Duodenoscopes were the likely cause of the first nosocomial transmission of the mobile colistin resistance gene mcr-1 in the United States, researchers reported in Clinical Infectious Diseases.
“Contaminated endoscopes can transmit infectious microorganisms, with most transmission attributed to limitations in reprocessing or infection control,” Erica S. Shenoy, MD, PhD, infectious disease physician and associate chief of the infection control unit at Massachusetts General Hospital and assistant professor of medicine at Harvard Medical School, and colleagues wrote. “In 2014, however, an outbreak of New Delhi metallo-beta-lactamase-producing carbapenem-resistant Escherichia coli was caused by persistently contaminated duodenoscopes, and no such deficiencies were found.”
However, following similar outbreaks, Shenoy and colleagues said an FDA investigation “determined that the complex design of duodenoscopes, in particular their unique cantilevered elevator mechanism, impedes effective reprocessing.”
“We investigated the possible transmission of Klebsiella pneumoniae carrying mcr-1 via duodenoscope and report the first documented health care transmission of mcr-1-harboring bacteria in the United States,” Shenoy and colleagues wrote.
In their investigation, they screened high-risk groups, evaluated the duodenoscope in question and performed genome sequencing of isolated organisms.
According to the report, duodenoscope reprocessing was conducted using the manufacturer’s updated instructions for use. Following CDC guidelines, staff at Massachusetts General Hospital collected surveillance samples to assess for bacterial contamination, Shenoy and colleagues said. A third-party laboratory performed the culture-based analysis, according to the study.
The index patient had recurrent bacterial cholangitis and was admitted to the hospital with a fever in April 2017. On the first full day of admission, the patient underwent endoscopic retrograde cholangiopancreatography, according to the study. Because of the patient’s medical complexity, a clinician ordered colistin antimicrobial susceptibility testing in anticipation of future use, Shenoy and colleagues wrote. RT-PCR confirmed that K. pneumoniae isolates obtained from a bile culture were mcr-1-positive.
According to the authors, the second patient, who was admitted with walled-off pancreatic necrosis, was identified as a contact of the index patient via exposure to the same duodenoscope. K. pneumoniae isolates were found in two fluid specimens obtained from abdominal flank drains. Colistin antimicrobial susceptibility testing was performed and was positive for mcr-1.
The index patient reported travel to multiple Caribbean islands 4 months before admission. According to Shenoy and colleagues, “Caribbean travel has also been “reported among other individuals in the United States from whom bacteria harboring mcr-1 have been isolated.” They said the second patient was not recently hospitalized and did not have documented international travel. Additionally, the patient had no other shared exposures with the index patient beyond an endoscopic retrograde cholangiopancreatography performed with the same duodenoscope.
Investigation of the duodenoscope and cultured samples from the biopsy channel flush/brush and tip flush/brush specimens revealed Escherichia coli and K. pneumoniae isolates. K. pneumoniae isolates were negative for mcr-1. During an evaluation, however, the manufacturer “identified an area at the distal tip where adhesive had peeled off; after disassembly, foreign material was detected on the interior of the distal case and at the distal tip of the duodenoscope body,” Shenoy and colleagues wrote. They said such damage raises the risk for contamination.
Shenoy and colleagues concluded that transmission in this case “likely occurred via duodenoscope despite no identifiable breaches in reprocessing or infection control practices.”
They urged improved clinical laboratory capacity for colistin susceptibility testing and highlighted the need for an FDA-cleared test for the reliable detection of colistin resistance.
“Renewed focus on duodenoscope design, including an emphasis on disposable components, is needed,” they wrote. “Facilities should maintain heightened awareness of the risk of transmission through duodenoscopes, with procedures and processes to ensure adherence to reprocessing guidelines, vigilance for clusters of infections that may represent transmission, and continued discussions between clinicians and patients evaluating the risk-benefit ratio between these often lifesaving procedures and the ongoing risk of duodenoscope-associated infections.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.