate to low level disinfectants
o Less irritating and toxic to humans
o Effective in killing mycobacteria but not always naked viruses
o Kill cells by damaging plasma membrane and denaturing proteins
· Usually dissolved in detergent solution to enhance ability to wet surfaces
o Remain active in presence of organic compounds
o Stable to dilutions and remain active on surfaces long after application
· One of four general types of disinfectant recommended by EPA for med/dental facilities
o Common in healthcare, labs, home (Lysol, triclosan)
· Disadvantages
o Odor
o Irritate skin
o Can accumulate to toxic levels
o Require 10 minutes contact time
· Bisphenols
o Phenol derivatives with two phenolic groups
§ Intermediate to low level
o Common bisphenols
§ Hexachlorophene (pHisoHex) effective in killing staphylococci and streptococci
· Surgical scrub and on skin
· Prescription only due to possible neurological damage if overuse
§ Triclosan
Antibacterial soaps, toothpastes, cutting boards, pillows |
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Term
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Definition
· Low level disinfectants
· Disinfect skin and mucous membranes
· Related to phenolics or bisphenols
· Chlorhexidine is best known
o Kills vegetative microbes by disrupting plasma membrane
o Effective against staphylococci and streptococci
o Prescription only in US
o Common surgical scrub
o Mouthwash – Peridex
Antiplaque agent to treat caries and perio disease |
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Term
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Definition
o Reactive non metallic iodine, chlorine, fluorine, and bromine
o Intermediate level in pure elemental and in compound state
§ Iodine and chlorine compounds common disinfectants or antiseptics
§ Bromine and fluorine rarely used
· More toxic
· Expensive
o Iodine
o Chlorine
o Bromine
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Term
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Definition
· Iodine (I2) long used as antiseptic for skin and wounds
· Kills microbes by combining with tyrosine groups and denaturing protein
· Used in tincture or iodophor
o Tincture – dissolved in 70% alcohol
§ Irritating to skin and stain objects
o Iodophor – organic moecule-iodine complex that releases I2 slowly
§ No staining and less irritating
§ Preferred
· Betadine and Isodine
o Iodophores commonly used for skin disinfection
o Iodine binding organic molecule povidine also surface wetting agent
· Wescodyne, IodoFive, and Biocide
o Iodophors to disinfect hard surfaces
o EPA- intermediate level
o One of four recommended types for surface disinfection in med/dental settings
· Disadvantages
o Diluted iodophors lose iodine at slow, constant rate and half – shelf life 1-2 weeks
o Inactivated by too much organic matter
o Pseudomonas and protozoan cysts resistant
10 minute contact time
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Term
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Definition
· Highly effective intermediate level disinfectants
· Cl2 – gas that combines with water to form HOCl – Hypochlorous acid
· HOCl enters cells and oxidizes
o Destroys proteins, lipids, nucleic acids and kills cell
· Cl2 disinfects drinking water
o Disadvantages
§ Protozoan cysts resistant
· Natural surface water often contaminated and needs filtered
§ Combines with organic matter à carcinogens
· Small enough risk to be worth it
§ Cl2 toxic and corrosive
· 5% Sodium Hypochlorite NaOCl – bleach
o Common, inexpensive, effective household disinfectant for laundry and floors
o 1/10 dilution recommended by EPA for hard surfaces in med/dental settings
o 1/10 bleach not affected by organic material
o Intermediate level – 5 minutes contact
o Disadvantages
§ Corrosive for fabrics, aluminum, and other metals
§ Irritating to mucous membranes
§ Must be removed from sensitive materials with water
· Calcium hypochlorite – solid form of chlorine that forms HOCl when mixed with water à lime water
o Commonly disinfects equipment and floors in agriculture
· Sodium dichloroisocyanurate
o Stable solid organic compound that slowly releases chlorine
o Used with NaBr in swimming pools and hot tubs
o Hospital disinfectant under name MicroStat
§ Disinfects in 5 mins
§ Tuberculocidal
§ Diluted solutions stable for 1 week
· Chlorine Dioxide ClO2
o Highly reactive gaseous form of chlorine
o Disinfects large objects in sealed chambers
o Safely inactivated by pumping through sodium bisulfite
· Chloramines
o Stable ammonia and chlorine compounds that release chlorine slowly
o Disinfect more slowly than other forms
Hospital disinfectants and drinking water |
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Term
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Definition
§ Disinfect hot tubs because evaporates slower than chlorine
§ Used with chlorine in swimming pools |
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Term
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Definition
· Ethanol and isopropanol considered intermediate level in 50-95% solutions with water
o Kills vegetative microbes but not naked viruses and fungal spores
· Denatures proteins, dissolve lipids, and disrupts membranes
· Pure alcohol ineffective and needs water to denature protein and disrupt cell membranes
· Used on hard surface and skin but not on wounds because they denature proteins in wound healing
· No residue
· Non toxic
· Disadvantages
o Evaporates quickly in thin film which may not be enough contact time
o Odor
· Enhances efficacy of other disinfectants
o Used in combo with iodine or quarternary ammonium compound
Alcohol-antimicrobial solutions called tinctures |
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Term
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Definition
· Ions denature proteins in low concentrations – oligodynamic action
o Mercury
o Silver
o Zinc
o Lead
o Copper
· Long used as antiseptics and antimicrobials
o 1% silver nitrate in eyes of newborns prevents opthalmia neonatorum caused by Neisseria gonorrhoeae
o Mercuric chloride and mercurochrome used as topical for years, no more
o Thimersol w/mercury used as preservatives in vaccines. Supposed link to autism
o Copper sulfate algicide in pools, fish tanks, paints
o Zinc chloride in mouthwashes
o Zinc oxide antifungal agent in body powders and creams and paints
o Lead used in paints and gas but no longer
· Heavy metal ions kill cells by combining with SH groups in proteins and denaturing
· Killing efficacy reduced by organic material
Clutathione protects cells from heavy metals |
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Term
Surfactants – surface-active agents
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Definition
· Soaps, anionic detergents, cationic detergents
· Decrease surface tension of water
· Allow water to wet solid surfaces fully
· Dissolve dirt, fats, grease
· Soaps – sodium salts of fatty acids
o Not effective antiseptics or disinfectants because they don’t kill most microbes
o Yet hand washing is one of most effective ways to prevent cross infections in hospitals
· Scrubbing hands with soap followed by mechanical rinse removes surface microbes by emulsifying microbes, skin cells, and skin oils in micelles
o Normal flora stay attached deeper
o Abnormal bacteria more readily removed
o Alcohol gels good substitute for handwashing and reduce infections by 50% because they are used more often than washing
· Hospital infections
o 12.2 per 1000
o Mortality 12.9% compared to 2.3%
o Average charges for infections 185K rather than 31K
>2 billion in extra charges |
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Term
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Definition
§ Stronger surfactants than soaps due to sulfonic acid at end of hydrocarbon chain rather than carboxyl
§ Good surfactants and sanitizers, but not disinfectants
· Don’t work against many gram negative
· Anionic agents disrupt plasma membrane and denature proteins of some gram positive |
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Term
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Definition
· Called quats or Quaternary Ammonium Compounds
· Cepacol and Zephiran most commonly used quats
· Good sanitizers and good surfactants
o Odorless
o Tasteless
o Non-toxic
o Common in toothpastes, body powders, and other products
· Quats poor disinfectants by themselves
· Zephiran ineffective against E. coli
· Pseodomonas can grow in quat solutions
· Zephiran tinctures kill E. coli
· Quat tinctures – Intermedate level
o EPA recommended for hard surfaces in med/dental setting but don’t work against naked viruses
o Disinfect in 5 mins, non toxic, good wet ability, and no need to wipe up
· Kill by disrupting cell membrane and denaturing proteins
· Disadvantages
o Organic matter, soaps, detergents interfere
Ineffective against Pseodomonas, many other gram-negative bacteria, and naked viruses |
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Term
Organic acids and their salts
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Definition
· Commonly used as preservatives in food, cosmetics, soft drinks
o Sorbic acid and potassium sorbate inhibit molds in acidic foods
o Benzoic acid and sodium benzoate inhibit molds in soft drinks and acidic foods
o Para-aminobenzoic acids (parabens) inhibits mold in cosmetics and shampoos
§ People allergic to parabens often allergic to local anesthetic procaine because of structurally similarity
Calcium propionate inhibits molds in bread |
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Term
Bisulfite, Nitrate, and Nitrate
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Definition
o Sodium bisulfite forms sulfur dioxide when dissolved
§ Disinfects bottles and equipment for making wine
§ Kills wild yeasts in fresh grape juice
o Sodium nitrate and nitrite commonly preserve meats – hot dogs, sausage, and lunch meats
§ Nitrite inhibits Clostridum botulinum
§ Nitrite forms nitrous acid (mutagen). Also reacts with amines to form nitrosamines (carcinogens).
§ Botulism risk greater than cancer risk |
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Term
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Definition
· Organic compounds with carbonyl end group
· Highly reactive
· High level disinfection
· React with aldehyde, amino, hydroxyl, sulfhydryl, and carboxyl groups on other molecules
· Formaldehyde and gluteraldehyde (Cidex) commonly used
o Alkylate amino, hydroxyl, sulfhydryl, and/or carboxyl groups on proteins and nucleic acids, inactivating molecules and causing cell death
o Gluteraldehyde has two aldehyde groups and can crosslink proteins or nucleic acids
· Formaldehyde
o Water soluble and sold in 37% solution (Formalin)
o Preserves specimins and cadavers
o Volatile, irritating to mucous membranes, allergenic, and carcinogenic
o Needs ventilation and handling care
· Gluteraldehyde (allergen and carcinogen)
o Less volatile and irritating
o Skin contact to be avoided
o Used to disinfect med/dental instruments before sterilization
o Cold sterilize non-autoclavable instruments (respiratory or dialysis equip)
o 2% solution
§ bacteriocidal in 10 mins
§ sporicidal in 10 hours
o Disadvantages
§ Long contact time needed
§ Must be rinsed off
Allergenic and carcinogenic to skin |
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Term
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Definition
· Gases that sterilize in closed chambers
o Ethylene oxide
o Popylene oxide
o B-propiolactone
o Chlorine dioxide
· Ethylene oxide, B-propiolactone, and propylene oxide are akylating agents with reactive 3 or 4 member rings with oxygen
o Ring reacts with amino, hydroxyl, or sulfhydral groups in proteins and nucleic acids, alkylating and inactivating, and causing cell death
· Highly penetrating but slow to sterilize
o 18 hours to sterilize then 24 hours of ventilation
o Fumes highly irritating, allergenic, poisonous, carcinogenic
Sterilize heat and water sensitive items |
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Term
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Definition
· Peroxides, Ozone, and Peracetic acid – strong oxidizing agents
· Intermediate to high level
· Kill by denaturing proteins, destroying lipids, and breaking DNA molecules
· Ozone highly reactive and formed by O2 from electrical charges or UV lights
o Some countries use to disinfect water
o Doesn’t form carcinogens
o More expensive and lasts shorter
· H2O2 kills bacterial cells and disinfects/sterilizes inanimate objects or surfaces
o Some books say inactivated by catalase from microbes
o 3% solution contains enough of excess
o Heated and sterilizes containers for ultra-high temp sterilized products
· Benzoyl peroxide in OTC acne meds
· Paracetic acid – high level disinfectant used for med equipment
o Corrosive
o Irritating to skin/mucous membrane
· Oxidizing agents effect against obligate anaerobes
Irrigate deep wounds to prevent clostridia and obligate anaerobes from causing gas gangrene |
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Term
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Definition
o Steam
o Formalin-alcohol vapor
o Dry Heat
o Ethylene Oxide
o Gluteraldehyde |
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Term
| EPA recommended disinfectants |
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Definition
Phenols(intermediate to low)
Iodophors (intermediate)
Quat tinctures (intermediate)
Sodium Hypochlorite NaOCl- bleach at 1/10 solution (intermediate) |
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