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Duodenoscopes—Necessary But Dangerous?

They’re Hard to Clean, Putting Patients at Risk

The snakelike duodenoscope is an indispensable tool, but the fiber-optic device has a drawback: The inability to properly clean the instrument between patients. The devices cannot be exposed to high heat to be sterilized, as many instruments are, but it’s difficult to clean the inner tubing by hand. 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 it has microscopic crevices where bodily fluids and bacteria can lodge.

As a result, duodenoscopes have sickened hundreds of hospital patients. Alarmed medical experts are urging the Food and Drug Administration (FDA) to force manufacturers to develop scopes that can be properly sterilized—or to take all duodenoscopes off the market. Recent tests performed by manufacturers at the demand of the FDA found that one in 20 duodenoscopes retained disease-causing microbes like Escherichia 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 the University of North Carolina, said the finding was “astounding,” and called on the FDA to set a deadline for manufacturers to fix the problem.

Dr. Jeff Shuren, director of the FDA’s Center for Devices and Radiological Health, suggested that the agency may take additional regulatory action, but no action has yet been taken. Since February 2015, when the FDA asked manufacturers to analyze the contamination rates of their devices, manufacturers have only completed about 60% of the required sampling.

Olympus Medical Systems Corporation, Pentax of America, and Fujifilm Medical Systems USA manufacture most of the duodenoscopes in use in the United States. Until recent hospital outbreaks, the FDA had never asked to review manufacturers’ data about cleaning.

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 that devices should be returned to the manufacturer once a year for maintenance.

Recently, doctors in Boston reported the first known transmission of a microorganism that is resistant to colistin, a last-resort antibiotic, through a duodenoscope that had been cleaned according to manufacturer guidelines and FDA recommendations. When the scope was returned to the manufacturer, an internal defect was discovered that left the dangerous bacteria clinging to the instrument. The manufacturer, Pentax, recalled the defective devices last year.

Steam heat—the gold standard for cleaning and sterilization—can damage the scopes, creating cracks where bacteria can lodge and necessitating more frequent replacements. New low-temperature sterilization technologies might make it possible to disinfect scopes more effectively. And it is possible to manufacture disposable single-use scopes. Ambu, a Danish company, anticipates having a disposable duodenoscope on the market by 2020.

The rise of superbugs has heightened the sense of urgency. Prophylactic antibiotics no longer guarantee protection. But the risk to any given patient is small, and duodenoscopes are not significant factors in the rise of drug-resistant bacteria, says Dr. Alexander J. Kallen, an epidemiologist at the Centers for Disease Control and Prevention. “[I]n most situations the benefits of the procedure probably outweigh the risks of an adverse event.”

Source: New York Times, August 6, 2019

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