Flexible endoscope:
monitoring of the final rinse-water
(Study note)

• Total viable count​ - weekly

• Environmental Mycobacteria - quarterly

• Pseudomonas aeruginosa - quarterly

Pseudomonas spp

• Bronchoscopes, cystoscopes and ERCP: Suspend the decontamination of bronchoscopes, cystoscopes and ERCP in the EWD or affected chamber until the full identification of the Pseudomonas is known and do not decontaminate bronchoscopes/cystoscopes/ERCP in affected EWD or chamber until the water quality has been improved (some models of EWD have two sides or chambers that can be operated independently).​​

• GI endoscope: Risk assess the continuation of GI scope decontamination.

Environmental / Non-tuberculous mycobacteria

• Bronchoscopes, cystoscopes and ERCP: Suspend the decontamination of bronchoscopes, cystoscopes and ERCP in the affected EWD or chamber until the problem has been resolved.​

• Review AAFB positive lavage results since previous negative mycobacterial test - look back exercise.

CFU >100cfu (repeated finding)

• Investigate the water source;

• Involve the EWD manufacturer to assess internal contamination and /or biofilm.

• Suspend the use of the EWD until the problem is resolved.

CFU < 1

• Satisfactory

• Continue using the endoscope as normal.

1 – 9 CFU

• Acceptable​

• Acceptable as a one-off result.​​ The endoscopy list can continue.​​ Monitor the result.​

10 – 100 CFU

• Unsatisfactory​

• Take the EWD out of service pending risk assessment and investigations,​​ (It must be remembered that by default the machine will have been operating potentially for a further 5​ days since the positive sample was taken).​​

• Test:​​
  Gram stain and oxidase test to presumptively identify Pseudomonas. Confirm identification of any oxidase positive Gram-negative organism.​​
  Send for identification if single organism presents or a significant proportion of organisms appears to be from a single species from colonial morphology.​​
  Do ZN stain for any GPB.​​
  Send these results to the Infection control team and Authorising Engineer/ Personnel (Decontamination).​​

• An incident team may consider other risk assessment procedures to assess the risk to patients, if the EWD is to be kept in service.​​

• Incident form (IR1)​.

• Run additional self-disinfection cycle on the EWD, or super- chlorination, undertake remedial work on the water distribution system to investigate the problem – e.g., check the purification/filtration system and any internal components on the EWD. Instigate a re-test of the rinse water.​​

1. If count is 10-50, and
   counts from the previous three weeks’ samples from the AER, have been below 10,
   then carry out an additional self-disinfection on the AER,
   re-test the rinse water and proceed to use the AER for all scopes.​​

2. If the count is between 10-50, and
   a count from the previous three weeks’ samples, from the AER, have been 10 or above
   then carry out an additional self- disinfection on the AER,
   re-test the rinse water and
   do not use the AER to process bronchoscopes, cystoscopes or duodenoscopes until re-samples show acceptable counts.​​

3. If the count is 51-100
   then carry out an additional self-disinfection on the AER,
   re-test the rinse water, and
   do not use the AER to process bronchoscopes or cystoscopies until re-tests show acceptable counts.​​

>100 CFU

• Unacceptable​

• EWD should be taken out of service until water quality has improved / issue resolved.

• Test and investigate as described in Unsatisfactory/10-100 CFU section.

• It is a requirement of BS EN ISO 15883-4:2009 that microbial contaminants of water used for final rinse applications should be maintained consistently below 10cfu/100 ml sampled when tests carried out in accordance with the BS EN ISO 15883 standard. Additionally, samples should be free of Legionella, Pseudomonas aeruginosa and Environmental mycobacteria.​

• Multidisciplinary teams should work together to identify the source of the contamination within the final rinse supply.

• Incident form (IR1).

Depending on the identification of organism, levels and persistence of problem consideration should be given to the need for a look back exercise and/or offering antimicrobial prophylaxis to patients who have had endoscopes used in invasive procedures decontaminated in the affected EWD/chamber in the time frame between last negative rinse water test and the positive finding.​