RAPID MICROBIOLOGY
approved in more than 50 countries. “IDEXX brought over all the equipment that is necessary to carry out the sampling and testing,” explained Phil Mitchell. “The big selling point for me was the speed of the test – just 24 hours, with no additional confirmation steps. The simplicity was a key factor too, and it became evident that another benefit was that we could take a sample and process it straight away, overcoming previous issues we had had with the storage and transportation of the samples. Within 24 hours we’d know exactly what we were dealing with, including having a quantifiable result.”
“Also, if a patient contracted Pseudomonas, we would be able to treat the situation sooner rather than later, and immediately check all appropriate outlets and have the results within 24 hours.” Impressed with the presentation from IDEXX, Phil Mitchell and Dan Samworth developed an action plan to test the system, and decided on a two-month trial. IDEXX ran a training course for them and a number of colleagues on how the system works and how to use it. Dan Samworth, who was tasked with implementing the trial, and taking the majority of the samples, said: “In the trial, we took two samples per outlet. One was sent to a UKAS-accredited laboratory, and we processed the other one on the Pseudalert equipment. We took 50 samples in total.”
Confident in the results
Phil Mitchell said: “Using the Pseudalert system on our samples, we were picking up Pseudomonas that the lab did not. Because the system is in our control, we are really confident with the results.” Phil Mitchell and Dan Samworth presented the results of the trial to Claire Hennessy, the Trust’s head of Operational Estates and Facilities Management, explaining how impressed they were, and that they wished to proceed with purchasing the system from IDEXX. Phil Mitchell said: “We were able to utilise the Water Hygiene budget which was allocated to us. IDEXX delivered training to me, Dan, and the five members of the Water Hygiene team. The IDEXX trainers were all very knowledgeable. They made it a simple, step-by-step process. Everyone in the team picked it up very easily. That’s the beauty of it – it’s so simple. We now cascade the training to any new members of staff as they come on board.”
Bacterial enzyme detection The test is based on a bacterial enzyme detection technology that signals the presence of P. aeruginosa through the hydrolysis of a substrate in the Pseudalert reagent. P. aeruginosa cells rapidly grow and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the reagent. Actively growing
104 Health Estate Journal October 2018
Phil Mitchell, left, Water Hygiene and Environmental Estates officer, and Dan Samworth, Environmental Estates supervisor, at Oxford University Hospitals NHS Foundation Trust.
strains of P. aeruginosa have an enzyme that cleaves the substrate in the reagent to produce blue fluorescence under ultraviolet light. The Pseudalert test detects P. aeruginosa at 1 colony-forming unit per 100 ml water sample within 24 hours.
Phil Mitchell explained: “Taking a water sample is no different to taking one for a laboratory, except that the Pseudalert bottles have a specific fill point. The team members have a designated number of outlets to sample, and they return with those to the water hygiene workshop for processing. The sample is processed the same day, within a matter of hours of being taken.”
To test for the presence or absence
of P. aeruginosa, the IDEXX reagent is added to the sample, and the vessel is then capped and shaken to dissolve the reagent, followed by incubation at 38˚C for 24 hours. After incubation, the sample is read under ultraviolet light. Blue fluorescence indicates the presence of P. aeruginosa.
Quantification process
For quantification the reagent is added to the sample, followed by IDEXX antifoam solution. The sample is poured into an IDEXX Quanti-Tray (for counts from 1-200) or Quanti-Tray/2000 (for counts from 1-2,419). The tray is sealed using a Quanti-Tray sealer, and incubated at 38˚C for 24 hours. When read under ultraviolet light, blue fluorescence indicates the presence of P. aeruginosa. The user counts the positive (blue fluorescent) wells, and refers to the most probable number (MPN) for enumeration.
A compact system
The Pseudalert system takes up only a small space in the water hygiene workshop. It comprises sterile sample bottles; Pseudalert reagent; Quanti-Trays, the Quanti-Tray sealer; an incubator, which holds up to 12 Quanti-Trays, and a UV box for reading the samples. An anti- foam solution is used in hard water areas. “The water in this area is hard, which makes the anti-foam solution a must- have,” explained Dan Samworth. “All the guys have really taken to Pseudalert. I like doing the test. It’s great. It’s five minutes of feeling like you’re in a lab.” Phil Mitchell added: “We’ve now utilised Pseudalert for almost a year across the Trust’s three sites: the John Radcliffe Hospital, Churchill Hospital, and two theatres at Nuffield Orthopaedic Centre, the remainder of which is the responsibility of the Trust’s PFI partner. Lisa Butcher, our lead nurse and manager for Infection Prevention and Control, is very impressed with the system, and happy that we have it.”
Lisa Butcher said: “With IDEXX we can take immediate remedial action, find out why the issue occurred, and act on the information to prevent further events. This level of immediacy and accuracy has made a significant contribution to our proactive and reactive infection control. Our Operational Estates and Infection Prevention and Control teams work closely together, with excellent communications and mutual understanding, so we manage our water safety collaboratively. This excellent working relationship has also contributed to the improvements we have seen over the past year.”
Lead nurse and manager for Infection Prevention and Control at Oxford University Hospitals NHS Foundation Trust, Lisa Butcher.
Contractor costs reduced The Trust’s Water Hygiene team was established four years ago. Claire Hennessy, head of Operational Estates and Facilities Management, explained: “Being able to control and manage our own water system has been a huge benefit. It means we have control over the work done. It has reduced our contractor costs phenomenally.”
Describing the working relationship, Phil Mitchell said: “IDEXX is a great company
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