A new report from a public health department in Seattle that examines Seattle’s 10-month outbreak of a superbug in 2013 indicates that despite efforts to make duodenoscopes–the medical devices responsible for the transmission–risk-free, they still pose a risk to patients at hospitals nationwide, the Los Angeles Times reports. Los Angeles suffered an outbreak last year that was reported in early 2015.

The Seattle report’s lead author, Kristen Wendorf stated, “We suspect endoscope-associated transmission of bacteria is more common than recognized and not adequately prevented by current reprocessing guidelines.” The report found it “especially disturbing” that the Seattle hospital involved in the outbreak had carefully cleaned the scopes per the manufacturer’s instructions but the outbreak happened anyway.

Only last week, Olympus Corp., the primary manufacturer of the duodenoscopes used in the superbug outbreaks at L.A’s Ronald Reagan UCLA Medical Center, Cedars Sinai Medical Center, and Virginia Mason Medical Center in Seattle, sent an urgent update to U.S. hospitals to alert them that the manufacturer’s instructions for cleaning duodenoscopes needed to be augmented by other cleaning efforts, according to the Times.

32 patients at Virginia Mason contracted CRE; eleven died. The current procedure at the hospital involves cleaning the scopes, then shelving them for 48 hours so the hospital can run culture tests to check for latent bacteria. Even after that protocol, 3% of the scopes are still unsafe.

At UCLA, ERCP, or endoscopic retrograde cholangiopancreatography, which used the duodenoscopes, introduced CRE, or carbapenem-resistant Enterobacteriaceae, into at least two patients at UCLA’s Ronald Reagan Medical Center who died as a result. Five other patients were also exposed to the superbug; 180 more may have been exposed.

The Times reported on Monday that U.S. Rep. Ted Lieu (D-Los Angeles) sent a letter on Friday to Pentax Medical, which also makes duodenoscopes, to ask what steps it was taking vis-à-vis cleaning its instruments. Pentax scopes were used at Advocate Lutheran General Hospital north of Chicago, where over 40 patients contracted CRE in 2013. Lieu has previously asked Congress to investigate the outbreak.