Antiseptics and Disinfectants Flashcards
Contrast the terms sterilization, sanitization, disinfection, and antiseptic
- sterilization: destruction of all forms of life (inclu. microorganisms)
- sanitization: reduces pathogen load by 99.9%
- disinfectant: destroys pathogenic organisms, usually on inanimate objects (reduces pathogen load by 99.99%)
- antiseptic: prevents or arrests the development of microorganisms on living tissue
Be able to rank the relative resistance to disinfection of various etiologic agents.
- low level: medium sized lipid viruses (enveloped), vegetative bacteria, fungi, small non-lipid viruses (unenveloped)
- intermediate level: tubercle bacilli, coccidial oocysts, protozoal cysts
- high level: bacterial spores
- extremely resistant: prions (survives most sterilization methods, including rendering)
How effective, relatively speaking, are dry heat, boiling water, and autoclaving as sterilization
methods?
- dry heat: inferior to moist heat, causes drying of cells, limited number of items can withstand the temperatures (320-340 F)
- boiling: kills vegetative cells of bacteria, fungi, protozoan trophozoites, and most viruses (temp cannot exceed 100 C at sea level)
- autoclaving: standard method, moist heat under pressure, addition of ethylene oxide exhibits bactericidal and sporicidal activity
What are the risks associated with the use of ethylene oxide as a sterilization agent?
Toxicity, carcinogenicity, and explosive risk require special equipment and venting for proper use
Why is “peroxide plasma sterilization” replacing ethylene oxide as the preferred method of
sterilizing heat sensitive items?
Hydrogen peroxide at 58% in the presence of an electromagnetic field becomes a gas plasma
- has a larger safety margin than ethylene oxide
What size micron filter should be used to filter fluids in order to remove bacteria and fungi?What
etiologic agents will filtration not remove?
- 22 and 0.45um pores to filter most bacteria
- do not retain spirochetes, mycoplasmas, viruses
- mostly used to sterilize liquids that will not withstand autoclaving
UV light is sometimes used in biocontainment hoods for sterilization/disinfection.What are its limitations?
Works to break molecular bonds within microorganismal DNA
- only effective for line of sight surface disinfection
- directly looking at UV light can damage retina and cornea
Does gamma ray sterilization leave a treated object radioactive?
No, dislodges electrons from atoms and forms ions leading to free radical production
Name the only high‐level disinfectant in common use in veterinary practice.
Glutaraldehyde 2% (Cidex)
- penetrates spores better than formaldehyde, item must be rinsed with sterile saline or water prior to use on a patient
- requires 10-30 minutes of contact time, exposure of 6-10 hours produces sterilization
- most commonly used for endoscopes
Contrast which bacteria are killed for a high‐level versus a low‐level disinfectant.
- high level: kills bacterial spores. used on critical items that impart risk of infection to patient if contaminated
- low level: effective on vegetative microorganisms but not spores or tubercle bacilli. also used on noncritical items that carry limited risk of inducing infection
How does an iodine “tincture” differ from an iodine “solution”?
Tinctures contain ethanol and are more efficacious, but more toxic to tissues than aqueous solutions
Povidone iodine solutions can be used for use as wound lavage solutions over a wide range of v/vdilutions. Name the upper and lower limits of that range.
Less toxic to tissues, and is the only iodine recommended for use in wounds
- 0.1 to 1% used to lavage wounds
- 10% solution diluted 1:10 to 1:100 v/v in water
- least residual activity of the antiseptics
Name an antiseptic restricted to use on skin (not wounds) that accumulates with time having a long
residual activity.
- chlorhexadine: scrub formulation used only on skin (1:40 v/v dilution)
- benzoyl peroxide: only against gram-pos bacteria (pyodermas, follicular flushing), most repository of the skin antiseptics!
How does EDTA enhance the activity of an antibiotic used topically?
Is a chelator of di and trivalent cations, which are required by bacteria (pseudomonas, proteus, e coli, and staph) to maintain cell wall integrity
- combo with Tris to adjust pH
- synergistic with antibiotics by damaging the cell membrane (MICs decrease by 100x)
- used in multi-resistant bladder infections, wounds, fistulas
Pseudomonas and yeast are unusually sensitive to what common household food item that can be
used as an antiseptic?
Acetic acid - 3% solution recommended, or distilled white vinegar of 5%
- well tolerated below 5%
- gram negs are also affected
What agents are often used a foot baths in cattle and sheep?(You do not have to know the
concentrations used.)How does dirt and manure affect the efficacy of these foot baths?
- zinc sulfate: used in sheep to avoid copper exposure
- copper sulfate: most common, some concern about environmental contamination
- formalin: good for heel warts, toughens sole (overuse can crack hoof wall)
- dirt and manure will decrease efficacy*
What v/v dilution of chlorhexadine is used as an antiseptic, particularly to lavage wounds?
1:40 v/v dilution is considered to be non-toxic to tissues
What are the ingredients found in a Modified Dakin’s antiseptic solutions?
Dilute solution of sodium hypochlorite
- used as antiseptic for wounds (surface only!) and for debridement
- buffer with sodium bicarbonate (1/2 teaspoon per 32 ounces)
Name two agents historically used as wound antiseptics that are now known to be too toxic to the tissues for this use.
- benzoyl peroxide: only safe for pyodermas
- hydrogen peroxide: only clean intact skin
- free iodine solutions
What category of disinfectant should be used cautiously especially around cats?
Phenols
- lysol, beaucoup, amphyl
Name two disinfectants that maintain their activity in organic debris.
- phenols
- chlorhexadine: must be in contact for at least 5 minutes
In what disease conditions is silver sulfadiazine commonly used?
Burns, wounds, otically
Discuss alcohol as a disinfectant, including its categorization (low, intermediate, high), relative onset, and types of alcohol (isopropyl, ethyl, and methyl alcohol) and concentration percentages for best efficacy.
Ethanol or isopropyl
- low to intermediate: effective against most vegetative bacteria and enveloped viruses –> rapid killing of susceptible organisms
- 70% concentration is optimal, presence of water enhances killing action –> good skin antiseptic with cleaning benefit (hair must be removed and alcohol must evaporate)
- function: denature proteins
Chlorhexadine
Good against gram-pos, variable activity against fungi and viruses, NO activity against spores!
- low level disinfectant
- gluconate (scrub) or diacetate (solution)
- function: disrupts cell membrane
- maintains activity in organic matter! looses activity in anionic detergents
Benzoyl peroxide
Active against gram pos bacteria
- too toxic for tissues!
- used on pyodermas (follicular flushing)
- the most repository skin antiseptic (only OTC that has an antibacterial effect)
- drying or irritation if overused
- shampoo or lotions up to 10% (2.5% commonly used)
Hydrogen peroxide
Used to clean intact skin, too toxic to tissues for use as an antiseptic!!
- 3% solution
EDTA
Chelates cations, damages bacterial cell wall creating a synergistic effect with antibiotics
- used in otitis externa, multi-resistant bladder infections as infusion, wounds, and fistulas
Povidone iodine
Complexed iodine compounds (iodophores)
- bound to high MW carrier
- increased solubility, improved wetting properties –> less toxic to tissues and the only iodine recommended for use in wounds!!
- scrub used as skin prep
- 0.1-1% used to lavage wounds
- least residual activity of the antiseptics
- bacterial resistance to iodophores has been found, alternate antiseptics when doing daily lavages
What are the 9 common disinfectant mistakes?
- eyeballing disinfectant solution mixtures
- failing to reach designated contact time
- confusing sanitized with disinfected
- not knowing the shelf life of the disinfectant being used
- topping off diluted disinfectant bottles, rather than starting each time with a cleaned bottle and fresh batch
- mixing cleaning chemicals
- spraying a surface and then wiping it with a dry cloth
- not giving or receiving product-specific training to vet team members
- not getting buy-in from team members on a switch to a new product
