The testing protocols for washer disinfectors are very similar to those required for ultrasonic baths as highlighted in last month’s article. They fall into three main categories; weekly, quarterly and annual tests.
A weekly protein residue test should be carried out on one of the instruments that has been through the washer disinfector cycle. However, unlike with ultrasonic baths, instruments don’t normally need to be rinsed with RO (reverse osmosis) or distilled water, because the washer disinfector will incorporate this as part of the rinse cycle as standard. HTM01-05 recommends the use of a rinse aid in order to help reduce water spotting on stainless steel instruments, which can cause rusting and inhibits the lubrication of joints - this is a particular concern in the case of forceps.
If an instrument fails the protein residue test, firstly, double-check that the washer disinfector is not displaying any visible error codes and that it contains detergent. Then run another cycle. If the test is failed again an engineer should be consulted, as this could be indicative of a problem with the washer disinfector itself.
Weekly safety checks are also required for washer disinfectors to confirm there is no visible damage that could invalidate its processes. This includes checking that rotor arms function without stiffness, the door opens and closes smoothly and the rubber, or silicone, gasket around the door is not damaged. Although there is no test as such for these checks, they should be recorded and filed as part of the practice’s decontamination processes.
On a quarterly basis, washer disinfectors must complete a cleaning efficacy test (soil test), using a PCD (process challenge device) and CEI (chemical efficacy indicator). It’s important to note that this is a manufacturer-led test; therefore their guidelines should be adhered to. However, in the absence of any manufacturer guidance, HTM01-05 advice should be followed. Finally, all washer disinfectors require annual validation by an accredited engineer. The use of washer disinfectors is considered best practice, helping eliminate the need for manual cleaning and reducing the risk of sharps injuries. Ultimately, HTM01-05 will require all practices to meet best practice standards, but currently there is no timetable for this to come into effect.
Manual cleaning
Following a wash cycle, instruments must be visually inspected and if debris is present, the instrument cannot be sterilised. HTM01-05 states that materials such as cement should be cleaned straightaway, as research suggests that doing so makes the cleaning process easier. There are a number of specialist pre-wash foams and sprays available that help to break down these materials and start the decontamination process before cleaning takes place.
Approximately 70 per cent of dental practices still conduct some sort of manual cleaning and although it is still acceptable and sometimes necessary, manual cleaning is very difficult to validate due to inconsistencies in individuals cleaning methods. Therefore, it’s important to have protocols in place, such as a set emersion technique, which the team must follow and document.
Tests for autoclaves
Vacuum and non-vacuum autoclaves require several tests, the first is an ACT (automatic control test) that tests the parameters of the autoclave and needs to be completed every morning.
This test necessitates the use of a class 6 indicator (also known as a TST), which measures time, steam and temperature within the autoclave. This indicator will only change colour when three specific criteria have been met;
- the time has been achieved (a minimum of 3.5 minutes, or whatever time the manufacturer advises),
- λ the steam has penetrated into the strip and
- the temperature has been achieved (134?c – 137?c).
If any of these parameters are not met, the indicator will not change colour. In the case of vacuum autoclaves, they also require a steam penetration test once a day, using either a Helix device or Bowie and Dick.
A printable data logger automatically records and prints out this test, providing written confirmation of sterilisation times, temperature, and whether the test was passed successfully, creating a unique batch number. If you have a printer rather than a data logger the test printouts should be kept in airtight bags to prevent the ink fading, thereby providing documentary evidence of the effectiveness of the autoclave.
Older autoclaves, those with an analogue motherboard, can be connected to a printer. Consult your manufacturer for advice. Autoclaves without a data logger or printer can be tested using a stopwatch to monitor the min/max temperature time and sterilisation time, this is the ACT. These times should be noted in a logbook. When temperature readings are compared to previous days they should be the same.
At the end of each day, the inner chamber – where clean and dirty water resides – should be physically drained and left to dry. This helps prevent the formation of bacteria. To keep the autoclave in good running order, door seals and gaskets should be dried after each cycle with a lint-free cloth.
Residual air tests and an air leakage test must be carried out weekly, however, some autoclaves cannot perform these tests. In this case, consult the manufacturer for advice.
HTM01-05 discusses thermometric testing. However, this should be completed on an annual basis, by a competent person, or an engineer, as part of the validation process.
Pouching instruments
Those practices using a vacuum autoclave should pouch instruments before sterilisation, as this determines the current limits of either 21 or 60-day storage (in Wales, the limit is 30 or 60 days storage).
After pouching, it is important not to overload the autoclave. A gap is required between each pouch, sufficient to allow the air to circulate and effectively dry the instruments. Pouches packed too tightly create bacteria ‘traps’.
Ideally, instruments should be kept pouched until needed. It is currently only best practice to store sterilised instruments in a dedicated room, so if they are stored in the surgery, instruments must be kept in a closed airtight cupboard, out of the 1.5 metre aerosol area.
Amendments to HTM01-05
The Department of Health has always said that HTM01-05 is a living and constantly evolving document, and naturally, since its publication in 2009, technology has improved and research has uncovered more relevant data on cross-infection control and decontamination.
The Department has recently issued a statement about the timing of publication of the amended HTM01-05, which will be based on recent evidence. But, before this revised document is issued, the Department is reviewing research into washer disinfectors, the storage of sterilised dental instruments and protein residue tests, all of which have been the cause of some debate amongst decontamination experts and dentists alike.
However, with or without an amended document, the purpose of HTM01-05 remains unchanged; eliminating or at least reducing the risk of cross-infection in primary dental care practices, an objective that is the responsibility of every member of the practice team.