Antiseptics and disinfectants

Definition
Selection
Table for the use of antiseptics and disinfectants
Preparation and storage of antiseptic solutions
Preparation and use of disinfectant solutions for floors and surfaces
Preparation and use of disinfectant solutions for medical material

Definition

Antiseptics are products used for the disinfection (asepsis) of living tissues (skin, wounds, mucosa.).

Disinfectants are products used for the disinfection of objects and surfaces (floors, tables.).

Certain products can be used both as antiseptic and as disinfectant (e.g. polyvidone iodine, chloramine T), but, unfortunately, the perfect product, which is cheap, effective for all bacteria, stable, easy to transport and suitable for use both on living tissue and objects, does not exist - at least not yet.

Selection

We can nevertheless suggest a restricted list of products that meet all the demands of medical facilities:

- normal soap,
- tosylchloramide sodium (= chloramine T),
- chlorhexidine (or preferably chlorhexidine + cetrimide),
- polyvidone iodine,
- gentian violet,
and for floors and surfaces:
- a soapy solution of cresol (= Lysol) or preferably a product that generates chlorine like calcium hypochlorite (HTH), bleach, sodium dichloro-isocyanurate (= NaDCC) or even chloramine T.

In the chapter "Drugs for external use and disinfectants", the descriptions for each product give details on the use of these products. Other widely-used products are also described.

Finally, some notes on particular products:

- Alcohols (ethanol and isopropanol)

Good disinfectants at 60-70° (60-70%) for objects or intact skin (more effective at 60-70° than at 90-95°), but:

They are not good for wounds because they are painful and slow the healing process.

They are expensive both to buy and to transport (they require special packing for air transport). Moreover, the purchase, transport and importation of ethanol often require complicated administrative procedures.

They can be advantageously replaced by polyvidone iodine.

- Chloroxylenol (Dettol (R))

An efficient but expensive product which can be used as an antiseptic (0.25% chloroxylenol solution) and disinfectant (see "soapy solution of cresol").

Can be of interest if locally available.

- Eosin

Antiseptic with limited effectiveness, but useful as a drying agent. Its aqueous solutions are easily contaminated by pathogenic bacteria.

Can be replaced by gentian violet.

- Hydrogen peroxide (hydroperoxide)

Very useful for certain indications (e.g. dirty wounds), but very hard to preserve in diluted and ready-to-use form. Concentrated hydrogen peroxide is dangerous to transport and handle.

- Hexachlorophene

Antiseptic with limited effectiveness and toxic for the central nervous system. Usage not advised.

- Mercury derivatives: e.g. Phenylmercury (Merfen (R)), Mercuresceine (Merbromine, Mercurochrome (R), Mercurobutol (Mercryl (R)), Thiomersal (Merthiolate (R), Timerosal (R))
Antiseptics with limited effectiveness in aqueous solutions (mercurosceine has very little effect).

Toxic for the kidneys and the central nervous system, often cause allergies and pollute the environment.

Forbid their use.

- Ether

Often wrongly used as an antiseptic. It has no disinfecting properties, but degreases the skin and removes sticky residues of elastoplast and similar dressings.

Table for the use of antiseptics and disinfectants

Preparation and storage

Although it may seem paradoxical, the aqueous solutions of antiseptics can become contaminated when handled and turn into bacterial cultures, especially Pseudomonas aeruginosa (pyocyanic).

To avoid this, the following precautions must be taken:

- Make all aqueous dilutions with either:

· drinking water,
· water filtered by a well-maintained candle type filter,
· boiled water (previously filtered through cotton if it is turbid).

- RENEW ALL AQUEOUS SOLUTIONS AT THE LAST ONCE A WEEK.
- Only prepare small amounts at a time to avoid wastage and the temptation to keep and use expired solutions.
- Never mix the fresh solution with the expired one (wash and dry the bottle before each refill).
- Do not use a cork.

On the bottles, mark the name and concentration of products.

Preparation and use of disinfectant solutions for floors and surfaces

- The dilutions of Lysol (or similar) and the dilutions of chlorinated disinfectants must be prepared just before use. Make the dilutions with clear water.
- The chlorinated disinfectants are only fully effective on clean surfaces. The area must be cleaned before they are applied. Nevertheless, they have the advantage of clearly proven antiviral activity and are relatively cheap.

Preparation and use of disinfectant solutions for medical material

Soaking clean material for 15 minutes in the disinfectant solutions indicated in the table below gives a very effective disinfection for bacteria in vegetative forms and for viruses (including the AIDS and hepatitis B virus). However, the bacterial spores are generally not destroyed (e.g. tetanus spores).

Sterilization (elimination of all bacteria, including the spores) can only be obtained with an autoclave or a good electric hot air sterilizer. Sterilization is obligatory for all materials that come in contact with sterile parts of the body (equipment for punctures, injections and surgery.)

Soaking in strong disinfectant solutions can sometimes be an alternative to sterilization when the latter is impossible. However, in that case, boiling is still the best approach. The effectiveness of chemical disinfection can be impaired by an error in the dilution or the degradation of the disinfectant resulting from poor storage conditions.

Chemical disinfection is never recommended for sterilizing syringes and needles.

Powerful disinfectants suitablefor use on medical material

CLEANING OF DIRTY EQUIPEMENT

Reusable equipment must be carefully cleaned before sterilization or disinfection.

The cleaning is carried out with water and soap (or another detergent).

To facilitate cleaning, the material should be soaked in water immediately after use, so soiled parts will not dry. Half an hour before cleaning the equipment, a disinfectant can be added to this water for an initial decontamination (e.g. chloramine 20 g/litre, Lysol 50 g/litre). Soaking for too long or with too high a concentration of disinfectant can cause corrosion of metal instruments.

After cleaning, the equipment must be carefully rinsed with clean water and then dried.