(Reuters) - An unnamed hospital in Oklahoma used contaminated gastroscopes in procedures performed on nearly a thousand patients in recent months, device maker Pentax Medical told U.S. regulators last month, putting the patients at risk of exposure to bacteria that can cause infections.

In a July 22 report here&pc=FDS that only recently became public and was reviewed by Reuters, Pentax told the Food and Drug Administration that a hospital used up to four gastroscopes contaminated with bacteria in 998 procedures performed sometime last year through June 2019, when the problem was discovered. Pentax, a unit of Tokyo-based Hoya Corp, said it was not aware of any patient infections thus far.

Gastroscopes are inserted in the mouth and used to examine the stomach, conduct biopsies and perform other procedures.

The FDA redacts the names of hospitals from device injury reports before releasing them publicly. “Per FDA regulation, we are not permitted to disclose the facility identity publicly,” agency spokeswoman Alison Hunt said.

Neither Pentax nor the Oklahoma State Department of Health would name the hospital involved.

In a statement to Reuters, Pentax described the incident as a “failure by the facility reprocessing personnel to completely follow” the company’s cleaning instructions for gastroscopes.

The company said the “hospital has notified all potentially affected patients of their options for post-exposure medical screening.”

The FDA echoed Pentax’s assessment and said regulators “have determined that the manufacturer’s reprocessing instructions were not followed.” The agency said it is continuing to discuss the incident with Pentax and the hospital to learn more details.

Gastroscopes, like other endoscopes, are brushed and washed with disinfectants in preparation for the next patient. Despite those efforts, contamination can persist and patients can be exposed to drug-resistant bacteria and develop infections that are difficult or even impossible to treat.

They are not required to be sterilized, a process that for many manufacturers would require design changes to enable complex scopes to withstand gas or chemicals.

DESIGN HINDERS CLEANING

U.S. Senator Patty Murray of Washington state, who led a Senate investigation into duodenoscope infections following an outbreak at a Seattle hospital several years ago, expressed concern about the persistent lapses in patient safety related to endoscopy despite years of scrutiny by regulators and lawmakers.

Duodenoscopes are another type of endoscope.

Murray told Reuters that families “should be confident the medical equipment they rely on for critical procedures is safe. But I’m still very concerned about the risks here and I’m going to keep pushing for more transparency, more accountability and stronger protections for patients.”

Researchers say the intricate design of many endoscopes, with narrow channels and tiny crevices, hinders cleaning and those problems are compounded when health workers skip steps or ignore basic protocols in a rush to get scopes ready for the next patient.

In a study published last year in the American Journal of Infection Control, 71% of reusable scopes deemed ready for use on patients tested positive for bacteria at three U.S. hospitals. The study found problems with gastroscopes, colonoscopes and bronchoscopes, among others.

“Scopes get highly contaminated every time they’re used,” said Cori Ofstead, the study’s author and an epidemiologist in St. Paul, Minnesota. In the latest incident involving gastroscopes, she said, “It appears the institution continued to use damaged scopes, and inadequate cleaning allowed potential pathogens to remain on the scopes.”

In its filing to the FDA, Pentax said the “forward water jet channel” was not properly cleaned on three of the gastroscopes and a “foreign liquid was evacuated from at least one of the devices upon flushing” that channel. After discovering the problem, the hospital took the scopes out of service and returned them to Pentax.

Some infection-control experts have urged manufacturers and regulators to move toward sterilization for scopes, which would be a step above the current U.S. requirement for high-level disinfection.

Some companies are selling single-use scopes as a safer alternative, but reusable devices continue to be used widely.

In 2015, the FDA ordered Pentax and two other scope manufacturers – Olympus Corp and Fujifilm Holdings Corp – to conduct surveillance studies after the spread of antibiotic-resistant “superbugs” at U.S. and European hospitals from contaminated duodenoscopes. Those gastrointestinal scopes are put down a patient’s throat to diagnose and treat problems such as gallstones, cancers and blockages in the bile duct.

In April, the FDA said 5.4% of duodenoscopes tested positive during those industry studies for “high concern” organisms such as E. coli, even after being disinfected. The FDA said that contaminated duodenoscopes were linked to three deaths last year and 45 reports of patient infection from October 2018 to March 31.

This week, FDA urged hospitals and device makers to adopt newer models of duodenoscopes that have disposable parts that can aid cleaning and reduce the risk of infection.

“We recognize that a full transition away from conventional duodenoscopes to innovative models will take time and immediate transition is not possible for all health care facilities due to cost and market availability,” Dr. Jeff Shuren, director of the FDA’s Center for Devices and Radiological Health, said in a statement Thursday.