In hospitals around the world, the snakelike duodenoscope is regarded as an indispensable tool for diagnosing and treating diseases of the pancreas and bile ducts.
But these fiber-optic devices have a remarkable drawback: Although they are inserted into the upper part of the small intestine through the mouth and constantly reused, they cannot be sterilized by the usual methods.
Instead, they are hand-scrubbed and then put through dishwasher-like machines that use chemicals to kill microorganisms. Even when cleaned as instructed, the devices may still retain bacteria that can be transmitted to patients.
As a result, duodenoscopes have sickened hundreds of patients in hospitals in the United States and Europe. Recent testing now suggests regulators severely underestimated the risks. Worse, the devices have been shown to be capable of transmitting antibiotic-resistant infections that are almost impossible to cure.
Alarmed medical experts are urging the Food and Drug Administration to force the manufacturers to develop scopes that can be properly sterilized — or to take all duodenoscopes off the market.
“The infection data are overwhelming and irrefutable, and the need is urgent,” William A. Rutala, the director of the statewide program for infection control and epidemiology at the University of North Carolina, said in an email.
Recent tests performed by the manufacturers at the demand of the F.D.A. found that one in 20 duodenoscopes retained disease-causing microbes like E. coli even after proper cleaning.
The agency had expected that fewer than one in 200 would retain bacteria after cleaning. Dr. David Jay Weber, medical director of the statewide program at U.N.C., said the finding was “astounding,” and called on the F.D.A. to set a deadline for manufacturers to fix the problem.
“Would you go on an airplane if the pilot said, ‘By the way, there is a 5 percent chance the engines will fail’?” Dr. Weber said. “Would you go in a car if the manufacturer said, ‘There are airbags, but 5 percent of the time they won’t deploy’?”
Dr. Jeff Shuren, the director of the F.D.A.’s Center for Devices and Radiological Health, suggested the agency may take additional regulatory action. “Improvements are necessary,” he said in a statement in April. No action has yet been taken, however.
Duodenoscopes are long, flexible tubes with a fiber-optic camera at one end. The tube is inserted through the patient’s mouth and stomach, then into the first part of the small intestine, called the duodenum.
The procedure, called endoscopic retrograde cholangiopancreatography, is used to diagnose and treat diseases of the pancreas, bile duct and gallbladder, such as life-threatening jaundice, tumors, blocked bile ducts and stones. More than half a million such procedures are performed each year in the United States.
The alternative is open surgery, which carries its own risks, said Dr. Bret Petersen, a gastroenterologist at Mayo Clinic in Rochester, Minn. “Taking a gallstone out surgically would be almost unheard of today,” he said.
But the inability to properly clean the instrument between patients has proved to be its “Achilles heel,” he added. The devices cannot be exposed to high heat to be sterilized, as many instruments are.
It is difficult to clean the narrow inner tubing by hand, and duodenoscopes, unlike other endoscopes, have a movable elevator-like mechanism at the tip that can be manipulated to adjust the position of surgical instruments.
The mechanism makes the scope more versatile, but also more difficult to clean, as it contains microscopic crevices where bodily fluids and bacteria can lodge.
Olympus Medical Systems Corporation, Pentax of America and Fujifilm Medical Systems USA manufacture most of the duodenoscopes in use in the United States, with the lion’s share made by Olympus. Until recent hospital outbreaks, the F.D.A. had never asked to review manufacturers’ data about cleaning the complex instruments.
The agency allows many medical devices onto the market without subjecting them to the kind of safety and effectiveness testing required for new drugs if the devices are deemed “substantially equivalent” to a medical device already on the market. It is the manufacturer’s responsibility to make sure the new device works properly — and that it can be properly cleaned between uses.
The manufacturers claim that as long as health facilities clean and disinfect the devices according to the instructions — a complicated process that can involve more than 100 steps, including visual inspections to check that no “soil or debris is visible” after cleaning — duodenoscopes are safe for patients.
The instructions also say devices should be returned to the manufacturer once a year for service and maintenance.
Since 2012, however, hundreds of patients in the United States and Europe have been infected in dozens of outbreaks linked to contaminated duodenoscopes. Among the infectious agents is carbapenem-resistant Enterobacteriaceae, bacteria that do not respond to a powerful class of antibiotics. The infection has a 50 percent mortality rate.
More than 30 patients in Seattle were infected with resistant strains of bacteria such as C.R.E. by duodenoscopes between 2012 and 2014, and 11 died, though many were already critically ill. Dozens of patients at a Park Ridge, Ill., hospital were infected with C.R.E. in 2013.
In 2015, two patients died and five were sickened after being infected with C.R.E. during procedures involving duodenoscopes at the Ronald Reagan U.C.L.A. Medical Center in Los Angeles.
Recently, doctors in Boston reported the first known transmission of a microorganism resistant to colistin, a last-resort antibiotic, through a duodenoscope that had been cleaned according to the manufacturer’s guidelines and F.D.A. recommendations.
When the scope was sent back to the manufacturer and taken apart, an internal defect was discovered that left the dangerous bacteria clinging to the instrument. The manufacturer, Pentax, recalled the defective devices last year.
“There is really no way we could have been able to pick up on these internal defects — that’s one of the main takeaways of this story,” said Dr. Erica S. Shenoy, the associate chief of infection control at Massachusetts General Hospital.
An F.D.A. advisory panel called for sterilization of duodenoscopes four years ago, when the outbreaks first came to light. Today, steam heat — the gold standard for cleaning and sterilization — can still damage the scopes, creating cracks where bacteria can lodge and necessitating more frequent replacements.
In February 2015, the F.D.A. asked manufacturers to analyze the contamination rates of their devices. But so far, manufacturers have only completed about 60 percent of the required sampling. One of the smaller companies has only completed 15 percent of the required tests.
The flurry of infection outbreaks puts patients, hospitals and health care providers in a quandary.
Modern medicine relies extensively on duodenoscopes and other flexible tubular “scopes” with cameras at the tips — including bronchoscopes to check the lungs, and colonoscopes to screen for colon cancer — to diagnose and treat diseases without surgery.
Alternatives to scoping are limited and include substitute medical tests and procedures, like stool tests that screen for colon cancer in lieu of colonoscopies. (Scopes used for colon cancer screening are considered much less risky, however, since they are used in a part of the body already teeming with bacteria.)
New low-temperature sterilization technologies may make it possible to disinfect scopes more effectively. And it is possible to manufacture disposable scopes that could be discarded after a single use.
Single-use bronchoscopes already are making their way to market, although they are not expected to replace reusable scopes. But there is no disposable duodenoscope.
The rising prevalence of superbugs — life-threatening germs that are resistant to powerful antibiotics — has heightened the sense of urgency.
“As long as organisms were susceptible to antibiotics, there really wasn’t a problem, because even if the scopes were transmitting bacteria, you give patients antibiotics prophylactically before and after procedures, and you take care of it,” said Larry Muscarella, a health care consultant who scours medical device reports submitted to the F.D.A. and has often been the first to identify infection risks.
But prophylactic antibiotics no longer guarantee protection. A rise in antibiotic-resistant infections worldwide is nearing a crisis point: The persistent misuse and overuse of antibiotics in people, plants and farm animals has led to the proliferation of bacteria that resist treatment to most available antibiotics.
The World Health Organization has called the growth in antibiotic-resistant disease one of the most significant threats to global health. The design of duodenoscopes makes them particularly susceptible to harboring these and other bacteria.
But the risk to any given patient is small, and duodenoscopes are not signficant factors in the rise of drug-resistant bacteria, said Dr. Alexander J. Kallen, an epidemiologist at the Centers for Disease Control and Prevention.
“It’s more of a public health concern than a concern for the individual patient,” he said. “The majority of people who get exposed to a scope contaminated with bacteria don’t suffer an adverse consequence.”
“For most patients, it’s a risk they should absolutely be aware of,” Dr. Kallen added. “But in most situations the benefits of the procedure probably outweigh the risks of an adverse event.”
The controversy has raised concerns about the safety of other reusable, flexible “scopes,” all of which have long, closed channels that are difficult to clean, let alone sterilize.
The F.D.A. warned health care providers in 2015 that bronchoscopes, which are used to examine the lungs, had been linked to more than 100 infections and might remain contaminated even after proper cleaning.
Late last year, researchers inspected two dozen bronchoscopes that had been cleaned and disinfected at three medical centers, and found that all retained “residual contamination” after the cleaning process, including pathogens like mold and E. coli.
All 24 bronchoscopes had irregularities apparent to the naked eye, including residues, retained fluid, scratches and other damage. An accompanying editorial said the results were alarming, and that the pulmonology community had “buried its head in the sand regarding this issue.”
In January, researchers at the University of Pittsburgh reported on a cluster of intensive care unit patients whose drug-resistant infections were all traced back to a single bronchoscope.
Ambu, a Danish company, is already marketing a disposable bronchoscope, officials said. The company also is testing a disposable colonoscope. It anticipates having additional endoscopes — including a disposable duodenoscope — on the market in the United States by 2020.
Though many hospitals in the United States have purchased single-use bronchoscopes, Ambu’s former chief executive, Lars Mercher, said the company encountered resistance to disposables when the product was launched.
“It was hard to even get acceptance for the idea that there was contamination in the hospital,” he said.