A Contaminated Sink Trap Drove an ICU Acinetobacter Outbreak. Decontaminating the Drainage System Ended It.
Key Takeaway
A multidrug-resistant Acinetobacter baumannii outbreak in an intensive care unit was traced to a contaminated sink trap, which had seeded the entire shared horizontal drainage system. Standard measures did not stop it. A weekly protocol that cleaned the full drainpipe chase with bleach decontaminated the reservoir and significantly reduced infections.
The Study
Over a 38-month period, investigators managed a multidrug-resistant Acinetobacter baumannii outbreak in a surgical and medical intensive care unit. Between June 2004 and March 2005, 16 patients were infected and 2 were colonized, and 11 of the 16 infected patients (69%) carried a single clonal strain. A systematic search for the environmental source identified a contaminated sink trap that likely represented contamination of the entire horizontal drainage system serving the unit. Beginning in March 2005, the team introduced a weekly full drainpipe-chase cleaning protocol using sodium hypochlorite (bleach) for all 24 ICU and waiting-area sinks on the shared plumbing.
Key Findings
The reservoir was a sink trap
The environmental source was traced to a sink trap in an ICU patient room, likely reflecting contamination of the entire horizontal drainage system shared by the unit.
A single clone caused most infections
Of the 16 infected patients, 11 (69%) carried one clonal multidrug-resistant Acinetobacter baumannii strain, linking the cases to a common environmental source.
Drain decontamination cut infections
A weekly bleach cleaning of the full drainpipe chase, applied to all 24 shared sinks, decontaminated the reservoir and significantly reduced the incidence of MDR A. baumannii infection (P < .01).
Standard measures alone were not enough
The outbreak was brought under control only once the drainage-system reservoir itself was addressed, not by routine infection-control measures alone.
What This Means For Your Facility
This 38-month report is strong evidence that a single contaminated sink trap can seed an entire drainage system and sustain an ICU outbreak, and that infections fall only when the drain reservoir itself is addressed. The same shared-drainage dynamic exists in the floor drains of commercial, food-service, and healthcare buildings.
La Forgia's team controlled their outbreak with a labor-intensive weekly bleach protocol across every sink on the plumbing run. A waterless trap seal takes a preventive approach to the same reservoir by removing the standing water a conventional trap relies on and acting as a one-way valve that allows water to drain but restricts the retrograde movement of air and aerosols from the drainage system into the room. This study did not test a trap seal, and no study has tested a trap seal against an infection endpoint, but its lesson, that the drain reservoir has to be addressed, is why a waterless trap seal belongs in a preventive maintenance program as a supportive engineering control that complements, not replaces, infection prevention.
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Address the Drain Reservoir Before an Outbreak
Green Drain removes the standing water where drain biofilm establishes, restricting the upward movement of air and aerosols from the drain. Built for a preventive maintenance program.