Friday 18 May 2007
One of the easiest ways to prevent the spread of hospital infections is also one of the most neglected.
One ordinary December day, I took a tour of my hospital with Deborah Yokoe, an infectious disease specialist, and Susan Marino, a microbiologist. They work in our hospital's infection-control unit. Their full-time job, and that of three others in the unit, is to stop the spread of infection in the hospital. This is not flashy work, and they are not flashy people. Yokoe is forty-five years old, gentle voiced, and dimpled. She wears sneakers at work. Marino is in her fifties and reserved by nature. But they have coped with influenza epidemics, Legionnaires' disease, fatal bacterial meningitis, and, just a few months before, a case that, according to the patient's brain-biopsy results, might have been Creutzfeld-Jakob disease - a nightmare, not only because it is incurable and fatal but also because the infectious agent that causes it, known as a prion, cannot be killed by usual heat-sterilization procedures.
By the time the results came back, the neurosurgeon's brain-biopsy instruments might have transferred the disease to other patients, but infection-control team members tracked the instruments down in time and had them chemically sterilized. Yokoe and Marino have seen measles, the plague, and rabbit fever (which is caused by a bacterium that is extraordinarily contagious in hospital laboratories and feared as a bioterrorist weapon). They once instigated a nationwide recall of frozen strawberries, having traced a hepatitis A outbreak to a batch served at an ice cream social. Recently at large in the hospital, they told me, have been a rotavirus, a Norwalk virus, several strains of Pseudomonas bacteria, a superresistant Klebsiella, and the ubiquitous scourges of modern hospitals - resistant Staphylococcus aureus and Enterococcus faecalis, which are a frequent cause of pneumonias, wound infections, and bloodstream infections.
Each year, according to the U.S. Centers for Disease Control, two million Americans acquire an infection while they are in the hospital. Ninety thousand die of that infection. The hardest part of the infection-control team's job, Yokoe says, is not coping with the variety of contagions they encounter or the panic that sometimes occurs among patients and staff. Instead, their greatest difficulty is getting clinicians like me to do the one thing that consistently halts the spread of infections: wash our hands.
There isn't much they haven't tried. Walking about the surgical floors where I admit my patients, Yokoe and Marino showed me the admonishing signs they have posted, the sinks they have repositioned, the new ones they have installed. They have made some sinks automated. They have bought special five-thousand-dollar "precaution carts" that store everything for washing up, gloving, and gowning in one ergonomic, portable, and aesthetically pleasing package. They have given away free movie tickets to the hospital units with the best compliance. They have issued hygiene report cards. Yet still, we have not mended our ways. Our hospital's statistics show what studies everywhere else have shown - that we doctors and nurses wash our hands one-third to one-half as often as we are supposed to. Having shaken hands with a sniffling patient, pulled a sticky dressing off someone's wound, pressed a stethoscope against a sweating chest, most of us do little more than wipe our hands on our white coats and move on - to see the next patient, to scribble a note in the chart, to grab some lunch.
This is, embarrassingly, nothing new: In 1847, at the age of twenty-eight, the Viennese obstetrician Ignac Semmelweis famously deduced that, by not washing their hands consistently or well enough, doctors were themselves to blame for childbed fever. Childbed fever, also known as puerperal fever, was the leading cause of maternal death in childbirth in the era before antibiotics (and before the recognition that germs are the agents of infectious disease). It is a bacterial infection - most commonly caused by Streptococcus, the same bacteria that causes strep throat - that ascends through the vagina to the uterus after childbirth. Out of three thousand mothers who delivered babies at the hospital where Semmelweis worked, six hundred or more died of the disease each year - a horrifying 20 percent maternal death rate. Of mothers delivering at home, only 1 percent died.
Semmelweis concluded that doctors themselves were carrying the disease between patients, and he mandated that every doctor and nurse on his ward scrub with a nail brush and chlorine between patients. The puerperal death rate immediately fell to 1 percent - incontrovertible proof, it would seem, that he was right. Yet elsewhere, doctors' practices did not change. Some colleagues were even offended by his claims; it was impossible to them that doctors could be killing their patients. Far from being hailed, Semmelweis was ultimately dismissed from his job.
Semmelweis's story has come down to us as Exhibit A in the case for the obstinacy and blindness of physicians. But the story was more complicated. The trouble was partly that nineteenth-century physicians faced multiple, seemingly equally powerful explanations for puerperal fever. There was, for example, a strong belief that miasmas of the air in hospitals were the cause. And Semmelweis strangely refused to either publish an explanation of the logic behind his theory or prove it with a convincing experiment in animals. Instead, he took the calls for proof as a personal insult and attacked his detractors viciously.
"You, Herr Professor, have been a partner in this massacre," he wrote to one University of Vienna obstetrician who questioned his theory. To a colleague in Wurzburg he wrote, "Should you, Herr Hofrath, without having disproved my doctrine, continue to teach your pupils [against it], I declare before God and the world that you are a murderer and the 'History of Childbed Fever' would not be unjust to you if it memorialized you as a medical Nero." His own staff turned against him. In Pest, where he relocated after losing his post in Vienna, he would stand next to the sink and berate anyone who forgot to scrub his or her hands. People began to purposely evade, sometimes even sabotage, his hand-washing regimen.
Semmelweis was a genius, but he was also a lunatic, and that made him a failed genius. It was another twenty years before Joseph Lister offered his clearer, more persuasive, and more respectful plea for antisepsis in surgery in the British medical journal Lancet.
One hundred and forty years of doctors' plagues later, however, you have to wonder whether what's needed to stop them is precisely a lunatic. Consider what Yokoe and Marino are up against. No part of human skin is spared from bacteria. Bacterial counts on the hands range from five thousand to five million colony-forming units per square centimeter. The hair, underarms, and groin harbor greater concentrations. On the hands, deep skin crevices trap 10 to 20 percent of the flora, making removal difficult, even with scrubbing, and sterilization impossible. The worst place is under the fingernails. Hence the recent CDC guidelines requiring hospital personnel to keep their nails trimmed to less than a quarter of an inch and to remove artificial nails.
Plain soaps do, at best, a middling job of disinfecting. Their detergents remove loose dirt and grime, but fifteen seconds of washing reduces bacterial counts by only about an order of magnitude. Semmelweis recognized that ordinary soap was not enough and used a chlorine solution to achieve disinfection. Today's antibacterial soaps contain chemicals such as chlorhexidine to disrupt microbial membranes and proteins. Even with the right soap, however, proper hand washing requires a strict procedure. First, you must remove your watch, rings, and other jewelry (which are notorious for trapping bacteria). Next, you wet your hands in warm tap water. Dispense the soap and lather all surfaces, including the lower one-third of the arms, for the full duration recommended by the manufacturer (usually fifteen to thirty seconds). Rinse off for thirty full seconds. Dry completely with a clean, disposable towel. Then use the towel to turn the tap of. Repeat after any new contact with a patient.
Almost no one adheres to this procedure. It seems impossible. On morning rounds, our residents check in on twenty patients in an hour. The nurses in our intensive care units typically have a similar number of contacts with patients requiring hand washing in between. Even if you get the whole cleansing process down to a minute per patient, that's still a third of staff time spent just washing hands. Such frequent hand washing can also irritate the skin, which can produce a dermatitis, which itself increases bacterial counts.
Less irritating than soap, alcohol rinses and gels have been in use in Europe for almost two decades but for some reason only recently caught on in the United States. They take far less time to use - only about fifteen seconds or so to rub a gel over the hands and fingers and let it air-dry. Dispensers can be put at the bedside more easily than a sink. And at alcohol concentrations of 50 to 95 percent, they are more effective at killing organisms, too. (Interestingly, pure alcohol is not as effective - at least some water is required to denature microbial proteins.)
Still, it took Yokoe over a year to get our staff to accept the 60 percent alcohol gel we have recently adopted. Its introduction was first blocked because of the staff's fears that it would produce noxious building air. (It didn't.) Next came worries that, despite evidence to the contrary, it would be more irritating to the skin. So a product with aloe was brought in.
People complained about the smell. So the aloe was taken out. Then some of the nursing staff refused to use the gel after rumors spread that it would reduce fertility. The rumors died only after the infection-control unit circulated evidence that the alcohol is not systemically absorbed and a hospital fertility specialist endorsed the use of the gel.
With the gel finally in wide use, the compliance rates for proper hand hygiene improved substantially: from around 40 percent to 70 percent. But - and this is the troubling finding - hospital infection rates did not drop one iota. Our 70 percent compliance just wasn't good enough. If 30 percent of the time people didn't wash their hands, that still left plenty of opportunity to keep transmitting infections. Indeed, the rates of resistant Staphylococcus and Enterococcus infections continued to rise. Yokoe receives the daily tabulations. I checked with her one day not long ago, and sixty-three of our seven hundred hospital patients were colonized or infected with MRSA (the shorthand for methicillin-resistant Staphylococcus aureus) and another twenty-two had acquired VRE (vancomycin-resistant Enterococcus) - unfortunately, typical rates of infection for American hospitals.
Rising infection rates from superresistant bacteria have become the norm around the world. The first outbreak of VRE did not occur until 1988, when a renal dialysis unit in England became infested. By 1990, the bacteria had been carried abroad, and four in one thousand American ICU patients had become infected. By 1997, a stunning 23 percent of ICU patients were infected. When the virus for SARS - severe acute respiratory syndrome - appeared in China in 2003 and spread within weeks to almost ten thousand people in two dozen countries across the world (10 percent of whom were killed), the primary vector for transmission was the hands of health care workers. What will happen if (or rather, when) an even more dangerous organism appears - avian flu, say, or a new, more virulent bacteria? "It will be a disaster," Yokoe says.