Effets des biocides sur la résistance aux antibiotiques
2. What are the main uses of biocides?
- 2.1 What are the main applications for biocides in health care?
- 2.2 In which consumer products are biocides used?
- 2.3 How are biocides used in the food industry?
- 2.4 How are biocides used in animal husbandry and in products of animal origin?
- 2.5 How are biocides used in water treatment and industrial applications?
2.1 What are the main applications for biocides in health care?
The proper use of
biocides is crucial in
preventing and controlling the spread of
infectious diseases in
hospitals and other health facilities. Biocides are used to
decontaminate the skin of patients and health professionals, any
surfaces that could harbour
bacteria, and any
instruments in contact with patients. Biocides are also used as
antiseptics to treat
mucous membranes and
classified as low, medium or high-level disinfectants, depending
on how many types of
micro-organisms they kill.
High-level disinfectants that are applied for long periods of
time can inactivate all micro-organisms and are called chemical
Table 3: Biocides approved by US-FDA for health care settings,
or registered by the US-EPA
The level of disinfection in medical facilities usually
depends on the degree of
- Surgical instruments, needles, catheters and any other
devices that enter the patient’s
tissues must be sterile.
The best way to achieve this is to use steam under pressure
but instruments that cannot be heated need to be treated
- The risk of
infection from devices
that come into contact with
mucous membranes or
damaged skin, such as endoscopes and tubes used in
anaesthesia, is not as high but these should still be
sterilized to provide the widest margin of safety.
- Stethoscopes, bedpans, blood-pressure cuffs and
similar devices pose little risk of transmitting infections
and can be treated with low-level
Biocides are used to
disinfect these as well as surfaces that are near patients
such as floors, walls, tables, bedrails and
There is evidence that surfaces can act as a source of
contamination and may contribute to the spread of infections
such as MRSA and Clostridium difficile. However, the
routine use of biocides to
treat these surfaces is controversial.
Antimicrobial wipes are
increasingly common in hospitals but their inappropriate use,
for instance cleaning several surfaces with the same wipe, can
cause problems. There are new products such as shower curtains
and trolleys that incorporate biocides in their surfaces. In
some health facilities they have reintroduced the use of metals
for surfaces that are touched frequently hoping to reduce the
spread of infections, but it is difficult to evaluate precisely
if these have had any effects.
Biocides are also used to
kill or reduce the numbers of harmful
micro-organisms on the skin
of patients and medical staff. The most common method of
disinfecting the hands of medical staff is the use of
because they are easy to use and effective. In addition to
quaternary ammonium compounds
and triclosan, and some
preparations combine several substances.
Table 4: Commonly used skin disinfectants and antiseptics
2.2 In which consumer products are biocides used?
Biocides are for instance included in cleaning
Credit: Sanja Gjenero
Many consumer products contain
biocides but the major
sources of exposure in homes are the regular use of cosmetics
and wipes, cleaning products, some toothpastes, laundry
disinfectants and general
Biocides are added to
cosmetics and personal care products to prevent
growing on them. In the EU, the use of 57 different chemicals is
allowed for this purpose. Besides these chemicals, cosmetics
often contain other non-regulated
Many of the substances that are added to household products to
improve their properties also kill
bacteria. This is for
instance the case of
surfactants that are
included in detergents to
decrease the surface tension of water enabling the detergent to
better penetrate and loosen dirt. Cleaning products and laundry
disinfectants but the use
of these substances in household products is not regulated.
Surfaces coated with
biocides have been
developed recently. These biocide-treated surfaces include
several active ingredients
such as triclosan and
The biocide triclosan is
used in consumer products and textiles, notably in cosmetics,
toothpastes and products for dental hygiene, and in deodorants,
but also in cleaning products, paints, plastic products and in
clothes to avoid unpleasant odours produced by decomposition of
2.3 How are biocides used in the food industry?
Biocides are widely used
in the food industry as
disinfectants and food
They treat production plants, processing areas and food
containers to control the microbial growth in food and drinks.
They are also commonly used to disinfect equipment, containers,
surfaces or pipes associated with the production, transport and
storage of food or drink, including drinking water. In the EU,
the use of disinfectants in
the food-processing industry and in the treatment of drinking
water is regulated.
Drinking water is treated with
biocides to eliminate any
harmful micro-organisms at
the water works and in the distribution system to ensure that
the water that reaches the consumer is fit to drink. For the
last century, chlorine has
been added to the water before it enters the waterworks for
treatment. Ozone and
chlorine-dioxide are now more commonly used for that purpose to
avoid the creation of unwanted by-products. In some countries,
disinfection in the distribution system is always performed with
Biocides are added as
preservatives to foodstuffs
to prolong their shelf-life by protecting them against
deterioration caused by
micro-organisms. They are
considered as food additives and their use in the EU is
2.4 How are biocides used in animal husbandry and in products of animal origin?
Biocides are used when breeding and raising livestock.
Credit: Mark Foreman
Proper cleaning and disinfection play a vital role in
protecting food animals from diseases that they could pass on to
humans. Although the use of
biocides in breeding and
raising livestock is regulated in each Member State, there are
no exact data on the amounts of biocides used. It appears that
each farm only uses few types of
disinfectants and the same
brand may be used for extended periods of time.
Biocides have four main
uses in animal husbandry:
- Cleaning and disinfecting farm buildings, particularly
between batches of animals as well as decontaminating ponds
and equipment in fish farming.
- Creating barriers against
bacteria, such as foot
dips outside animal houses, and disinfecting vehicles and
materials during outbreaks of
- Preventing infections through direct application to
animal skin, for instance to clean the udders of animals
used for milk production
- Preserving specific products such as eggs or
Table 5: Major biocides used in veterinary medicine and animal husbandry
Moreover, biocides are
used to protect animal feed from deterioration by
micro-organisms. They are
considered as food additives and they are not allowed without a
Chemicals used in animal production could leave residues in
milk, meat or eggs. Therefore, before
allowed, they are tested to see if they are safe. This includes
an assessment of the possible effects of these residues on the
bacteria that naturally
live in the human gut.
Biocides can be used to
kill bacteria on the
surface of animal products such as poultry and other carcasses.
This practice is not authorized in the EU so far.
2.5 How are biocides used in water treatment and industrial applications?
Biocides are used in
industry and in the treatment of drinking water and wastewater,
but the quantities involved are not known.
Many wastewater treatment plants, especially those near the
sea, include a final step of disinfection with
chlorine. However, this
practice is being increasingly questioned because the
by-products are toxic to sea
animals and because it can lead to false-negative tests, where
water samples appear clean but in fact contain
viruses and other
survive chlorine and may cause outbreaks that can affect
swimmers or consumers of sea-food.
intensively used in cooling towers since some harmful
bacteria such as
otherwise thrive in the warm water and be spread through air by
tiny water droplets
(aerosols) released by the
cooling tower. After use, these
biocides may reach the
environment either as aerosols or in the wastewater.
Biocides are increasingly
added to building materials,
antimicrobial surfaces and
other products, to stop them becoming encrusted with
moulds or other
micro-organisms; but the
quantities used are unknown. Some of these surfaces release
small amounts of biocide progressively into the environment and
this could kill certain types of
bacteria in the immediate
vicinity, leaving only
Therefore, biocide aerosols
could have a role in emerging
resistance of bacteria to
biocides or antibiotics,
but this point has not yet been investigated.