CSC Study Day
He highlighted that these documents sometimes contain information that is conflicting or lacks clarity – for example, there is no agreement over the level of residual protein. He highlighted guidance within the HTM 01-01 on residual protein numbers, which states that the upper limit of 5 µg per side of instrument should be achieved, with a need for continual improvement. He pointed out that the reasons for the need for ‘continued improvement’ is the fact that “there is actually no safe level” of protein. The guidance within NICE IPG666 states that intracranial transfer of 0.01 µg of brain tissue could result in the recipient having a 50% chance of becoming infected with CJD. “This is a miniscule amount required
for transmission, but the 5 µg [in the aforementioned HTM 01-01] gives us many hundreds of doses,” he commented. Standard BS EN 15883 states it should be less than 6.4 µg per cm2
. He pointed out that, given the incubation
period of 1-42 years, it is difficult to learn from incidents which might otherwise prompt efforts to change practices. Departments often say they are “following manufacturers’ instructions” but it is the processor that is accountable and responsible for ensuring the desired result. Therefore, they must carry out tests to prove the required levels of decontamination have been achieved. There are conflicting messages around testing methods, however. Guidance HTM 01-01 refers to measuring ‘directly on the surface rather than by swabbing or elution’, while the standard BS EN ISO 15883-1 2009 refers to the ‘Biuret method (swabbing) or ortho-phthalic-acid-dialdehyde OPD (elution) or Ninhydrin. He stated that testing is a case of “horses for courses”, depending on the design challenges of the instrument and he went on to show some slides of some difficult to clean instruments. In some cases, neither ‘measuring directly on the surface’ or ‘swabbing’ would give an accurate indication of protein located in the hard to
access areas; elution in a lab might be the best option in such cases and the lab may need to disassemble the instrument. He highlighted some test results on ‘remote working surgical instruments’, which led to some improvements. By keeping the instruments moist and speeding up the process (by removing transport delays), the protein residues were reduced to a quarter of the levels detected prior to the changes. “If we don’t test and we don’t know, we are just blindly carrying on,” he asserted. While keeping instruments moist will
improve protein removal, who is responsible for monitoring this? Sterile services departments often see variations in practices – some instruments will arrive at the SSD properly bagged and sprayed, to keep them kept moist, while others arrive simply wrapped in paper and are allowed to dry out. Automation is also important – ideally, we should aim to move away from manual processes, such as brushing, to the flushing of lumens. “The problem with manual processes, is that we all have off days,” he commented. He also suggested that sterile services departments should double process devices where inspection is not possible – this may include manual, ultrasonic or connection to lumens in the washer-disinfector. It is important to quantify the residual protein, using the best methods available and departments should “review, revise and improve”. If resolution is not possible, this should be included on the Risk Register.
Infection risks and laundry The afternoon session looked at the risks associated with laundry decontamination. Karren Staniforth, from the UK Health Security Agency, shared her findings and observations from investigations into outbreaks across the UK. She highlighted the risk of contamination
to people handling the laundry and the risks of patients acquiring infection from re-contaminated laundry, citing a range of
literature as evidence that these acquisitions occur.
Among the literature was an investigation into
an outbreak of mucormycosis in a paediatric oncology unit – linked to water damage arising in a linen store, located adjacent to the parent’s shower room (Garnet et al, 2008). This demonstrates how poorly maintained laundry storage rooms can pose a potential risk. However, recontamination of laundry can also occur due to contact with laundry staff with skin or enteric infections and poor practice. Other routes for contamination include laundry floors, roll cages and vans, when there is a failure to follow cleaning and handling procedures, which prevent recontamination. There is also a risk arising from decontamination failures. Linen may appear clean, but the microbial load may remain high if thermal disinfection has not been reached. Temperature and contact times need to be achieved consistently and laundry decontamination should be a quality assured process. Changing the load (without re- validation) or pausing and restarting the continuous batch washer (CBW) after it has cooled can cause failure, but these may go undetected and unreported. She pointed out that spore forming bacteria
such as Bacillus cereus and Clostridioides difficile will survive disinfection (e.g. 71o
C
for three minutes). Spores are removed by mechanical action and dilution, but if contamination is high, a significant number of potentially infectious spores can remain attached to linen. This is particularly a problem when bacterial contaminates replicate during transportation of used linen, during the warmer summer months. She concluded that:
l Bacillus cereus is implicated in 57% of all laundry-related outbreaks of infection.
l Cases and outbreaks may be undetected and unreported.
l It is easier to maintain control than to reduce counts once control has been lost.
l Active laundry testing is recommended during summer months.
l Total blood culture isolates can easily be monitored throughout the year.
l Simply increasing the rinse-water volume may not be sufficient to regain control and excess water may have a negative impact on mechanical action.
l More research, guidance, support, and training would be useful in preventing and managing these outbreaks and incidents.
It was evident, from Karren Staniforth’s presentation, that laundry validation is not as
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