hen you’re a patient in a hospital, you’d like to think the doctors, nurses, or orderlies standing at your bedside had recently washed their hands, wouldn’t you?
You’d also probably be glad to hear that hospitals in recent years have pushed for more hand-washing stations — part of an effort to cut down on the spread of bacteria that thrive in hospitals, further compromising the health of people who are already sick.
There’s a problem here, however. Those sinks have been implicated in the spread of dangerous bacteria.
In a devilish case of unintended consequences, sinks have been linked to a number of outbreaks of serious infections in hospitals from Baltimore to Shanghai and many places in between in recent years. In one notable case, a hospital in the Netherlands took sinks out of the patient rooms in its intensive care unit in a bid to slow the spread of bacteria. (It worked.)
At a time when concern is mounting about antibiotic resistance, and when the specter of untreatable infections threatens the advances of modern medicine, finding ways to slow the development and spread of drug-resistant bacteria is a major preoccupation of infection control teams. As a result, evidence that hospital sinks could exacerbate the problem presents health care specialists with a quandary.
“The thing about the sinks is that they’re the cornerstone of infection control policy. … All of the [hospital] guidelines in the developed world talk about having sinks — the ratio of sinks per beds and where they are and that sort of thing,” said Dr. Michael Gardam, director of infection control at University Health Network, an institution comprising four Toronto hospitals.
When it comes to hospital sinks, there are two major issues.
First, the water coming into them can contain bacteria. That’s true of any sink, anywhere; municipal water treatment systems don’t produce sterile water. But a bug that isn’t a risk for a healthy person can be dangerous for someone whose immune system is suppressed to prevent rejection of a donor organ or who is recuperating from a serious operation.
The other problem is that sinks, particularly the pipes that drain them, are ideal places for bacteria to proliferate. The bugs form what are known as biofilms – colonies where they gang together and attach to a surface. These water-dwelling bacteria especially like p-traps, the U-shaped bend in pipes that drain the contents of a sink.
Getting rid of biofilms once they form is, well, pretty much impossible. There are cleaning tricks hospitals try, but even those generally only lower the bacterial count for a while.
“Once you have the biofilms in there, short of ripping the sinks and the piping out, it’s impossible to get rid of. And in fact, even if you do that, it frequently comes back,” said Dr. Alex Kallen, a medical officer in the Center for Disease Control and Prevention’s division of health care quality promotion.
He said it’s not entirely clear how much of a risk biofilms in hospital sinks pose. These bacterial colonies are generally — though not always — found in the pipes leading away from sinks, so people using the sinks shouldn’t, in theory, have contact with them.
In fact, to see if bacteria from biofilms in sinks drains could find their way back up to contaminate hands, the CDC ran an experiment where it had people wash their hands in sinks with contaminated drains. It saw no evidence of bacteria transferring from sinks to hands.
But Kallen said more experiments are underway because of the number of reports that put sinks squarely at the heart of hospital outbreaks.
Gardam has firsthand experience with an outbreak caused by a sink. It was a bad one. Three dozen patients in intensive care contracted a drug-resistance bacteria; an investigation after the fact said five died because of the infection.
“Once you have the biofilms in there, short of ripping the sinks and the piping out, it’s impossible to get rid of.”
Dr. Alex Kallen, CDC
Figuring out how the patients were getting infected took sleuthing, but eventually suspicion fell on some sinks in the ICU. They had gooseneck faucets that directed water straight down into the drain. The pressure created back splash, with tiny droplets of bacteria-laced water spraying onto nearby porous surfaces where medical staff prepared tubing and other equipment used in patient care.
Gardam ordered staff to stop using the sinks, going so far as encasing them in garbage bags. There were no new cases after that.
The hospital subsequently made a number of changes, which have been adopted elsewhere as well, Gardam said.
“Some of the stuff we’ve learned … is: Don’t have the gooseneck (faucet) drain directly into the drain; have it drain off the side of the bowl. Don’t allow it to splash. Make sure it’s deep enough that it can’t splash on you and splash on your clothing. Make sure that the stuff around [the sinks] is waterproof.”
Exacerbating the problem is the fact that biofilms that develop in hospital sinks may house really bad bugs – bacteria that are resistant to key antibiotics. That’s because sinks aren’t just used to wash hands. Staff sometimes use them to dispose of patient specimens – urine, for instance – or to drain the dregs of an intravenous bag of antibiotics.
“It’s just like: How do you use your kitchen sink? You dump your disgusting stuff down there and then you wash your hands,” said Dr. Trish Perl, an infection control expert who is chief of infectious diseases at the University of Texas Southwestern Medical Center in Dallas.
Hospitals should have clean sinks — for hands — and dirty sinks, for disposing of patient specimens, said Kallen. But some health care workers would argue it’s safer to tip a specimen into the nearest sink rather than walk down a hallway with something that might spill.
“There does seem to be at least anecdotal evidence that if you discard patient specimens down sinks, then you can contaminate the drains with the things that are in those specimens — which, if they’re in the hospital, are more likely to be multidrug resistant [organisms],” said Kallen.
“Now whether or not that’s a true source of transmission to other patients is controversial. But you certainly can contaminate the sink that way.”
As problems with sinks have become apparent, experts have been working to design better and safer sinks.
But even there it’s important to look for unintended consequences. For instance, a couple of studies, including one done by Perl, looked at bacterial accumulation in electronic eye faucets — the no-tap sinks where water flow is activated by placing hands in front of a sensor.
The suspicion is that sinks without taps would actually reduce the risk that freshly washed hands would be recontaminated by turning off taps. But some appear to be more likely to accumulate bacteria, Perl said, explaining they have multiple internal valves and more surfaces on which biofilms can form.
It’s an important lesson, she said: New sink designs need to be tested, in the way drugs are, to ensure they are actually better.
“We need to start insisting on studies so that we understand the implications of introducing novel technologies before we do it,” she said.
Health care specialists say concerns about hospital sinks have provided them with another lesson: Use alcohol gel. Some people still believe it dries out their skin, and it’s not effective on its own if a health care worker’s hands are soiled.
But there’s no doubt that it can help curb the spread of bacteria. And it is, in fact, what the CDC recommends when hands need to be cleaned but aren’t soiled with a contaminant that gel won’t remove.
“But you know, the cornerstone of hand washing isn’t sinks, it’s alcohol gel,” said Gardam. “And the reason why the world has moved to alcohol gel is that it’s a lot cheaper, it works better, it’s faster, you can wash your hands while you’re walking, it doesn’t dry your hands out as much. I can go on and on and on.”