Chapter 11 - Disinfectants and Antiseptics Flashcards
Disinfection
Destruction of pathogenic microorganisms
Hospital associated infection
Originating within the teaching hospital
Nosocomial Infections
Infections acquired during a period of hospitalization - they are especially hard to control.
Biofilm
Generated by bacteria when they attach to a surface and develop a glycocalyx (material made of protein, DNA, and polysaccharides) “shell” around themselves in which the bacteria can proliferate protected from the disinfecting agents
List some common sites for creation of biofilm or nosocomial infections
Urinary tract Respiratory tract Surgical sites Wounds IV catheter insertion sites
Antiseptics
Chemical agents that kill or prevent growth of microorganisms on living tissues
Disinfectants
Chemical agents that kill or prevent the growth of microorganisms on inanimate objects
Vegetative bacteria
Actively growing bacteria not in a spore state
Enveloped viruses
Viruses surrounded by a thin, phospholipid/protein envelope used to enter a host cell
High-level, Intermediate-level, Low-level disinfectants
Designation that generally refers to the ability of the disinfectant to kill pathogens with different levels of susceptibility
Does the envelope around an enveloped virus protect the virus?
No - it is an essential component of the virus and is readily disrupted by detergents and disinfectants
List some enveloped viruses
Canine distemper virus Feline herpes virus Rabies Influenza virus Poxviruses
Nonenveloped viruses
“naked” virus core without a surrounding lipid envelope
Spore form
Refractile, oval body formed within bacteria regarded as a resting stage during the life history of the cell - characterized by resistance to environmental change
Protozoal oocysts
Cyst containing the zygote of the protozoan parasite
Sanitizers
Chemical agents that reduce the number of microorganisms to a “safe” level without eliminating all microorganisms
Sterilizers
Chemicals or other agents that destroy all microorganisms
Can sterilization be achieved on living things?
No - only inanimate objects
Germicides
Any chemical agent that kills microorganisms (this includes viruses, bacteria, protozoa, and fungi) so they are not used in veterinary medicine because it is too nonspecific
Bactericidal
Chemical kills bacteria
Virucidal
Chemical kills viruses
Fungicidal
Chemical kills fungi
Protozoacidal
Chemical kills protozoa
Sporicidal
Chemical kills microbial spores when it is in its resistant or dormant state
Can disinfectants be microbiostatic?
NO. They need to microbicidal because inanimate objects do not have an immune system to eliminate organisms not killed
What microorganisms can live in two forms: Vegetative and spore forms?
Bacteria
Fungi
When a microorganism switches from spore form to vegetative form what happens?
Spore forms survive in a dormant state for years to decades so that under appropriate growing conditions they can switch back to vegetative form and begin multiplying again
What is an absolutely necessary step in disinfection that is often ignored?
Surfaces must be thoroughly cleaned with soap and rinsed to remove organic material and debris and allowed to dry before application of disinfectant
Cleansers
Detergents or surfactants - used before application of disinfectant to remove organic material
Cleansers are classified into 3 groups
Anionic
Cationic
Nonionic
Solubilizing
Dissolving
What are the 5 characteristics of an ideal disinfecting agent
1) Broad spectrum of antimicrobial activity
2) Nonirritating and nontoxic to animal/human tissue
3) Easily applied to inanimate objects and without causing corrosion or stains
4) Stable and not easily inactivated
5) Inexpensive
Alcohols
Most commonly used as part of aseptic technique (surgical sites)
Acts by solubilizing lipid membranes and by denaturing proteins
At what concentrations are alcohols most effective at?
70-90%
Alcohols above 95% do not contain enough water needed to effectively denature the proteins of the pathogen and produce disinfection
What are the 2 alcohols commonly used?
Isopropyl
Ethyl
Coagulum
Applying alcohol to open wounds - which usually contain serum exudate (rich in protein) - alcohol denatures the structure of this protein, causing it to form a superficial barrier which may seal in or protect underlying bacteria, preventing topical disinfectants from reaching the organisms- infection could then spread to underlying tissues
Halogens (chlorine compounds)
Intermediate-level disinfectant - can kill vegetative forms of bacteria, algae, fungi and both enveloped and nonenveloped viruses
What is Halogens (chlorine compounds) mechanism of action?
Chlorine ions liberated from the disinfecting compounds kill pathogens by denaturing protein structure and chemically inactivating essential enzyme systems needed by the pathogen
Halogens (iodine compounds/iodophors)
Most commonly used as topical antiseptics before surgical procedures or for aseptic disinfection of tissue
What is Halogens (iodine compounds/iodophors) mechanism of action?
Bactericidal, virucidal, fungicidal, and sporicidal because of the free iodine which diffuses into the pathogen cell and disrupts metabolism and protein structure and synthesis
What are halogen iodine compounds known to be topically effective against?
Dermatophytes that cause Ringworm
Halogens (both types) are inactivated by organic material, especially blood, but which compound better maintains its antiseptic activity in the presence of organic material?
Iodine compounds/ Ionophors
Iodophors
Combination of molecular iodine and a carrier molecule that releases the iodine over time, prolonging the antimicrobial activity
Iodophors combined with detergent or nonionic surfactants are commonly known as what?
Surgical scrubs
Why should high levels of iodine be avoided on denuded skin?
Potential for irritation and systemic absorption of iodine
Biguanides
Chlorhexidine, nolvasan, virosan, hibistat
Chlorhexidine
Works by damaging the cell membrane of the pathogen, lysing the cell. One of the most commonly used disinfectant and antiseptic compounds used in vet med
What preparation of chlorhexidine should be avoided for use in animals?
Otic solution - Ototoxic if exposed to the middle ear
Aldehydes
Glutaraldehyde
Glutaraldehyde
High level disinfecting chemical sterilizer with a wide spectrum of activity against bacteria, viruses, fungi, and bacterial spores (chemically related to formaldehyde)
What is Glutataldehyde’s main use?
Disinfecting equipment that cannot be heat sterilized - also widely used to cold-sterilize clinical instruments
Glutaraldehydes mechanism of action
Penetrates biofilm and reach the bacteria, and cause the bacterial colony to detach from the surface of the instrument and be flushed away
What are 2 things that must be maintained to keep glutaraldehyde working appropriately?
1) Must be kept at room temperature
2) pH must be neutral to alkaline
Oxidizing compound (Hydrogen peroxide)
Work primarily by denaturing proteins and lipids of microorganisms (and can potentially have the same effect on mammalian cells)
Why should hydrogen peroxide should not be used on tissue?
Can potentially damage tissue that is healthy or marginally viable
Accelerated Hydrogen peroxide products
Contain lower concentrations of hydrogen peroxide (0.5%), surfactants to break down surface tension of water and allow penetration, wetting agents that allow liquids to spread out over a surface and a chelator
Peroxymonosulfate
Oxidizing agent that has been used to disinfect pools and hot tubs
Potassium Peroxymonosulfate (PPMS)
Trifectant. Mixed with surfactant, organic acids, and buffers in a dry tablet form to be dissolved in water. Virucidal (including nonenveloped) bactericidal, fungicidal - even in the presence of hard water and organic materials
Phenols
Effective against gram-positive bacteria
What common household product is a phenol?
Lysol
What major side effect can occur from ingestion of phenols?
Sever liver damage
Triclosan
Phenol that has been incorporated into a variety of soaps, disinfectants, deodorants, shampoos, medical supplies, and even some plastics to decrease bacterial growth
Quaternary Ammonium Compounds
“Quats” cleansing agents (cationic surfactants) with germicidal activity - used in vet med to disinfect surfaces of floors, walls, and vehicles utilized in livestock and egg-laying operations
Why are quats not used as antiseptic agents?
Active ingredients bind to gauze and cotton commonly used to apply antiseptics - CDC no longer recommends them as antiseptics
What is the major quaternary ammonium compound used in vet med?
Benzalkonium chloride - key ingredient in the disinfectant Roccal D
What are Quats effective against?
Gram-positive bacteria + enveloped viruses
Ethylenediamine tetraacetic acid (EDTA) and Tris buffer
Two products that can be compounded and used together to irrigate ear infections, wounds, or fistulas infected with Pseudomonas
Acetic Acid
0.25% solution to kill Pseudomonas organisms and a variety of other gram positive and negative bacteria. Vinegar solution is primarily acetic acid. Sometimes used for otitis externa
Povidone-Iodine
Most common Iodophor
Sodium hypochlorite
Chlorine compound (NaOCl) found in common inexpensive household bleach and often referred to as its proprietary name Clorox
What occurs if chlorine is mixed with other acidic cleaners?
Generates toxic amounts of chlorine gas
What occurs if chlorine is mixed with ammonia-containing compounds?
Produces a very poisonous gas called Chloramine
