Part 1 – Introduction

Welcome, everyone, to this series of lessons focused on biorisk management. In this lesson, we shall examine the concepts of decontamination and sterilization as it relates to infection control. It is imperative to understand how to ascertain whether all items in your laboratory are being effectively decontaminated and whether the intended materials are being adequately sterilized. Furthermore, we will explore the methodologies and techniques necessary for executing these procedures in the laboratory setting.

To start, let us clarify some definitions, as sterilization and disinfection are not synonymous. We will begin with the term sterilization. This refers to the act or process—whether physical or chemical—that destroys or eliminates all forms of life, particularly microorganisms. The definition of sterilization is absolute; an item is classified as either sterile or not sterile. Sterilization is a definitive process, possessing a clear definition and endpoint. In contrast, disinfection is a less lethal process than sterilization. It involves the elimination of nearly all recognizable pathogenic microorganisms, although it may not eradicate all of them. For instance, bacterial spores may survive, while other vegetative bacteria may be eliminated. Thus, sterilization represents a comprehensive and exhaustive process, whereas disinfection is comparatively less destructive.

Another term frequently utilized is decontamination, which differs from both sterilization and disinfection. Decontamination refers to the process of removing contamination, thereby rendering an area, item, or material safe for handling. This process results in the item being rendered reasonably free from the risk of disease transmission, which is less destructive to microorganisms than disinfection and certainly less so than sterilization. Lastly, we consider antiseptics, defined as a substance that prevents or inhibits the growth or action of microbes, either by obstructing their activity or by destroying them. The term originates from the Latin roots “septic,” indicating the presence of disease-causing organisms, and “anti,” signifying removal or cessation. Antisepsis thus relates to the elimination or inhibition of pathogenic microorganisms.

Adhering to good biosafety practices and procedures necessitates the utilization of sterilization, decontamination, and disinfection within the laboratory to ensure the decontamination of instruments and work surfaces. It is crucial to employ an appropriate disinfectant tailored to the specific agent being utilized, as various agents respond differently to disinfectants. One must select the correct disinfectant for the respective agent in use. Disinfection should be conducted after any spills and after each project or workday. Additionally, ensure that equipment is decontaminated before its removal from the laboratory to preclude the risk of contaminating service personnel with potentially contaminated materials. Finally, it is essential to decontaminate all potentially infectious materials before disposal, encompassing solid objects, equipment, sharps, cultures, and any items that have come into contact with pathogenic organisms or have been contaminated during laboratory activities.

Personnel decontamination is equally vital. It is necessary to wash hands following the handling of infectious materials or animals, after the removal of gloves, and before exiting the laboratory. Washing hands with soap and water serves as an effective antiseptic, as the physical action of rubbing the hands together, combined with soap, facilitates the removal of microbes and oils from the skin. Therefore, the practice of thoroughly washing one’s hands after working in the laboratory is the most critical personal decontamination procedure one can undertake.

Laboratories generate a considerable amount of infectious biological waste during research activities. This waste encompasses cultures, stocks, isolates, pipettes, tips, syringes, and sharps—essentially any items that may have come into contact with microbiological agents. Furthermore, various materials within the laboratory may have been subjected to spills or splashes, necessitating careful consideration for decontamination. However, not all items in the laboratory require the same level of decontamination and disinfection. It is imperative to assess what requires decontamination and to what extent, based on a thorough risk assessment.