Disinfection and Sterilization

Introduction 

Disinfection and sterilisation are two important steps in the process.

The phrase “disinfection” is used to refer to three separate processes (cleaning, disinfection, and sterilisation), thus it would be beneficial to begin by defining our terminology. To put it another way, cleaning merely reduces the quantity of contaminants present while simultaneously eliminating some of the organisms present. Disinfection eliminates the majority of harmful organisms. Sterilization is the process of eliminating or killing all organisms.

In contrast to the production of water for drinking purposes, which just requires cleaning and disinfection, the production of water for higher grade usage, such as water for injection (WFI), which is used in pharmaceutical formulation, necessitates sterilisation.

We tend to analyse all three types of processes with respect to log reductions, whether that be in organisms in general or pathogens in particular, when approaching sterilisation. Kill curves, which show a logarithmic relationship between the “dose” of sterilising agent applied and the percentage of the initial number of organisms present, are frequently used to aid in this analysis. As a substitute for the harder-to-test-for organisms that are also known to be markers of faecal contamination, we frequently use “indicator organisms” such as “colony forming units” or “coliforms.”

Thus, authorities tend to define a specific number of colony forming units (CFUs) and coliforms per unit volume of water when approving new water sources. Even though we are unsure of the microorganisms that these proxies represent, we believe that if these easy to culture organisms survived our method, it is likely that many pathogens did as well.

The decrease in CFUs and coliforms achieved by conventional drinking water treatment techniques prior to the disinfection stage is a 4-log reduction, while the reduction in Cryptosporidium and Giardia cysts is a 2-log reduction. The reduction in viruses is a 2-log reduction.

Following such treatment, conventional disinfection methods such as chlorination result in a 2-log reduction in CFU and coliforms, as well as in viruses, but no reduction in (much smaller) Cryptosporidium cysts. Specifically, this final point is problematic because many regulatory regimes need at least a 3-log reduction in Cryptosporidium levels. It is possible that conventional treatment and chlorination will not be sufficient to ensure safety.

As a point of contrast, sterilising techniques are often described as producing at least a 12-log reduction in the number of organisms present in all sorts of environments.

Sterilization, Disinfection, and Asepsis

Infection control measures include sterilisation, disinfection, and asepsis (cleanliness and hygienic conditions).

Unlike food irradiation, medical sterilisation is a considerably more comprehensive field. When discussing this subject, the phrases sterilisation, disinfection, and asepsis are sometimes used interchangeably. It is important to distinguish between sterility and asepsis. When all viable life forms and their germinative materials such as eggs, spores, and endospores are eliminated (dead), the term “sterility” is used. A creature cannot be “partially sterile,” because sterility is an absolute state of existence. Asepsis is a term that refers to the removal, exclusion, or neutralisation (i.e., rendering nonviable) of only specific types of living forms, while the presence of other organisms may be permitted or even encouraged. To give an example, pasteurisation of food does not eliminate all microorganisms present in the food; rather, it drastically reduces the number of microorganisms present in the food with the intention of storing the pasteurised material in conditions that will keep the low number of microorganisms present, such as refrigeration. Many or all pathogenic bacteria can be neutralised or destroyed during the process of disinfection, which is also known as decontamination. The Centers for Disease Control and Prevention (CDC) defines disinfection as follows: “Unlike sterilisation, disinfection can be performed at a variety of levels.”

• Highly effective disinfectants are chemical sterilants that can be employed for a shorter exposure period than is required for sterilisation to kill all germs with the exception of large numbers or spores of bacteria.
• Mycobacteria (the causative agents of tuberculosis and leprosy), vegetative bacteria, most viruses (including the poliovirus), and the majority of fungi are killed by intermediate-level disinfectants. However, intermediate-level disinfectants do not kill all bacterial spores, which is why they are not recommended for use in public places.
• Low-level disinfectants are effective against the majority of vegetative bacteria, some fungi, and some viruses, including Staphylococcus species, Pseudomonas species, Salmonella species, HIV virus, herpes simplex virus, hepatitis B and C viruses, and many common cold viruses. 

There are hundreds of products that are sterilised or disinfected on a regular basis. Spaulding’s Classification is frequently used to categorise health-care and medical-related objects, which includes: critically important, semi-critically important, and not critically important

Conclusion 

The essential components of hospital infection control efforts are sterilisation and disinfection. Various surgical procedures are performed every day at a number of hospitals. Various health care facilities are doing an increasing number of invasive operations. During various processes, the medical equipment or surgical instrument that comes into contact with the patient’s sterile tissue or mucus membrane is linked to an elevated risk of pathogen introduction into the patient’s body. Furthermore, infection can be transmitted from patient to patient, from patient to health-care professionals, and vice versa, or from the environment to the patient via improperly sterilised or disinfected instruments. To avoid the transmission of these diseases, medical workers, laboratory personnel, and health-care providers should have a better understanding of these approaches.