Cleaning of items is essential before disinfection is undertaken and the efficiency also depends on:
1. the nature of microorganisms;
2. the load of microorganisms;
3. the duration of exposure to the agent;
4. the temperature.
Disinfection with low-temperature steam
Typical conditions include exposure to dry saturated steam at a temperature of 730C for a period of 20 minutes at a pressure below atmospheric. This is a useful process for dealing with dirty returns from the operating theatre or clinics which may be contaminated with protein from bodily secretions and microorganisms. Following this method of disinfection the instruments must be cleaned.
Disinfection with boiling water
This utilises soft water at 1000C at normal pressure for 5minutes. Instruments must be thoroughly cleaned before being utilised.
Disinfection with formaldehyde
Formaldehyde gas is a broad-spectrum antimicrobial agent. This process utilises a cabinet which is airtight and circulates gaseous formaldehyde up to 500C.
Disinfection with glutaraldehyde
A 2 per cent solution of glutataldehyde is effective against most bacterial viruses, including hepatitis B and C and HIV, and is particularly useful for the decontamination of flexible endoscopes.
• Thorough cleansing is essential.
• The degree of decontamination is proportional to the time of immersion.
• It is a toxic substance and causes irritant, allergic reactions to the staff, particularly skin reactions, which limits its use.
Safeguards for equipment during sterilisation
Safeguards during sterilisation must include:
• thorough cleaning;
• appropriate packing for the sterilisation of disinfection process in order to avoid reduced penetration of the active agent. This is particularly important in the packing in the autoclave;
• arrangements of articles so that all surfaces are directly exposed to the agent. This includes opening or unlocking jointed instruments and disassembling instruments;
• the use of chemical indicators routinely;
• the interval monitoring of sterilisation process with chemical, thermal and, sometimes, biological indicators;
• the utilisation of flash sterilisation, where a temperature of 1470C is used at a pressure of 40 lb/in.2, is now rare and should only be considered in an emergency situation;
• a careful maintenance plan for all sterilisation processes.
No comments yet.