An ESBL Klebsiella Outbreak Was Linked to Contaminated Handwashing Sinks.
Key takeaway.
An outbreak of ESBL-producing Klebsiella oxytoca in an ICU was linked to contaminated handwashing sinks, where the sink isolates matched the patient isolates by molecular typing. The outbreak affected 66 patients over several years and was brought under control only with intensified sink cleaning, sink-drain modifications, and an antimicrobial stewardship program.
The study.
This investigation tracked an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella oxytoca in a medical-surgical ICU in Toronto, Canada, from 2006 to 2011. Environmental sampling of the ICU handwashing sinks recovered K. oxytoca whose PFGE patterns were identical to the patient case isolates, linking the sinks to the infections.
Sixty-six patients acquired ESBL-producing K. oxytoca over the outbreak. Transmission appeared to occur both from the contaminated sinks and between colonized or infected patients, and the outbreak persisted despite hand-hygiene auditing, screening, and contact precautions.
The infections stopped only after a bundle of measures aimed at the sink reservoir: cleaning the sinks three times a day, modifying the sink drains, and introducing an antimicrobial stewardship program. A separate small ward cluster was controlled by screening and contact precautions alone, reinforcing that it was the sink reservoir that drove the ICU outbreak.
Key findings.
- Handwashing sinks matched the patient isolates Environmental cultures from ICU handwashing sinks yielded Klebsiella oxytoca with PFGE patterns identical to the clinical case isolates, linking the sinks to the patient infections.
- 66 patients over about 4.5 years The ICU outbreak affected 66 patients between 2006 and 2011, a protracted course driven by a persistent sink reservoir.
- Standard measures alone did not stop it The outbreak continued despite hand-hygiene auditing, patient screening, and contact precautions, because those measures did not address the sink reservoir.
- Addressing the sinks ended it Infections stopped only after sink cleaning three times a day, sink-drain modifications, and an antimicrobial stewardship program were introduced.
What this means for your facility.
This outbreak is a clear example of the handwashing sink itself being the reservoir, and of how long an outbreak can run when standard measures do not reach the drain. It was resolved only when the sinks and their drains were directly addressed. The same standing-water sink and floor-drain traps exist throughout commercial, food-service, and healthcare buildings.
Green Drain removes the standing water a conventional trap relies on with a one-way silicone valve that allows water to drain but restricts the retrograde movement of air and aerosols from the drainage system. This study did not test a trap seal; in the independent SGS aerosol-retention test (Report QDF25-0049810-01) the GD3 retained over 99.9% of an aerosolized MS2 bacteriophage viral surrogate in a controlled bench test. That surrogate retention is a physical bench measurement, not a test against a real pathogen or infection endpoint.
Because the sink reservoir had to be addressed directly to end the outbreak, this study supports building drain protection into a preventive maintenance program alongside cleaning, hand hygiene, and stewardship, rather than relying on those measures alone.
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