PrevMed1-Environment Disinfect

  1. Define disinfection.
    • destruction of pathogenic organisms on inanimate surfaces¬†
    • [different from antisepsis (destroy organisms on living tissues) and sterilization (destroy all forms of microbial life, including endospores)]
  2. What are key components to cleaning and disinfection? (4)
    • must be clean and dry before being disinfected (disinfectants are not good in the face of organic debris, make sure it's dry or else you will dilute the disinfectant when you apply it)
    • cleaning: removal of visible matter with soap
    • disinfection: application of chemical or other procedure to kill most of the remaining microbes
    • disinfection efficacy depends on product, dilution/ conc, and contact time
  3. If you must have wood in a stall or facility, how should to handle this to ensure best possible disinfecting surface?
    seal wood with a marine epoxy to prevent pathogens from establishing in the porous wood
  4. What are important pathogen factors affecting disinfection? (3)
    • susceptibility and stability of the pathogen
    • abundance of the pathogen
  5. What are important  disinfectant factors influencing disinfection? (4)
    • spectrum
    • concentration
    • contact time
    • stability
  6. What are important surface factors influencing disinfection? (2)
    • texture/ material
    • organic load
  7. What is the disinfectant label based on, and what are the types of labels?
    • determine by in vitro efficacy against S. aureus, Salmonella, and Pseudomonas
    • "Limited efficacy"= Gram + or -
    • "General Purpose", "Broad spectrum"= Gram + AND -
    • "Hospital or medical environment"= Gram + and - and nosocomial
  8. What are the advantages and disadvantages of aldehydes?
    • A: broad spectrum, sterilization
    • D: carcinogenic, irritation, PPE required
  9. What are the advantages and disadvantages of halogen disinfectants (bleach)?
    • A: broad spectrum (even non-enveloped virus), low cost
    • D: no cleaning properties, inactivated by sunlight and organic material, corrosive, damages rubber, irritation; dangerous if mixed with acid or ammonia
  10. What is not a good disinfectant for a foot bath and why?
    • chlorine bleach
    • quickly inactivated, inactivated by sunlight and organic material; must be used fresh
  11. What are the advantages and disadvantages of oxidizing agent disinfectants (Virkon)?
    • A: broad spectrum, some detergent activity, long shelf life once mixed
    • D: corrosive, expensive
  12. What disinfectants are not good for iso areas and why not?
    • quaternary ammonium (Roccal), Substituted phenols (lysol)
    • because they don't kill non-enveloped viruses
  13. What are the advantages and disadvantages of substituted phenol disinfectants (Lysol)?
    • A: broad spectrum, active in hard water, active in presence of some organic material, residual
    • D: limited activity against non-enveloped viruses, skin irritation, toxicity
  14. What are the advantages and disadvantages of quaternary ammonium disinfectants (Roccal)?
    • A: reasonable spectrum, low cost, some detergent activity
    • D: not effective against non-enveloped viruses, inactivated by many soaps
  15. What are some FMD-specific disinfectants?
    • [remember FMD is a non-enveloped virus]
    • alkalis- sodium hydroxide, sodium carbonate
    • acids- hydrochloric acid, citric acid
    • effective with heavy organic material, which is important b/c this is found on farms
  16. Describe the preliminary disinfection step of a decontamination protocol. (4)
    • immediately after confirmation of outbreak then continuously until initial clean up
    • reduce amount and distribution of pathogen immediately
    • all contaminated areas
    • dispose materials not suitable for disinfection and contaminated feed
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PrevMed1-Environment Disinfect
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