The Food and Drug Administration took 17 months to notify doctors and the public of “superbug” infection dangers from certain scopes used in gastrointestinal procedures in hospitals, according to a report by Senate Democrats released Wednesday.

The document said that in Sept. 2013, the staff at a Seattle hospital had “traced a cluster of antibiotic-resistant infections to a medical device” called a duodenoscope, but that it wasn’t until early 2015 that the FDA sent out a public warning.

“The agency took no action to alert hospitals, doctors and the public to the risk” posed by the medical scopes, Senate investigators wrote.

The report was commissioned by Sen. Patty Murray of Washington, the top Democrat on the Senate Committee on Health, Education, Labor and Pensions. The concentration of cases in Seattle has made the issue a particular concern to Ms. Murray, aides to the senator said.

A spokesman for committee chairman Lamar Alexander (R., Tenn.) declined to comment on why Republican committee members didn’t participate in the investigation and report.

FDA officials said Wednesday that they would “carefully consider” the Senate report recommendation and that reducing bacterial infections “is a top priority for the agency.” In August 2015, the agency recommended more rigorous cleaning steps for the devices.

The intricate scopes are snaked down the esophagus into the top of the small intestine for diagnostic and treatment procedures. These involve the liver, bile ducts and pancreas, and are often used in patients with cancer-related blockages. The FDA has estimated that more than 660,000 procedures are done annually with the device.

But difficulty in cleaning the scopes between patients has led to the hospital infection outbreaks. Virginia Mason Hospital and Medical Center in Seattle was one hospital that experienced an outbreak.

The report said that from 2012 through spring 2015, such scopes were linked to at least 25 different incidents of drug-resistant infections that sickened 250 patients world-wide.

“Patients should be able to trust that the devices they need for treatment are safe and effective,” said Sen. Murray, who instituted the investigation in early 2015. “Unfortunately, this investigation makes clear that current policies for monitoring medical device safety put patients at risk and, in this case, allowed tragedies to occur that could have, and should have, been prevented.”

Click for more from The Wall Street Journal.