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PVS antimic week > Disinfectants and sterilisation > Flashcards

Disinfectants and sterilisation Flashcards

1
Q

What are some of the measures involved in disease control?

A
  • Accurate ID of animals
  • Restrictions on movement
  • Lab testing for diagnosis
  • Can allow for specific control vaccination, prophylaxis
  • Infected animal may still shed pathogens into environment so control needs to both treat the animal and also ensure environment in clear
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2
Q

Name a bacteria with a poor survival rate in the environment

A

Mycoplasmas (quite sensitive)

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3
Q

Name a pathogen with an average survival rate and one with a good survival rate

A
  • Average: salmonella, fungal spores

- Good= bacterial endospores (anthrax), Prions

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4
Q

What are the methods of sterilizing media and small equipment?

A
  • Filtration (liquids): using um filters can remove pathogens and ultra filtrations can remove ions
  • Heat inactivation (liquids/ solids): depends on solutions, sugars can caramelise, range of materials can require different temperatures
  • Irradiation: used in medical filed plastics
  • Chemical (surface decontamination)
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5
Q

What is the thermal inactivation range for different pathogens?

A
  • Mycoplamas= 60 deg
  • Canine parvovirus = 100 deg for 1 min
  • Endospores= 121 deg for 15 mins
  • Prions= 132 deg to 4.5 hours
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6
Q

Describe pasteurisation

A
  • does NOT count as sterilisation, because it does NOT KILL all microbes in the food
  • Instead it reduces number of sensitive viable pathogens
  • 90% effective against vegetative (non sporulating) bacteria
  • Involves rapid ehating. cooling of the food
  • Process used because it has less of an effect on the quality of the food item.
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7
Q

What is the definition of disinfection?

A

Destruction of microorganisms by physical or chemical methods on surfaces of objects

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8
Q

What is the definition of antisepsis?

A

Destruction of micro organisms on tissues by chemical which are non toxic and non irritating to the tissue

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9
Q

What are some of the properties that make an ideal chemical disinfectant?

A
  • Broad activity
  • Absence of irritability, tetragenicicty or carcinogenicity
  • Long shelf life
  • Stable
  • Water soluble
  • Active in organic matter (faeces)
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10
Q

Describe the use of alcohols as a disinfectant

A
  • Effective against mycoplasms, Gram + and gram - as well as some efficacy against enveloped viruses, fungal spores and acid fast bacteria
  • Broad action
  • Needs water to work
  • Denatures proteins causing membrane damage
  • Not active against spores
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11
Q

Discuss acids as a disinfectant

A
  • effective against mycoplasms, gram +, gram -, enveloped viruses, fungal spores, bacterial spores
  • Function is related to pH
  • Destroys nucleic acid bonds
  • Can be caustic and have unpleasant fumes, can damage surfaces
  • Viruses can vary is susceptibility, HCl can destroy endospores
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12
Q

Which form of organic acids are able to cross the membrane?

A
  • the associated form (HA)

- ionsised form, then becomes deiionised in the cell

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13
Q

Discuss the use of alkalis as disinfectants

A
  • Action= saponifies lipids in cell membranes/ envelopes. Activity is low but increases with raised temp
  • Effective against Mycoplasma, some efficacy against gram +, gram -, enveloped viruses, fungal spores, acid fast bacteria, bacterial spores, coccidia parasite
  • Caustic and fumes, can cause corrosion.
  • Ammonium hydroxide: effective against coccidial oocysts ( not considered effective against bacteria)
  • Sodium carbonate: hot solution used to disinfect buildings. Not effective for most viruses but is approved for FMDV
  • Calcium oxide (quick lime): used on surface/ the ground. Also used to slow down putrification of buried carcasses.
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14
Q

Discuss teh use of aldehydes as a disinfectant

A
  • V effective against Mycoplasmas, Gram +,gram -, enveloped viruses, some efficacy against non enveloped viruses, fungal spores, bacterial spores, acid fast bacterial, coccidia
  • Highly effective as very reactive compounds
  • Denatures proteins and nucleic acids
  • Active against bacteria (including spores)
  • Non corrosive
  • High toxic, irritating, carcinogenic
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15
Q

Discuss the use of biguanides as a disinfectant

A
  • Effective against mycoplasma, gram+, gram-, enveloped viruses, fungal spores
  • React with cell membranes altering permeability
  • Limited in effectiveness against acid fast/ fungi/ viruses/ spores
  • Inactivated by some anionic detergents
  • Chlorhexidine (hand scrub)
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16
Q

Discuss the use of halogen compounds as a disinfectant

A
  • Effective against mycoplasma, gram+, gram-, enveloped viruses, non enveloped viruses, fungal spores, acid fast, bacterial spores
  • Broad spec
  • 2 groups (Hypochlorite, iodine)
  • Lose potency over time
  • Not as active in organic matter, or sunlight
17
Q

Discuss chlorine compounds as disinfectants?

A
  • Function due to oxidising power, denaturing proteins
  • Use in water treatment and the food industry
  • NEVER MIX WITH ACIDS OR AMMMONIA= WILL CREATE CHLORINE GAS
  • Low conc= vegetative bacteria, fungi, most viruses
  • High conc= active against spores/ more resistant pathogens BUT problems with corrosion
18
Q

Discuss iodine as a disinfectant

A
  • Broad spec= bacteria, fungi, viruses
  • Dentaures proteins
  • Less active than chlorine but more toelrant of organic matter
  • Low water solubility so often dissolved in alcohol
  • Staining is a problem
  • Iodophores: complexes with surfactant the increases solubility and sustained release of iodine
  • Improved activity in presence of organics, dilution of iodophores increases the free iodine activity (common teat dip)
19
Q

Discuss phenolic compounds as a disinfectant

A
  • Broad spec
  • Denaturing proteins
  • Active in hard water and organic material
  • Can cause irritation to skin
  • Environmental problems
  • Can taint food so NOT used in food industry
  • VERY toxic to animals espesh cats
20
Q

What are QACs are what are they used for?

A
  • Quaternary ammonium compounds, sued as a disinfectant
  • Cationic detergent: affects surface of microorganisms
  • Easily inactivated by organic matter and hard water
  • Not effective against non enveloped viruses, mycobacteria, spores
  • Toxic to fish
21
Q

Discuss hydrogen peroxide as a disinfectant

A
  • Non polluting
  • Oxidising agent, reacts with cell components
  • +30%= sporocidal
  • 5-20%= bacteriocidal, virucidal, fungicidal
22
Q

What can be sued instead of formaldehyde?

A

Peroxide vapour

23
Q

What disinfectant is often used in water systems for feeders?

A

Ozone- hyper oxygen species reacts with proteins and nucleic acids
Bacteriacidal, virucidal and sporicidal

PVS antimic week (8 decks)

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