A study of hospital infection outbreaks in a transplant ward in Canada reveals that shallow basins placed high and gooseneck spouts were responsible for those episodes.
In such a design, aimed at making water flowing directly into the drain below, ironically, pressure from the spout splashed water out of the drain, spraying nearby surfaces.
Now the bug behind the infection outbreak was identified as Pseudomonas aeruginosa. The germ thrives in drains and forms bio-films or, more simply, slime and sludge.
So ultimately as a result of splashing, the Pseudomona could have landed on the counter top and maybe even on the bed too.
Pseudomonas bacteria are everywhere. In fact, the bug would probably be found in most household drains if anyone bothered to check. But no one would. The bacteria pose no threat to healthy people.
But it's a different story for patients who have just received an organ transplant. These patients are on drugs that suppress their immune systems so their body doesn't reject the donor organ, and their systems are already weakened by whatever caused the need for the transplant.
In these and other seriously ill hospitalized patients, Pseudomonas can trigger skin, wound or bloodstream infections or pneumonia. And if the bacteria become resistant to antibiotics - as bacteria in hospitals are wont to do - the infections they cause can be challenging to treat.
The Canadian outbreaks had occurred between December 2004 and March 2006 at Toronto General Hospital.
In all, 36 patients were either infected or colonized with the outbreak strain. (Colonized means a person is carrying the bacteria on the skin or in cavities like the nostrils, but the bacteria isn't causing illness.)
Two-thirds of the patients were infected and 17 died. A retrospective review of the deaths concluded the outbreak strain killed five patients and contributed to the deaths of seven others, according to the study published in the January issue of the journal Infection Control and Hospital Epidemiology.
Initially the cases related to patients who were located near one another, leading the infection control team to suspect health-care workers were transferring the bugs on their hands. But when other patients started cropping up, it became apparent the answer wasn't that simple.
When transplant patients in the hospital's medical and surgical intensive care unit, transplant step-down unit and transplant ward were becoming infected with a multi-drug resistant strain of Pseudomonas, the infection control team began an intensive investigation to determine how patients and bugs were coming into contact.
Given Pseudomonas aeruginosa's fondness for moisture, the infection control team began testing sinks. Bacteria were found in some but not others, and in some it was only found intermittently.
Painstaking investigations led to the conclusion that the design of the sinks was responsible.
Each single-patient room in the medical and surgical intensive care unit had its own hand hygiene station. They were located just over a metre from the head of the patient's bed and adjacent to a counter top health-care workers used to prepare medication and sterile dressings for the patient.
Hospital room surfaces were covered with black paper, a fluorescent gel was injected deep into the drain and someone washed his or her hands.
Using an ultraviolet light in the blacked out room, the investigators saw fluorescent splatter had travelled at least one metre - as far as the head of the bed and onto the preparatory counter. The authors believe smaller droplets probably carried further.
"The main reason that we published this is because we thought that this was an important lesson. People need to know this," says Dr. Michael Gardam, senior author of the study.
"The message from this for us was that hand hygiene sinks are obviously really important - and they have to be the right design. And they have to be in the right place. And they can't be splashing."
On the strength of that evidence, the hospital took the step of removing the sinks. No new cases were reported after that. New sinks with a different design were installed, with splash guards between the sink and the treatment preparation area. Testing showed the splatter problem had been solved.
Dr. Andrew Simor, an infection control expert at Toronto's Sunnybrook Health Sciences Centre, says the outbreak report identifies two issues of which hospitals should take note.
While single rooms with sinks are ideal for cutting the risk patients will pick up hospital-acquired infections, those sinks shouldn't be located too close to beds or treatment preparation areas.
And the design of sinks is critical. Simor says hospitals can't prevent biofilms from forming in drains, despite their best efforts. But by limiting the potential for splashing, they can perhaps keep those biofilms where they can't hurt patients, Helen Branswell reports for Canadian Press.
"We're always learning," says Simor, who heads the microbiology department of his hospital.
"And that's why this was an instructive report. Because it does remind us that it's not just as clear cut as having a private room with a sink."