A surprising ingredient — abdominal gas relief drops for infants — may be contributing to the contamination of medical scopes nationwide and putting more patients at risk of infection, according to a small but provocative study.
Researchers in Minnesota unexpectedly found cloudy, white fluid inside several colonoscopes and gastroscopes after they had been disinfected and deemed ready for use on the next patient.
Further analysis revealed the fluid contained simethicone, the main ingredient in over-the-counter anti-gas medications available at grocery stores and pharmacies. Doctors nationwide regularly inject drops of the liquid medication into gastrointestinal scopes during colonoscopies and other procedures to reduce bubbles inside the body that can impede visibility.
However, that routine practice may be helping bacteria grow inside a wide variety of scopes and making the bacteria hard to remove. The authors of the study, published in August in the American Journal of Infection Control, recommend that hospitals and doctors minimize the use of these products pending further research into their effect on patient safety.
No infections have been specifically linked to the drops thus far. The study only suggests that they could heighten the risk of contamination. "Finding residual fluid in scopes that should be dry would be troubling alone," said Cori Ofstead, the study's lead author. "The finding of fluid containing simethicone suggests we have more serious problems. It could explain why we are having more trouble getting these scopes clean."
Infant gas relief drops, which are available over the counter, contain sugars and thickeners to make the liquid solutions more palatable for babies. Ofstead said those ingredients "could provide the perfect habitat for the growth of bacteria" inside scopes.
The liquid drops also contain silicone, which doesn't dissolve in water and can't be removed using detergents or disinfectants. The researchers said that silicone could add another impenetrable coating to blood, tissue and other organic material trapped inside scopes. It can also foster the growth of biofilm, a slimy material that can protect bacteria and other microbes from being removed during cleaning.
Ofstead, an epidemiologist and chief executive of the medical research firm Ofstead & Associates in St. Paul, Minn., said these findings were "absolutely surprising" and that researchers stumbled upon them during a broader look at scope-cleaning techniques. The seven-month study was conducted with physicians and a surgery center affiliated with the University of Minnesota Health system.
Dr. Michael Shaw, a gastroenterologist and a co-author of the study, says halting the use of simethicone products would hinder doctors' ability to accurately treat patients with endoscopy. He's pursuing funding for larger studies at other endoscopy centers to determine the extent of the problem and possible alternatives.
"I don't want to see the public alarmed, but this study did raise a huge number of questions," says Shaw, an associate professor at the University of Minnesota Medical School.
Federal prosecutors, U.S. lawmakers and government regulators have been investigating a series of outbreaks of antibiotic-resistant "superbugs" across the country tied to a specific device known as a duodenoscope, which is used in about 700,000 procedures annually. Overall, as many as 350 patients at 41 medical centers worldwide were infected by or exposed to contaminated duodenoscopes from 2010 to 2015, according to the Food and Drug Administration.
Regulators and medical experts have said the duodenoscope's complex design at its tip can make it difficult to clean even when following the manufacturer's instructions. The infant gas relief drops are used occasionally with duodenoscopes, doctors say, and it's unclear what role, if any, those products might have had on patient infections.
This new study focused on more widely used colonoscopes and gastroscopes, which have simpler designs and tend to be easier to disinfect. The researchers found bacteria in some of the scopes that were analyzed, but they weren't the drug-resistant superbugs that can be deadly for patients.
The findings raise questions for the three largest manufacturers of gastrointestinal endoscopes and the doctors who use the devices to treat millions of patients annually.
Scope manufacturers are well aware that anti-gas products are used to reduce bubbles. Two companies — Pentax Medical and Fujifilm — have told healthcare providers that injecting these drops into endoscopes is not recommended because residue can build up and impede cleaning.