Sterilization of products, instruments and environments

Sterilization is understood as the final result of a process that, thanks to the advancement of technology, tends to guarantee the condition in which the survival of microorganisms is highly unlikely. A population of objects is considered sterile if one object in a million is contaminated. A material is defined as sterile if the SAL (sterility safety level) is less than 10−6; that is, when the probability of finding a microorganism is less than one in a million.

The sterilization process is composed of the following phases: transport, decontamination/disinfection, cleansing and washing, rinsing, drying, packaging, sterilization via device (e.g. autoclave), traceability, and finally re-moving the sterilized material to the place from which it was taken.

How it works

The various processes destroy microorganisms by causing the lethal alteration of some of their essential components; in particular, sterilization determines the denaturation of proteins and nucleic acids and the degradation of membrane and cell wall components.

When it must be practiced

Examples of surgical instruments; each of them must be sterilized before the operation

It is necessary to sterilize: According to the law, every article belonging to Category 1 (Critical Articles), that is, all those instruments and objects introduced into the blood or into normally sterile areas of the body or that come into contact with non-intact skin and mucous membranes, require the requirement of sterility. This applies to both surgical and diagnostic and therapeutic activities, including administration sets, syringes, drainage tubes, parenteral solutions, surgical gloves, angiography catheters and all secondary instruments, drapes, gowns that enter the operating field. As regards the articles belonging to Category 2 (Semi-critical Articles), which includes instruments and objects that come into contact with intact mucous membranes, the requirement is desirable sterility, but in most cases a high-level disinfection guarantees, with a reasonable degree of safety, that the article is free from pathogenic microorganisms. Correct conservation of the treated objects is essential to prevent contamination.

Preliminary procedures

In each study, a “space” must be provided for the procedures and storage of sterile material. The “space” must provide for a distinction in flow between dirty and clean material. The behaviors of healthcare workers in the sterilization field are indicated by the procedures (Legislative Decree 81/08 [1]).

By law, the sterilization procedure must be carried out ensuring the safety of the operator; this occurs with the use of gloves, preferably scratch-proof, protective clothing and devices to protect the face from splashes of contaminated substances, such as oro-nasal masks, protective glasses or better protective screens. It is important that the transport from one area to another of the material to be sterilized must take place using grids or basins in order to reduce accidental contact with the operator and the surrounding environment.

Before the actual sterilization, a series of preventive procedures must also be followed. These procedures are intended to protect the operator, reduce the microbial load, and make the sterilizing action more effective. It is not advisable to rinse the instruments before disinfection as this allows the spread of germs, in the sink, on the gown etc.

These procedures can be summarized in 5 points: