IC6 Chemical Disinfectants 2 Flashcards
Hydrogen peroxide is a peroxygen, used for disinfection, sterilization, and antisepsis. What is hydrogen peroxide MOA?
H2O2 acts as an oxidizing agent by producing hydroxyl free radicals
Radicals induce oxidation of the compound in the outer layer of microorganisms and attack essential cell components including lipids, proteins, and DNA
Hydrogen peroxide is a peroxygen, used for disinfection, sterilization, and antisepsis.
What is its spectrum of activity?
Broad spectrum of activity,
Virus (non-enveloped virus may be resistant)
Bacteria (greater activity against gram-positive than gram-negative)
Yeast
Bacterial spores (higher conc. + longer contact time for sporicidal activity)
Limited activity against mycobacteria
How might resistance towards hydrogen peroxide arise?
Microorganisms (esp biofilms) may produce enzymes:
- Catalase, Peroxidase can decompose/cleave peroxide and incr tolerance of organisms in low H2O2 concentrations
- Specific enzymes that inactivate radicals
What are the properties of Hydrogen Peroxide?
- Clear, colorless liquid, conc. can range from 3-90%
- Most contain stabilizers (e.g., sodium citrate or malonate) to prevent decomposition during storage [*sodium citrate - adjust pH, sequestering agent, blood coagulant]
- No odor or irritation issues
- High concentration can be irritant
- Eye irritant
*Affected/inactivated by organic load (due to peroxidases)
*Incompatible with metal (brass, zinc, copper, nickel/silver)
Accelerated hydrogen peroxide
- stabilized H2O2 so that it can be used for extended periods of time
- has enhanced antibacterial efficacy due to addition of:
- Surfactant
- Disrupt cell outer layer, allow easier/faster entry of H2O2 into cell
- E.g., alkali metal and ammonium salts, alkyl sulphate - Organic acid (chelating agent)
- Chelate/form complex with salts/ions present that may decrease activity or inactivate the radical
- e.g., phosphonic acid, phosphonate - Emulsifier
- disperse product in micelles to keep it stable
- e.g., alkylated diphenyl oxide
Accelerated H2O2 is usually used on ____
Medical or veterinary devices
What are some advantages and disadvantages of accelerated H2O2?
Advantages:
- safe for workers and environment
- nonstaining
- not flammable
Disadvantages
- Short shelf life due to decomposition of H2O2, oxygen can vaporize easily
- Irritant for the eyes (but safer than chlorine)
- not sporicidal at low conc.
- some material incompatibility
What is Peracetic acid MOA?
Peracetic acid is a strong oxidizing agent.
Denatures proteins and enzymes, increases cell wall permeability by disrupting sulfhydryl (-SH) and sulfur (S-S) bonds
Peracetic acid is more potent than H2O2. What is its spectrum of activity?
Broad spectrum of activity,
Sporicidal
Bactericidal
Virucidal (not so much)
Fungicidal
all at low conc. 0.3%
also effective against mycobacteria and algae
What are the advantages of Peracetic acid?
- Decompose to safe and enrivonmentally friendly by products: acetic acid + oxygen + water
- Free from decomposition by peroxidases (unlike H2O2)
- Retain some activity in the presence of organic loads (but still affected by organic residue)
- It can be used as a low temperature liquid sterilant => effective at low conc + low temp
Describe the MOA of vinegar (acetic acid)
Protein precipitation, destroy nucleic acids bond
*often used together with salt
What is the role of salt?
able to induce death by osmosis (draw water out of microorganism cell)
What is the MOA of phenols? *phenols used as antiseptic, disinfectant, preservative
Induce progressive leakage of intracellular constituents, including the release of K+, which is the first index of membrane damage
*work better at lower pH
What is the spectrum of activity of phenols?
Bactericidal
Tuberculocidal
Fungicidal
Some antiviral properties (NOT effective against non-enveloped viruses)
NOT effective against spores
What are the advantages and disadvantages of phenol?
Advantages:
Maintain activity in hard water
Maintain activity in presence of organic matter
Some residual activity after drying
Nonstaining
Not flammable
Can be formulated with soaps to increase penetration
Disadvantages:
Depigmentation of skin
Hyperbilirubinemia in infants
Not compatible with nonionic detergents
What is the MOA of Chloroxylenol? *antiseptic, disinfectant, injectable or ophthalmic antimicrobial
What is its spectrum of activity?
Disrupt microbial cell wall, inactivate cellular enzymes
Bactericidal
Chloroxylenol is realtively nontoxic and nonirritant as an excipient in topical products, however, it is toxic upon ______ or _______
Toxic upon oral consumption or eye contact
Chloroxylenol is often used in combination with edetic acid. Explain the role of edetic acid.
Edetic acid is a chelating agent and sequestering agent. It can form stable complex with trace amount of metal ions that may inactivate the main disinfectant.
What is the MOA of diamidines? *antiseptic, disinfectant
inhibit oxygen uptake, cause leakage of amino acids
What can diamidines be used for?
Bacteriostatic agent for the treatment of wound
*antiseptic
Silver (Ag+) compounds can include silver nitrate and silver sulfadiazine.
Explain the MOA and spectrum of activity of silver ions? *
Silver ions can interact with thiol (sulfhydryl, -SH) groups in enzymes and proteins**, affect microbial plasma, cytoplasmic membrane, DNA and nucleic acids
Antimicrobial, antifungal
SIlver sulfadiazine is used in ____
treatment of burn
Why is the advantage of silver sulfadiazine over silver nitrate?
It is the combi of silver + antibiotic sulfadiazine
Hence it has broader spectrum
It can induce membrane blebs in susceptible bacteria
(Blebs: blister like protrusion filled with serous fluid)
What is mercuric chloride mechanism of action? *disinfectant
Affect microbial peptide synthesis
