Olympus, the leading maker of the endoscopes linked to recent "superbug" outbreaks at hospitals around the United States, asked the Food and Drug Administration to water down guidelines on cleaning medical devices that the agency proposed four years ago.

The FDA published a draft of the new guidelines in May 2011; they have not been finalized. They would set nonbinding recommendations for manufacturers of many types of medical devices, including the complex, hard-to-clean instruments called duodenoscopes, which recently harbored deadly drug-resistant bacteria at UCLA Medical Center and other hospitals. The day after the UCLA outbreak came to light, the FDA warned that the instruments involved may be impossible to fully sanitize.

An outbreak occurred in a Philadelphia hospital in 2014. Olympus has a medical device unit in Bethlehem, Pa.

The proposed FDA guidelines were intended to help medical-device makers prove that their cleaning methods were effective, and that instructions to the hospital staff would be adequate. Dozens of companies, individuals, and medical societies offered comments on the proposal, part of the normal wrangling over bureaucratic language.

In Olympus' comments, the company suggested that it should not be solely responsible for ensuring that the method of sanitizing scopes was effective. Instead, Olympus wanted a separate group of companies that make the equipment used to clean its devices to share that responsibility. Olympus and other scope manufacturers would have to show only that their products were compatible with the cleaning materials.

"For example, the endoscope manufacturer would identify the worst-case conditions" under which the instrument would need to be cleaned, according to Olympus' comment letter. Then the companies that make the cleaning systems would test how effective the process is "on behalf of the endoscope manufacturer." The scope maker "would perform the material durability and compatibility analysis" to see how the scope withstood repeated cleanings.

Olympus is the leading maker of duodenoscopes, which are threaded through the mouth and the gastrointestinal tract to reach tiny ducts in the pancreas or gallbladder. Cleaning such devices has been a challenge for hospitals for years.

If the FDA adopts the change in its final guidelines, that could shift some of the blame for scopes that spread deadly pathogens away from device manufacturers and onto the companies that make the cleaning systems. Olympus is facing lawsuits in California and Washington state from patients or families who say patients were harmed when its devices transmitted drug-resistant infections. At least 13 people have died and dozens have been sickened in outbreaks in the two states that have come to light since January. Other factors may have caused or contributed to the deaths, since patients who get duodenoscope procedures are often already ill.

Olympus spokesman Mark Miller did not reply to messages asking about the company's 2011 comments on the FDA proposal. In an e-mail from March 4, he declined to comment on active legal matters, but said that a half-million procedures using duodenoscopes are performed in the U.S. each year, "and while any complication affecting a patient's health is a serious matter, the reported incidence of infections is extremely low."

The FDA is "working diligently to get the final reprocessing guidance out as soon as possible," spokeswoman Leslie Wooldridge wrote in an e-mail, without specifying a deadline.