Maintenance of practice
22 September 2025 09:41
Preventing spread of disease:
-cleaning + disinfection
-personal hygiene (hands washed frequent, showered daily etc)
-general hygiene
-PPE (scrubs, overalls, gloves)
-vaccination
-ventilation (passive- open windows, active- air conditioning)
-isolation
-barrier nursing (wearing PPE, nursing patients in order (healthy first then
poorly))
-quarantine (coming from elsewhere other countries etc,6 months typically)
-sterilisation
-treatment
-owner compliance (they have to listen to rules)
Microbes and their hosts (cycle):
1. Causative agent (microorganism capable of causing disease)
2. Reservoir (environment, humans, animals)
3. Portal of exit (excretions, secretions, skin, droplets)
4. Mode of transmission (direct contact/indirect contact)
5. Portal of entry (respiratory tract, GI tract, Broken skin, Genitourinary tract)
6. Susceptible host (overcome normal/ natural defences, immunocompromised
patient)
Importance of cleaning:
-all areas of practice assessed for risk according to potential of cross-infection
-standard operating procedures (SOP) should be produced for all areas
-all staff adhere to SOP
-daily and weekly protocols vary between high and low risk areas
-colour coded cleaning equipment
-tasks to be recorded when complete
Hand hygiene:
-Single most effective hygiene measure
Essential VN Page 1
,-using a detergent scrub, using just alcohol (such as sanitiser) is just a hand rub
-alcohol gels convenient but simple disinfection only effective if hands are clean
and dry, soiled hands to be washed first
-hospital acquired infections (nosocomial):
Endogenous- acquired from patients own flora (from the inside)
Exogenous- acquired from healthy carriers, personnel, or equipment (from the
outside)
General hygiene:
-high standards of hygiene to be maintained
-all faeces, urine, vomit and discharge to be removed from a kennel immediately
and patient cleaned thoroughly
-uneaten food to be removed from kennel
-patients mouth nose and eyes to be kept clear at all times
Terminology
Microorganism; living organism too small to be seen by naked eye
Pathogen; a microorganism capable of causing disease
Disinfectant; a chemical that will inhibit or destroy pathogens (NOT bacterial
spores). Used on inanimate objects e.g. floors, kennels
Antiseptic; a chemical that will inhibit or destroy pathogens without damaging
animal cells. Used on living tissue e.g. skin
Detergent; a chemical substance which breaks down grease and dirt. Does not
kill harmful microorganisms. A cleaning agent
Sterilisation; the removal of all microorganisms (including bacterial spores) e.g.
heat, ethylene oxide gas, radiation.
Organic matter; material that is derived from or produced through the biological
activity of a living thing e.g. urine, faeces.
-cide; indicates that a chemical kills a particular type of microorganism e.g.
virucide, fungicide
-stat; the action of a chemical that prevents or inhibits the growth of a
microorganism e.g. bacteriostat
Disinfectant labels
Inert ingredients
Precautionary statement
First aid
Additional precautions
Directions for use
Essential VN Page 2
, Susceptibility of microbes to disinfection
Bacterial spores – hardest to destroy. Disinfectants cannot destroy
Viruses - not as hardy as bacterial spores, quite a few disinfectants will destroy
viruses
Fungi – some forms can be difficult to destroy but are easier to destroy than bacterial
Protozoa – not as hardy as bacterial spores, quite a few disinfectants will destroy
Levels of decontamination
1. Cleaning- physical removal of contamination
Involves use of detergent to remove visible contamination and removes
some microorganisms
2. Disinfection – reduces the number of microorganisms to a level at which they are not
harmful. Spores are not usually destroyed.
Chemical disinfectants have a wide variety of effects on their susceptible
microbes. Some are susceptible to deactivation by organic matter.
3. Sterilisation – removes or destroys all microorganisms including spores
Decontamination
When equipment/surfaces are exposed to chemical agent there is a delay in the
effect. there will be a contact time
If organic matter is present this time can be extended
Microorganisms are then steadily destroyed.
Essential VN Page 3
, Sterilisation
29 September 2025 09:01
Sterilisation = the removal of all microorganisms (including bacterial spores)
Sterilisation renders items safe for contact with tissue and blood without transmission of infection as
long as sterility is maintained
An absolute term, it is either sterile or not
Sterile efficacy
To be effective, sterilisation requires time, contact temperature and, with steam sterilisation, high
pressure. The effectiveness of sterilisation is also highly dependent on a further four factors:
The type of microorganism — certain microorganisms are difficult to destroy. Bacterial spores are
the most resistant of all living organisms and are therefore normally used in the confirmation of
steam sterilisation.
Bioburden — this is the number of microorganisms that may be found on a specific item or in the
environment at a specific time.
The amount and type of organic material remaining on an instrument — all instruments must be
thoroughly cleaned prior to sterilisation. Blood or tissue remaining on instruments acts as a shield to
microorganisms during the sterilisation process.
Design and care of surgical instruments — microorganisms collect in scratches, cracks and crevices
such as the serrated jaws of haemostats. Thorough cleaning and regular inspection of surgical
instruments is therefore essential.
Methods
Cold or chemical
• Ethylene oxide gas
• Chemical
• Irradiation
Heat
• Dry Heat (Hot air Oven)
• Moist heat (Steam under pressure: autoclaves)
Cold sterilisation - Ethylene oxide
• Very effective
• Inactivates DNA, stops cell reproduction
• Effective against bacteria, fungi, viruses and spores. Plastic container with ventilation system
• Polythene liner bag and gas ampoule – bag sealed
• Placed in unit
Essential VN Page 4
22 September 2025 09:41
Preventing spread of disease:
-cleaning + disinfection
-personal hygiene (hands washed frequent, showered daily etc)
-general hygiene
-PPE (scrubs, overalls, gloves)
-vaccination
-ventilation (passive- open windows, active- air conditioning)
-isolation
-barrier nursing (wearing PPE, nursing patients in order (healthy first then
poorly))
-quarantine (coming from elsewhere other countries etc,6 months typically)
-sterilisation
-treatment
-owner compliance (they have to listen to rules)
Microbes and their hosts (cycle):
1. Causative agent (microorganism capable of causing disease)
2. Reservoir (environment, humans, animals)
3. Portal of exit (excretions, secretions, skin, droplets)
4. Mode of transmission (direct contact/indirect contact)
5. Portal of entry (respiratory tract, GI tract, Broken skin, Genitourinary tract)
6. Susceptible host (overcome normal/ natural defences, immunocompromised
patient)
Importance of cleaning:
-all areas of practice assessed for risk according to potential of cross-infection
-standard operating procedures (SOP) should be produced for all areas
-all staff adhere to SOP
-daily and weekly protocols vary between high and low risk areas
-colour coded cleaning equipment
-tasks to be recorded when complete
Hand hygiene:
-Single most effective hygiene measure
Essential VN Page 1
,-using a detergent scrub, using just alcohol (such as sanitiser) is just a hand rub
-alcohol gels convenient but simple disinfection only effective if hands are clean
and dry, soiled hands to be washed first
-hospital acquired infections (nosocomial):
Endogenous- acquired from patients own flora (from the inside)
Exogenous- acquired from healthy carriers, personnel, or equipment (from the
outside)
General hygiene:
-high standards of hygiene to be maintained
-all faeces, urine, vomit and discharge to be removed from a kennel immediately
and patient cleaned thoroughly
-uneaten food to be removed from kennel
-patients mouth nose and eyes to be kept clear at all times
Terminology
Microorganism; living organism too small to be seen by naked eye
Pathogen; a microorganism capable of causing disease
Disinfectant; a chemical that will inhibit or destroy pathogens (NOT bacterial
spores). Used on inanimate objects e.g. floors, kennels
Antiseptic; a chemical that will inhibit or destroy pathogens without damaging
animal cells. Used on living tissue e.g. skin
Detergent; a chemical substance which breaks down grease and dirt. Does not
kill harmful microorganisms. A cleaning agent
Sterilisation; the removal of all microorganisms (including bacterial spores) e.g.
heat, ethylene oxide gas, radiation.
Organic matter; material that is derived from or produced through the biological
activity of a living thing e.g. urine, faeces.
-cide; indicates that a chemical kills a particular type of microorganism e.g.
virucide, fungicide
-stat; the action of a chemical that prevents or inhibits the growth of a
microorganism e.g. bacteriostat
Disinfectant labels
Inert ingredients
Precautionary statement
First aid
Additional precautions
Directions for use
Essential VN Page 2
, Susceptibility of microbes to disinfection
Bacterial spores – hardest to destroy. Disinfectants cannot destroy
Viruses - not as hardy as bacterial spores, quite a few disinfectants will destroy
viruses
Fungi – some forms can be difficult to destroy but are easier to destroy than bacterial
Protozoa – not as hardy as bacterial spores, quite a few disinfectants will destroy
Levels of decontamination
1. Cleaning- physical removal of contamination
Involves use of detergent to remove visible contamination and removes
some microorganisms
2. Disinfection – reduces the number of microorganisms to a level at which they are not
harmful. Spores are not usually destroyed.
Chemical disinfectants have a wide variety of effects on their susceptible
microbes. Some are susceptible to deactivation by organic matter.
3. Sterilisation – removes or destroys all microorganisms including spores
Decontamination
When equipment/surfaces are exposed to chemical agent there is a delay in the
effect. there will be a contact time
If organic matter is present this time can be extended
Microorganisms are then steadily destroyed.
Essential VN Page 3
, Sterilisation
29 September 2025 09:01
Sterilisation = the removal of all microorganisms (including bacterial spores)
Sterilisation renders items safe for contact with tissue and blood without transmission of infection as
long as sterility is maintained
An absolute term, it is either sterile or not
Sterile efficacy
To be effective, sterilisation requires time, contact temperature and, with steam sterilisation, high
pressure. The effectiveness of sterilisation is also highly dependent on a further four factors:
The type of microorganism — certain microorganisms are difficult to destroy. Bacterial spores are
the most resistant of all living organisms and are therefore normally used in the confirmation of
steam sterilisation.
Bioburden — this is the number of microorganisms that may be found on a specific item or in the
environment at a specific time.
The amount and type of organic material remaining on an instrument — all instruments must be
thoroughly cleaned prior to sterilisation. Blood or tissue remaining on instruments acts as a shield to
microorganisms during the sterilisation process.
Design and care of surgical instruments — microorganisms collect in scratches, cracks and crevices
such as the serrated jaws of haemostats. Thorough cleaning and regular inspection of surgical
instruments is therefore essential.
Methods
Cold or chemical
• Ethylene oxide gas
• Chemical
• Irradiation
Heat
• Dry Heat (Hot air Oven)
• Moist heat (Steam under pressure: autoclaves)
Cold sterilisation - Ethylene oxide
• Very effective
• Inactivates DNA, stops cell reproduction
• Effective against bacteria, fungi, viruses and spores. Plastic container with ventilation system
• Polythene liner bag and gas ampoule – bag sealed
• Placed in unit
Essential VN Page 4
