SAN DIEGO – Researchers found “no compelling evidence” that carbapenem-resistant enterobacteriaceae were transmitted to Veterans Affairs patients during more than 55,000 endoscopic retrograde cholangiopancreatography (ERCP) and ultrasonography (EUS) procedures, Dr. Russell Ryono said at an annual meeting on infectious diseases.
The few clusters of cases uncovered by the 5-year retrospective analysis were separated not only in time, but by culture-negative patients treated with the same duodenoscopes at the same facilities, said Dr. Ryono of the public health surveillance and research office at the Department of Veterans Affairs in Palo Alto, Calif. “Our findings do not provide evidence of CRE transmission related to ERCP or EUS in Veterans Affairs,” Dr. Ryono and his associates concluded.
©CDC/James Archer
Contaminated duodenoscopes made headlines across the country this year after they caused outbreaks of fatal CRE infections in Los Angeles County. The Food and Drug Administration later acknowledged that the “complex design of the devices makes it difficult to remove contaminants compared to other types of endoscopes,” and both the Centers for Disease Control and Prevention and FDA recommended surveillance and reprocessing practices to help keep the scopes from transmitting serious infections.
In response to these concerns, the VA mined its data warehouses for ERCP and EUS procedures and CRE isolates recovered between January 2010 and the end of February 2015. Investigators looked for patients who were culture positive for the same type of CRE, underwent ERCP/EUS at the same facility within 6 months of each other, and were treated with the same scope or with an unidentified scope. Within this group, researchers honed in on “pairs” – or clusters – of patients in which the second patient exposed to the scope was CRE negative before the procedure and CRE positive afterward.
The initial query yielded more than 55,600 procedures among 40,329 veterans at 38 VA centers, as well as nearly 5,000 CRE isolates, more than half of which were cultured from urine samples, said Dr. Ryono. However, only 81 ERCP/EUS patients had CRE cultured from any anatomical site at any time. Among them, 57 patients were CRE negative before their procedure but CRE positive afterward, Dr. Ryono said.
There were 10 pairs of culture-positive patients treated at four facilities, one of which did not track serial numbers of duodenoscopes, according to Dr. Ryono. At that facility, procedure dates for pairs were 68-143 days apart, he said. Procedure dates for pairs at the other three facilities were spaced at least 82 days apart. Based on such extensive temporal spacing and the fact that the same scopes were used on culture-negative patients during intervening times, the investigators concluded that duodenoscopes were unlikely to have caused CRE infection or colonization.
Dr. Ryono noted several study limitations, however. Not only were CRE isolates unavailable for epidemiologic testing, but researchers also could not determine the extent to which facilities had implemented the 2010 guidelines for CLSI breakpoints. “Certainly, those facilities that have implemented those guidelines are more likely to catch CRE,” he said. Also, VA does not routinely screen patients for CRE before they undergo ERCP or EUS, “so it is very possible that some of our patients might have been colonized with CRE before the procedure, and we would not have been able to capture that,” he added. “Given the limitations of this review, the possibility that there was some transmission certainly cannot be completely excluded.”
Dr. Ryono reported these findings at the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.
The researchers declared no funding sources or conflicts of interest.