Regulation and standardisation

Regulations and circulars

Not only is aseptic practice a statutory obligation for all medical professions and care establishments, but it is also an ethical obligation. Therefore, the Code of Practice for dental surgeons has provision for obligations concerning hygiene and asepsis :

- article 3-1 requires dentists to make « all appropriate arrangements to avoid the transmission of any pathology that may be present » ;

- article 62 refers to « the installation of equipment for the collection and disposal of clinical waste arising from professional activity and which must conform to current hygiene regulations ».

The practitioner has a duty to undertake aseptic practice for patients in his care in conformity with scientific and established medical data.

Some ministerial circulars or codes of practice addressed to the public hospitals concern the practice of the dental surgery, notably :

- circular DGS/DH n° 98/249 of 20 April 1998, relates to the prevention of transmission of infectious agents from blood and other body fluids whilst patients are being cared for in health establishments. It reminds us of the general hygiene precautions that apply for all patients and all those who care for them. It specifies various recommendations such as those for hand-washing, the wearing of gloves, the necessity to verify that equipment has been properly disinfected and sterilised and that soiled surfaces have been cleaned and decontaminated ;

- circular DGS/5C/DHOS/E2 n° 2001/138 of the 14 March 2001, relates to the precautions to be observed in order to reduce the transmission risks of other transmittable agents (ATNC) and sets out the requirements for new precautions and protocols for hygiene since the emergence of Creutzfeldt-Jakob disease (nvCJD) ;

- the Guide for good practices for the decontamination of medical devices, emanating jointly from the prevention of transmittable diseases section of the Superior Council of French Public Hygiene and of the National Technical Committee for Nosocomial Infections, specifies that an assessment of the risk to the patient must be one of the basic principles for the implementation of disinfection procedures. An assessment of the infection risk and the corresponding level of treatment required, are proposed. According to English authors, three levels of infection risks are described (^{table 1}).

In this description, one notes that most of the treatments undertaken by dentists fall in the « high » level of risk, hence the importance of knowing and carrying out the decontamination and sterilization procedures (^{Rutala, 1993}). In addition, it is the concern of all dentists that they should know the level of risk that they incur on their patients.

Standardisation

Arrangements for the availability disinfection products for the decontamination of medical devices are subject to two legislations.

European legislation

Since 14 June 1998, the European guideline 93/42/CEE indicates that disinfectants of medical devices are themselves medical devices (rule 15, annexe IX). The EC marking of medical devices certifies that they conform to the essential requirements fixed by this guideline. This marking does not dispense with the requirement to verify that the antimicrobial activity of the product used conforms to that required, according to the area of its use.

We must refer to the French legislation and, notably, to that of the Association française de normalisation (Afnor, French Association for Standardisation) to match the required disinfection product to the method of decontamination necessary for medical devices.

Afnor standards

These test standards evaluate, under predetermined conditions, the activity of a product on a given type of micro-organism and so label the product, if the defined standards have been fully achieved.

The concentration of a disinfectant, the length of its contact with the micro-organisms, the temperature during contact and the level of inactivation observed determines its antimicrobial activity. The basic activity of the product is thus defined in terms of its bactericidal, fungicidal, sporocidal and viricidal action.

By using substances that interfere with these functions (e.g. proteins, swabs, hard water) and particular surfaces (e.g. glass, plastic, steel), conditions that approximate more closely to those in actual use can be achieved.

Non-standardised trials

Viricidal activity against HIV

As there is no standard that allows one to measure the activity of a chemical antibacterial agent against HIV, manufacturers use one of the methods recommended by the Pasteur Institute which studies the concentration and the time of action necessary for the product to inactivate 5 log particles of the infectious virus.

Viricidal activity against HBV

No standard exists of the disinfecting efficiency of a product against the hepatitis B virus (HBV). However, two tests are used by manufacturers :

- the MADT test of Kuwert, which assesses changes to the Dane particles by the product ;

- the Frosner method, which determines the inhibition of the surface antigen (HbsAg) by the disinfectant.

Unfortunately, these two tests cannot guarantee total safety against HBV.

Following the comment « active against HIV » or « active against HBV », manufacturers must specify the duration of contact, the concentration and the conditions of the experiment (e.g. the temperature) that were required to cause inactivation of the virus.

Factors to be considered when choosing a disinfectant

For those instruments that cannot be subject to thermal sterilisation, it is necessary to consider two levels of disinfection : decontamination, or predisinfection, and « high-level » disinfection, or final disinfection.

Predisinfection or decontamination

« Predisinfection is the first treatment to be undertaken on materials and soiled objects with the goal of decreasing the population of micro-organisms and to facilitate the subsequent cleaning. » This is the definition that has appeared in the new version of the Afnor Guide for the decontamination, cleaning and the sterilization of surgical instruments.

The objectives of predisinfection are triple :

- to protect staff from all contamination, by the use of antimicrobials and to protect the environment from contaminated substances ;

- to assist the subsequent stages of sterilization or disinfection by reducing the initial contamination :

• by detergent action to reduce soiling,

• by emulsifying proteinaceous substances on medical devices ;

- to facilitate the cleaning of medical devices by dissolution of proteinaceous substances by soaking in a bath.

Predisinfection must involve actions that are both detergent and antimicrobial.

Factors to be considered when choosing a « predisinfectant » (fig. 1)

The product must have both antimicrobial and detergent actions.

It must have a broad spectrum « -cidal » type of action, in accordance with Afnor or European standards :

- standard NF EN 1040 (T 72-152) : bactericidal ;

- standard NF EN 1275 (T 72-202) : fungicidal (contact time, 15 min at 20 °C) ;

- standard NF EN 1276 (T 72-170 or 72-171), spectrum IV : bactericidal in the presence of interfering substances (contact time, 5 min at 20 °C) ;

- standard NF T 72-180 : viricidal (contact time, 15 min at 20 °C) ;

- standard NF T 72-190 : bactericidal, fungicidal and viricidal (method for carrier microorganisms) ;

- standard XP T 72-300 or 72-301 (suspension test).

Equally, it must have an activity on the agents responsible for hepatitis (HBV) and AIDS (HIV).

It must remove stains and prevent the fixing of blood, pus and serum on the materials without damaging the physical or chemical nature of the material. It must not be toxic to users and must be easy to use :

- ready-to-use solution (or to dilute), or in powder form ;

- measured dose by pump, pot or sachet ;

- a time of action that is compatible with repeated use of the instruments (generally 15 min).

Finally, the temperature for its use must be around 20-21 °C.

It is necessary to exclude the use of aldehydes.

It is advisable to display the protocol for predisinfection and cleaning in the sterilisation room (^{fig. 2}).

« High-level » or final decontamination

This involves cold chemical disinfection. The ability of disinfectants to fix proteins means that their use is as a germicide is restricted to devices free of soiling. Also, this disinfection must be undertaken on clean materials. Therefore, instruments will have been predisinfected, rinsed, cleaned and rinsed again.

The product most widely used is glutaraldehyde, which has a very wide spectrum of activity, envelops bacteria, moulds, viruses and spores, but not prions.

At level 1, viricidal assumes soaking in a bath of 2 % glutaraldehyde for 30 minutes.

At level 2, sporicidal, the soaking time is extended to between 1 and 10 hours.

This dilution retains its efficacy for 15 to 30 days (confirm this with the manufacturer's documentation).

The method of use is as follows :

- put on gloves, mask and possibly eye protection (the toxicity of the glutaraldehyde is essentially caused by the fumes that it gives off) ;

- prepare a clean, dry container with lid ;

- dilute the solution immediately prior to use, according to the recommendations of the manufacturer ;

- immerse the clean object for a period of 30 minutes for type 1 disinfection and generally for 2 hours for type 2 disinfection (or according to the recommendations of the manufacturer) ;

- rinse in water appropriate to the level of disinfection that is sought for (e.g. sterile water for surgical instruments).

The disinfected instruments should be used immediately.

Conclusion

It is not sufficient simply to use products that comply with standards. It is imperative to follow the manufacturers' instructions for the use in question, especially the way the product is diluted (if dilution is necessary) and the time for which the instruments should be soaked. Failure to follow this rule will lead to disinfection that is inefficient and illusory.

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BIBLIOGRAPHIE

• Afnor. NF T 72-101. Antiseptiques et désinfectants - Vocabulaire. La Défense : Afnor, 1981.
• Afnor. FD T 72-102. Guide de présentation des normes pour l'utilisateur de désinfectants dans les secteurs hospitalier, médical et dentaire. La Défense : Afnor, 1997.
• Afnor. NF T 72-170. Antiseptiques et désinfectants utilisés à l'état liquide, miscibles à l'eau et neutralisables. Détermination de l'activité bactéricide en présence de substances interférentes de référence (méthode par dilution-neutralisation). La Défense : Afnor, 1988.
• Afnor. NF T 72-171. Antiseptiques et désinfectants utilisés à l'état liquide, miscibles à l'eau. Détermination de l'activité bactéricide en présence de substances interférentes de référence (méthode par filtration sur membranes). La Défense : Afnor, 1988.
• Afnor. NF EN 1040 (indice de classement T 72-152). Antiseptiques et désinfectants chimiques - Activité bactéricide de base - Méthode d'essai et prescriptions (phase 1). La Défense : Afnor, 1997.
• Afnor. NF EN 1275 (indice de classement T 72-202). Antiseptiques et désinfectants chimiques - Activité fongicide de base - Méthode d'essai et prescriptions (phase 1). La Défense : Afnor, 1997.
• Afnor. NF T 72-230. Antiseptiques et désinfectants utilisés à l'état liquide, miscibles à l'eau et neutralisables. Détermination de l'activité sporicide (méthode par dilution-neutralisation). La Défense : Afnor, 1988.
• Afnor. NF T 72-231. Antiseptiques et désinfectants utilisés à l'état liquide, miscibles à l'eau. Détermination de l'activité sporicide (méthode par filtration sur membranes). La Défense : Afnor, 1988.
• Afnor. NF T 72-180. Antiseptiques et désinfectants utilisés à l'état liquide, miscibles à l'eau et neutralisables. Détermination de l'activité virucide vis-à-vis des virus des vertébrés. La Défense : Afnor, 1989.
• Afnor. XP T 72-300 (norme expérimentale). Désinfectants utilisés à l'état liquide, miscibles à l'eau et neutralisables. Détermination de l'efficacité des produits sur divers micro-organismes dans les conditions pratiques d'emploi (essai de suspension par dilution-neutralisation). La Défense : Afnor, 1989.
• Afnor. XP T 72-301 (norme expérimentale). Désinfectants utilisés à l'état liquide, miscibles à l'eau. Détermination de l'efficacité des produits sur divers micro-organismes dans les conditions pratiques d'emploi (essai de suspension par filtration sur membranes). La Défense : Afnor, 1989.
• Rutala WA. Disinfection, sterilisation and waste disposal. In : Wenzel RP ed., Prevention and control of nosocomial infections. Baltimore : Williams & Wilkins, 1993 : 460-495.