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In late February, 2015 the University of California, Los Angeles (UCLA) Medical Center reported a cluster of carbapenem-resistant Enterobacteriaceae (CRE) cases in patients who underwent endoscopic retrograde cholangiopancreatography, or ERCP, between October 3, 2014 and January 28, 2015. Duodenoscopes, a complex type of endoscope, are used to perform ERCP. Of the 179 patients who had procedures during that time, at least nine contracted CRE and two died from infection. Subsequent evaluation of endoscope reprocessing procedures revealed that they were reprocessed according to manufacturer’s recommendations and normal procedures, using a popular, FDA-approved high-level disinfectant.
Molecular fingerprinting of the CRE isolates from the infected patients showed them to be clonal, meaning they were very likely to have originated from the same source. The only thing that all patients had in common was ERCP performed with two particular, serial number-tracked duodenoscopes.
UCLA Medical Center staff attempted to use an interim CDC protocol to isolate viable CRE from the endoscopes in question, but none was detected. Nevertheless, the molecular evidence demonstrates without doubt that the two endoscopes were the cause of the infections and deaths. Microchem Laboratory suspects the CRE may have been inhibited from growth by residual OPA present on the endoscopes. For that reason, Microchem incorporates neutralizing agents into its sampling and transfer medium and tests for neutralization at the time of sampling.
CRE is noteworthy as the causative organism in that it happens to be rare, deadly, and easily isolated from the fecal flora expected to contaminate endoscopes. It is also not resistant to disinfectants, and certainly not high-level disinfectants, such as OPA. The presence of CRE on properly processed endoscopes, coupled with anecdotal evidence from endoscopic surgeons and microbiologists who have sampled processed endoscopes, suggests that they may be frequently contaminated after reprocessing, just not with such pathogenic, detectable bacteria.
It is worth noting that more than 500,000 ERCPs are performed each year in the United States to clear bile ducts, remove cancers, etc., so the net benefit of the procedure is overwhelming despite existing infection risks.