diphenyl ether; MOA microbial cell wall disruption
Per Tob ch 14, MOA involves disordering protein structure, blocking protein synthesis and altering the cell membrane; Per Fossum 4th ed, MOA iodination and oxidation of essential molecules; Penetration of the cell wall and oxidation and replacement of intracellular molecules with free iodine. Iodophores are solutions of iodine with a surfactant or stabilizing agent that liberates free iodine.
Spectrum of Povidone Iodine; and at what concentrations are they lethal to fibroblasts?
One of the most common iodophors. Rapid efficacy in killing bacteria, spores, viruses and fungi - broad spectrum - lethal to canine fibroblasts at concentrations a 0.5% or greater, but concentrations of 1% or greater are necessary for bactericidal activity. Concentrations of 0.001% maintained bacterial toxicity while sparing human fibroblasts
Cationic bisbiguanide chlorhexidine commonly used in chlorhexidine gluconate (scrub) or chlorhexidine diacetate (solution). Bacteriostatic at lower concentrations by interfering with the cell membrane and causing leakage of intracellular contents. At higher concentraions- a bactericidal effect. Surgical scrub formulations are recommended 2% to 4%, whereas wound treatment formulations are normally .05% or less -
Bactericidal effects; denaturation, metabolic interruption, and cell lysis
- most effective concentration reported to be 60% to 70% - Isopropyl alcohol (50-70%) is an alternative to ethyl alcohol (70%) with greater bactericidal efficacy but is less virucidal activity
disruption of microbial cell walls and leakage of cell proteins; less effective than iodophors and chlorhexidines and their use is not recommened per Tob ch 14.
disruption of cell wall and leakage of proteins; not discussed in Tob Ch 14
MOA Aldehydes (Glutaraldehyde)
protein and nucleic acid alkylation; less effective than iodophors and chlorhexidines and their use is not recommened per Tob ch 14.
acts by microbial cell wall disruption and exzyme inactivation; less effective than iodophors and chlorhexidines and their use is not recommened per Tob ch 14.
The current literature strongly suggests that CHG is superior to PVI for preoperative antisepsis for patients. One study found a greater than ___% reduction in total surgical site infection among patients undergoing clean-contaminated surgery who had received a single chlorhexidine-alcohol scrub (Darouiche et al, 2010)
How much skin contact time do Iodophors require to allow release of free iodine?
What condition has been reported after contact of chlorhexidine wth the eye?
What 4 factors affect ethylene oxide activity?
1 - gas concentration 2 - temperature 3 - exposure time 4 - humidity
What affect does ethylene oxide gas concentration have on exposure time?
double concentraion, decrease time by half
What affect does temperature have on ethylene oxide activity?
activity doubles with every 10 degree Celcius increase
What affect does ethylene oxide activity have on exposure time?
48 minutes to several hours
Optimum humidity for ethylene oxide sterilization?
optimum 40% (to 80%, minimum is 35%)
EtO gas concentration
450 - 1200 mg/L
84 - 149 degrees F
45% to 85%
2 - 5 hours followed by aeration
What does increasing the temperature do to the sterilization time?
Increasing the temperature to 55C reduces the exposure time to 4 hours or less
What is another technique to address sterilization of heat-sensitive items?
MOA Ozone sterilization
ozone molocule O3 readily oxidizes other molecules to cause destruction of microorganisms - advantage : lack of toxic residues
MOA Plasma Sterilization
uses electromagnetic energy to create a plasma phase from a vapor of hydrogen peroxide, oxygen, or peracetic acid/hydrogen peroxide mixture - contain free radicals that deactivate cellular process
What are plasma sterilizers useful for?
moisture or heat sensitive items
Advantage of plasma sterilizers
short cycle time, ability to sterilize a wide range of heat or moisture sensitive items. lack of environmentally toxic residues
What is the most commonly used cold sterilization chemical?
What does Gluteraldehyde do?
efficacy against bacterial spores with prolonged exposure
What liquid chemical germicide is superior to Gluteraldehyde?