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Good Microbiological Practices and Procedures (GMPP) 4: surface decontamination — Transcript

by World Health Organization (WHO) · 2,483 words · 412 segments · language en · Watch on YouTube

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0:04in the laboratory
0:06there are many surfaces and pieces of
0:08equipment that can become contaminated
0:10by biological agents or other hazardous
0:14materials decontamination is required to
0:19reduce the risk of infection or harm
0:22disinfectants which are chemicals which
0:25can kill or neutralize biological agents
0:27are often used for surface
0:29decontamination the choice of
0:32disinfectant it's concentration and
0:35contact time will all vary depending on
0:38the biological agents you are handling
0:40surface decontamination is usually
0:44carried out using liquid disinfectant
0:46solutions every time you use
0:49disinfectants it's very important that
0:52you are confident that you are meeting
0:54the following four criteria you are
0:57using an appropriate disinfectant this
1:00must be effective against the biological
1:02agents you are handling and safe to use
1:05on the surfaces you are decontaminating
1:07the disinfectant is within its
1:10shelf-life
1:11also known as its expiry date
1:15it is being used at the correct
1:17concentration
1:19and it's in contact with the
1:22contaminated surface for the right
1:24amount of time to inactivate any
1:26biological agents present
1:29not all this in fact ins are effective
1:32against all biological agents so
1:35choosing the right disinfectant is
1:37important for example vegetative
1:40bacteria that is not in Spore form fungi
1:43including fungal spores enveloped
1:47viruses and non insisted protozoa can be
1:51neutralized by a wide range of
1:52disinfectant products mycobacteria
1:56non-enveloped viruses and insisted
1:59protozoa are more robust and therefore
2:02less susceptible to disinfectants
2:05bacterial spores are the most robust
2:08biological agents and are completely
2:10resistant to some disinfectant products
2:14you will need to gather information to
2:16help you decide which disinfectant to
2:19use this can come from product test data
2:22supplied by the manufacturer of the
2:25disinfectant peer-reviewed articles and
2:28in-house testing a combination of
2:31information from these sources would
2:34provide the most confidence in assessing
2:36the disinfectants effectiveness correct
2:40concentration is very important too low
2:43and it will not reduce the numbers of
2:46biological agents to a safe level too
2:49high and the disinfectant could damage
2:51the surfaces it contacts
2:56disinfectants are usually supplied in a
2:58concentrated form and need to be diluted
3:01before use you should read the
3:04manufacturer's instructions carefully as
3:07different concentrations may be needed
3:09for different biological agents for
3:12example a higher concentration may be
3:14specified for use with spore-forming
3:16bacteria the most common active
3:20ingredient in disinfectants is sodium
3:23hypochlorite which releases chlorine
3:26usually referred to as available
3:28chlorine commonly used diluted
3:31concentrations include 1000 parts per
3:35million which equates to 0.1% used for
3:39general surface disinfectant and 10,000
3:43parts per million which equates to 1%
3:45used for disinfection of blood spills
3:50manufacturers will not necessarily use
3:53parts-per-million
3:54when giving concentration they will
3:57often use weight volume or percentage
3:59for example the concentration might be
4:02described as five grams per 100 grams or
4:065 milliliters per hundred milliliters or
4:095 percent these are all the same
4:13if we start with a product concentration
4:16of 5% how do we work out how much we
4:19need to produce 1 liter of a solution
4:22diluted to 1,000 parts per million the
4:26first thing to do is convert the
4:28percentages to parts per million which
4:30we do by multiplying by 10 to the 4 so
4:345% becomes 50 thousand parts per million
4:39we then divide the end-use required
4:42concentration in parts per million by
4:44the concentrated source in parts per
4:47million so 1,000 divided by 50 thousand
4:51equals 0.02 we then need to multiply
4:55this by 1000 to give the figure in
4:59milliliters 0.02 times 1,000 equals 20
5:04so we need to add 20 milliliters of the
5:07concentrate to 980 milliliters of clean
5:11water to give us our 1 liter with a
5:14concentration of 1,000 parts per million
5:19remember most disinfectants will cause
5:23harm if they contact the skin and they
5:26may also give off harmful fumes personal
5:29protective equipment should be worn for
5:32example a lab coat gloves and eye
5:34protection disinfectants should be
5:38handled in a well-ventilated area or a
5:41biological safety cabinet especially
5:44when handling the concentrated form it's
5:48advisable to put the equipment on a tray
5:50to contain any splashes and spills when
5:55making up the diluted disinfectant you
5:58should start by measuring the correct
6:00amount of water and then measure the
6:02correct amount of concentrated
6:04disinfectant and carefully add the
6:07concentrated disinfectant to the water
6:09this will ensure that any splashes or
6:12spills are already diluted to some
6:15degree making them less hazardous not
6:18all disinfectants are supplied as a
6:21liquid some are supplied in tablet or
6:23powder form but the precaution of adding
6:26the disinfectant to the water still
6:28applies diluted disinfectants must be
6:32clearly labeled with the name and
6:34concentration and the use by time and
6:38date dilution will often shorten the
6:41shelf life compared to the concentrated
6:43form the label must also indicate any
6:47hazardous properties for example if it
6:50is an irritant or flammable the solid
6:53disinfectant must have dissolved
6:55completely and be thoroughly mixed with
6:58the water before it is used contact time
7:02sometimes refer to as dwell or exposure
7:05time is the time needed for a
7:07disinfectant to be in contact with the
7:09biological agents to reduce them to a
7:12safe level this is often overlooked but
7:16it is a very important factor contact
7:20times may differ depending on the
7:22contaminating biological agent for
7:25example mycobacteria may require more
7:28time due to their robust nature
7:31it is important to note that some
7:34disinfectant products may evaporate
7:36before the full contact time passes this
7:40is more likely in warmer environments
7:43where this occurs disinfectant must be
7:46reapplied to the surface and left for
7:49the remaining time to ensure the full
7:51contact time is achieved the shelf life
7:55or expiry date is the length of time
7:58that disinfectant product may be stored
8:01before the active ingredients begin to
8:03break down and the disinfectant will no
8:06longer be able to reduce biological
8:08agents to a safe level the shelf life
8:12will be noted on the disinfectant
8:14container usually in conjunction with an
8:17expiry symbol disinfectants must not be
8:20used after this date as they may have
8:23become completely ineffective for
8:26disinfectant products that require
8:28dilution the manufacturer's instructions
8:31will state for how long the disinfectant
8:34will be effective once diluted this
8:37should be used to calculate the use by
8:39date for the diluted product and this
8:42state should be recorded on the
8:44container if more disinfectant is needed
8:47after this time a fresh solution should
8:49be prepared it is important to note that
8:53the shelf life of disinfectants may be
8:56reduced if they are not stored
8:57appropriately manufacturer's
9:00instructions will describe how their
9:02products should be stored but in general
9:05products should be stored away from
9:07direct sunlight in a clean dry place
9:11disinfectants may become inactivated by
9:15contact with other chemicals or organic
9:18materials such as bodily fluids and
9:20residues solid organic matter can
9:24prevent the disinfectant from reaching
9:26the target biological agents within and
9:29beneath the organic material in these
9:32situations it may be necessary to clean
9:35the area with detergent to remove the
9:37bulk of the organic material before
9:39surface decontamination
9:41the disinfectant you may also need to
9:45increase the concentration of the
9:47disinfectant increase the contact time
9:50or use an alternative disinfectant
9:52product to maintain a safe working
9:57environment work surfaces should be
10:00wiped down frequently but it is also
10:03important to decontaminate surfaces
10:05immediately when there are knowingly or
10:08potentially contaminated keeping work
10:11surfaces clean will protect you and
10:14those who share your work area from
10:16exposure to pathogens it also helps
10:19prevent the spread of contamination
10:21outside the laboratory and improves the
10:24quality of your work by preventing
10:27cross-contamination between samples the
10:30type of work surface and its condition
10:33will affect how easy it is to
10:35decontaminate and keep clean smooth
10:39coated or sealed surfaces are easiest to
10:43decontaminate if these surfaces become
10:46damaged due to scratches or cracks or if
10:50they are made of a softer material like
10:52wood they can trap dirt debris and
10:55biological agents where wooden surfaces
10:59are used it might be advisable to cover
11:01them with plastic proprietary laboratory
11:04bench coating material can be used or
11:06heavy duty plastic sheet taped in place
11:09will do alternatively the plastic tray
11:13could be used which will also help to
11:16contain any spills if there is organic
11:20material or dried residue on the surface
11:23it should be cleaned with warm soapy
11:25water to avoid inactivation of the
11:28disinfectant from high loads of organic
11:30material disinfectant can be applied to
11:35a surface either from a spray bottle by
11:38pouring it carefully or by transferring
11:41it to a disposable tissue or a cloth for
11:43wiping the disinfectant must then be
11:49left for the required contact time if
11:51the disinfectant evaporates before the
11:54contact time
11:55the timer should be stopped and
11:57disinfectant reapplied before restarting
12:00the timer if the disinfectant is a type
12:05that leaves any chemical residues that
12:07could harm skin or damage the work
12:09surface these should be wiped away using
12:12clean sterile water finally the surface
12:16must be wiped dry before use hands
12:21should be washed after any
12:23decontamination procedure it is
12:28important to decontaminate reusable
12:30equipment such as glassware before it is
12:33washed and reused
12:36glassware may be fully immersed in
12:38disinfectant other equipment such as a
12:42pets will need to be wiped down exterior
12:48casings of equipment can be wiped down
12:51but decontaminating interior surfaces
12:53may require special procedures which
12:56we'll look at later
12:57if the disinfectant leaves any residue
13:01the equipment will need to be washed or
13:03wiped down with clean sterile water
13:08even if good microbiological practices
13:12and procedures are in place
13:14spills will occur a spill may appear to
13:18be very limited especially when it's a
13:20transparent liquid here
13:23switching to UV light activates a dye in
13:26the solution which shows us that it has
13:28splashed out over a much wider area
13:31cleaning up the spill might seem a quick
13:34and easy job but the UV light shows that
13:38a lot of contamination has been left on
13:40the bench and the gloves
13:42you must always wear appropriate gloves
13:45for dealing with a spill and these must
13:47be changed for fresh gloves before
13:49resuming work it's important that people
13:55know how to clean up a spill safely and
13:57effectively the initial mopping up must
14:01be done slowly and carefully working
14:03inwards from the edges of the spill to
14:06avoid dispersing the liquid over a wider
14:08area there will always be some
14:11contamination left on the surface which
14:14will need to be cleaned using an
14:15appropriate disinfectant working like
14:19this should ensure that you prevent and
14:22staff being exposed to the spilled
14:24biological agents transfer of the
14:27biological agents outside the laboratory
14:30and cross-contamination of samples the
14:35spill should always be mopped up and
14:37removed using absorbent materials such
14:40as disposable paper towels or gel
14:43preparations these materials can then be
14:47decontaminated by autoclaving
14:49incineration or disinfection before
14:52disposal the spill area should then be
14:56decontaminated with an appropriate
14:59disinfectant remembering the basic rules
15:01it should be within its shelf-life of
15:04the correct concentration and left on
15:07the surface for the correct contact time
15:09without drying out after this infection
15:14the surface must be dried before
15:16resuming work
15:18this is particularly important on floors
15:21to avoid slipping on a wet surface when
15:27clearing up large spills there's a
15:29greater risk of splashing so you may
15:32need additional splash protection such
15:35as disposable plastic shoe covers or
15:37rubber boots a plastic apron to protect
15:41the lab coat and gloves that will
15:44protect against the disinfectant where
15:48possible leave the area and allow any
15:51potential aerosols to settle out before
15:54returning to mop up for spill work
15:59slowly to reduce any splashing and wipe
16:02from the outer edges towards the center
16:05of the spill so that you don't increase
16:07the area of contamination
16:11once the spill has been mopped up change
16:14gloves and other PPE to avoid
16:17cross-contamination the spill area can
16:22then be decontaminated with disinfectant
16:25following the general guidelines where a
16:28large volume of proteinaceous material
16:30has been spilled such as blood or broth
16:33the disinfectant concentration and the
16:36contact time may need to be increased in
16:40addition the disinfectant should be
16:42applied to a wider area than the spill
16:45you may need to move furniture or
16:47equipment to make sure you have located
16:50all of the spilled material the surface
16:54must be dry before work is resumed some
16:59laboratories are equipped with spill
17:01kits these contain all the disinfectants
17:04and absorbent materials that are needed
17:06for dealing with a spill on rare
17:11occasions spills may occur within
17:13equipment for example a tube might break
17:17inside a centrifuge during a cycle if
17:21this happens you should follow
17:23manufacturer's instructions but the
17:25general procedure would be
17:28stop the machine immediately and leave
17:31it for at least 30 minutes to allow any
17:34aerosols inside the machine to settle
17:37put on appropriate PPE if there is a
17:41transparent lid on the centrifuge and
17:43you can see that the sealed buckets or
17:46rotor are not damaged then lab coat
17:48gloves and eye protection will be enough
17:51if the buckets or rotor do appear to be
17:54damaged or you can't see inside the lid
17:57then respiratory protection should also
17:59be worn in case there is a regeneration
18:02of aerosols from the spilled liquid when
18:05you open the lid carry out surface
18:09decontamination of the sealed bucket or
18:11rotor in situ before transferring it to
18:14the nearest biosafety cabinet the eye
18:20and respiratory protection can now be
18:23removed as the biosafety cabinet will
18:25contain any further aerosols or spills
18:29working in the biosafety cabinet remove
18:32the lid of the bucket or rotor pour
18:37disinfectant into the bucket or rotor
18:40spray any unsub merged parts and leave
18:44for the required contact time remove any
18:48unbroken tubes and discard them remove
18:54any large pieces of broken tube then
18:58pour the contents of the bucket or rotor
19:00through a sieve to capture any small
19:02pieces using forceps or tweezers place
19:08broken pieces directly into a sharp spin
19:13mop up any remaining disinfectant using
19:16absorbent tissue and place in a suitable
19:19container for autoclaving or immerse in
19:22disinfectant remove any chemical residue
19:26with ethanol or water and dry thoroughly
19:30check the bucket or rotor and the
19:33centrifuge for any signs of damage if it
19:36is damaged ensure it's not used and
19:39contact the supply
19:41to arrange repair or replacement a
19:43service visit may be advisable even
19:47where there is no obvious sign of damage
19:52in summary effective surface
19:55decontamination practices must include
19:58wearing appropriate PPE that protects
20:02against the biological agents and the
20:04disinfectant chemicals where necessary
20:08clean surfaces before disinfection use
20:14disinfectants that are suitable for the
20:16surface material effective against the
20:19biological agents freshly prepared and
20:22within their shelf life
20:25make sure disinfectants are used at the
20:28right concentration and with the right
20:31contact time disinfectants should be
20:36clearly labeled and stored properly
20:40remove any disinfectant residues with
20:43water or alcohol
20:51[Music]

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