Scope disinfection failure suspected in superbug cluster, leads UPMC to alter methods
A superbug lurking in scopes that examine the gastrointestinal tract infected a cluster of patients at UPMC Presbyterian, prompting the health care giant to change the way workers disinfect the widely used instruments, officials said Monday.
UPMC started investigating in November 2012 when several patients tested positive for a superbug called CRE, or carbapenem-resistant enterobacteriaceae. Top health authorities call the bug “nightmare bacteria” because it can be deadly, and most antibiotics are ineffective against it. None of the patients at UPMC died as a direct result of the infection, officials said.
Molecular testing matched cultures from 18 patients to the same bug found in a reusable scope that is typically inserted in the mouth and moved down the throat into the body. Only half of the patients carrying the superbug had undergone a gastrointestinal procedure, but it was enough for infection control specialists to suspect disinfection of the scope had failed, said Dr. Carlene Muto, director of infection prevention at UPMC Presbyterian.
Doctors could not establish with certainty if the scopes caused the infections because people can acquire the superbug from a variety of sources.
“You can't even prove causality that they got it from the scope. All we would know is that it was after the scope procedure, so it was a possibility,” said Muto, who gave a presentation on the topic last week at a national meeting of infectious disease experts in Philadelphia.
UPMC learned that a new scope design prevented disinfectant from reaching all parts of the device. All UPMC hospitals stopped using the scopes during the investigation and adopted a new disinfection technique to replace a high-level disinfection.
Muto called for new guidelines to disinfect the scopes with a gas sterilization method that uses ethylene oxide. It is now used to clean all scopes used in gastrointestinal procedures across UPMC and has not led to new cases of CRE, Muto said.
“I feel comfortable now that we're doing all the right things and doing everything we can to prevent transmission of this and other bacteria,” said Tami Minnier, UPMC's chief quality officer.
No patients died as a direct result of the CRE infection, Muto said. Some had heart failure and other chronic conditions, she said.
“It's impossible to say whether that infection was a contributor,” Muto said.
The patients underwent a type of screening called endoscopic retrograde cholangiopancreatography, or ERCP. More than 11 million such procedures are performed every year in the United States.
Flexible scopes used for diagnosing problems in the gastrointestinal tract harbor germs because they have compartments that are difficult to clean, even with powerful disinfectants, experts said.
“The flexible scopes are the devil,” said Marcia Patrick, an infection prevention consultant and faculty member for the Association for Professionals in Infection Control and Epidemiology. “Clearly, we need more research into this and better products that can be cleaned that don't have those nooks and crannies that allow bacteria to be trapped and not be killed.”
A study published last year in the Journal of Infection Control found that three out of 20 flexible gastrointestinal endoscopes harbored an unacceptably high level of germs that could pose a risk to patients.
The Centers for Disease Control and Prevention last year issued a warning about CRE bacteria. The germs kill one in two patients who get bloodstream infections from them, the CDC said.
The bug has been especially problematic in the southeastern part of the United States, where cases rose five-fold in community hospitals from 2008 to 2012, according to researchers at Duke University Medical Center.
Luis Fábregas is Trib Total Media's medical editor. He can be reached at 412-320-7998 or firstname.lastname@example.org.