# Stopping an outbreak of Pseudomonas aeruginosa ST111 by temporarily blocking the siphon to disinfect it before the transition to the wastewater drain

## TL;DR

A method to stop a Pseudomonas aeruginosa outbreak by temporarily blocking and disinfecting siphons in hospital washbasins was developed.

## Contribution

A practical, low-cost solution to disinfect siphons without disassembly during outbreaks of multi-resistant pathogens.

## Key findings

- Temporarily blocking siphons allowed effective disinfection and stopped the outbreak.
- Self-disinfecting siphons may reduce colonization and infections in high-risk areas.
- Outbreaks of multi-resistant pathogens require siphon sampling and disinfection.

## Abstract

Resulting from an analysis of an outbreak of carbapenem-resistant Pseudomonas (P.) aeruginosa, the siphons of washbasins in patient rooms were identified as source of colonizations and/or infections. To avoid installing new siphons, a solution was needed to temporarily block the siphon before the transition to the wastewater drain.

By temporarily blocking the drain before the transition to the wastewater drain with a balloon, it was possible to disinfect the traps without disassembly and stop the outbreak.

Temporarily blocking the drain can stop outbreaks originating from the siphon. However, this does not protect the siphon from renewed contamination by patients, or subsequent biofilm formation. Therefore, the only option in cases of known patient colonization or infection with critical multi-resistant pathogens that can colonize the siphon is to disinfect the siphon after the patient’s discharge by temporarily blocking it. Since even non-resistant wastewater bacteria can cause infections, especially in immunocompromised patients, an option for obviating this problem would be to dispense with washbasins in high-risk areas such as units for intensive care, burns, cystic fibrosis and neonatology. As a general rule, water used to wash patients in bed must be disposed of in separate drains outside the patient's room. Since self-disinfecting siphons significantly reduce emissions from the siphon, combined with lower colonization or infection of exposed patients; their installation in high-risk areas may be useful for reducing nosocomial infections. However, in the event of an outbreak of a multi-resistant pathogen with the ability to colonize the siphon, it is necessary take samples of siphons and, if detected, to disinfect them by temporarily blocking them.

The option of disinfection of siphons by temporarily blocking them is a technically simple, economically immediate measure.