High Level Disinfection

High-level disinfection (HLD) is a process used to kill or inactivate virtually all microorganisms on medical devices and instruments that come into contact with mucous membranes, but not necessarily bacterial spores.

High-level disinfection is necessary for semi-critical medical devices and instruments that cannot withstand the high temperatures or pressures of sterilization methods. These devices come into contact with intact mucous membranes, such as endoscopes, bronchoscopes, and some surgical instruments.

Low-level disinfection kills most vegetative bacteria, some fungi, and some viruses but does not destroy bacterial spores. High-level disinfection, on the other hand, is more potent and kills all vegetative bacteria, mycobacteria, fungi, and most viruses but not necessarily bacterial spores.

Commonly used high-level disinfectants include glutaraldehyde, ortho-phthalaldehyde (OPA), hydrogen peroxide, peracetic acid, and hydrogen peroxide/peracetic acid combinations. Each has specific advantages and disadvantages, and their effectiveness depends on factors like contact time and concentration.

High-level disinfection is typically achieved through immersion or soaking of the medical devices in the disinfectant solution for a specified amount of time. The process must follow manufacturer guidelines and validated protocols to ensure effectiveness.

High-level disinfection is not as effective as sterilization since it may not kill bacterial spores. However, it is suitable for certain medical devices and instruments that cannot be sterilized.

Critical steps in high-level disinfection include proper cleaning and pre-treatment of the medical devices to remove organic debris, following the manufacturer’s instructions for the disinfectant solution, adhering to the recommended contact time, and ensuring adequate rinsing after disinfection.

High-level disinfectants can be toxic and potentially harmful to humans, so it’s essential to use them in well-ventilated areas, wear appropriate personal protective equipment (PPE), and follow safety guidelines and material safety data sheets (MSDS).

High-level disinfection is not a substitute for sterilization when sterilization is required. It is essential to follow the manufacturer’s instructions and guidelines for each specific medical device or instrument to ensure proper infection control.

High-level disinfection processes should be regularly monitored through chemical indicators and biological indicators (if available) to ensure the effectiveness of the disinfectant solution. Validation should be conducted when new devices or disinfectants are introduced or when process changes occur.