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Pseudomonas aeruginosa and Enterobacteriaceae bacteremia after biliary endoscopy: an outbreak investigation using DNA
M J Struelens1, F Rost, A Deplano
1Department of Microbiology, Hôpital Erasme, Université Libre de Bruxelles, Belgium.
Purpose:
An outbreak of gram-negative bacteremia in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) was investigated to determine the sources of infection and to control transmission.
Patients, Methods, And Results:
The incidence of post-ERCP bacteremia increased from 1.6% (60 of 3,696) procedures to 3.6% (53 of 1,454) procedures (relative risk 2.3, p < 0.0001) after endoscopes were processed in a new automated disinfector. Bacteremia involved nine species of Pseudomonas and Enterobacteriaceae, which were also isolated from processed endoscopes. Seven epidemic strains with highly related genomic macrorestriction profiles each infected 2 or more patients, accounting for 29 (55%) episodes of post-ERCP bacteremia. Strains recovered from endoscopes and from the disinfector were associated with 22 (42%) and 5 (9%) bacteremic episodes respectively. Effective endoscope disinfection was achieved by cleansing and disinfection of a blind channel not processed in the disinfector, additional isopropanol-air flush of all channels, and auto-disinfection of the disinfector. In the following period, the incidence of post-ERCP bacteremia returned to the pre-epidemic rate (1.7%, p = 0.0001).
Conclusion:
Bacterial genome fingerprinting by macrorestriction analysis enabled delineation of a multi-strain outbreak of post-ERCP bacteremia. Cross-contamination, and to a lesser extent, common-source contamination, appeared related to inadequate disinfection of endoscopes processed in an automated disinfector.
Insights
An outbreak of gram-negative bacteremia after endoscopic retrograde cholangiopancreatography (ERCP) was linked to inadequate endoscope disinfection. Improved cleaning protocols successfully reduced post-ERCP bacteremia rates, preventing further patient infections.
Area of Science:
- Infectious Diseases
- Gastroenterology
- Microbiology
Background:
- An increase in gram-negative bacteremia following endoscopic retrograde cholangiopancreatography (ERCP) procedures was observed.
- This rise in post-ERCP bacteremia coincided with the introduction of a new automated endoscope reprocessor.
Purpose of the Study:
- To investigate the sources of infection during an outbreak of gram-negative bacteremia in patients undergoing ERCP.
- To identify the causes of transmission and implement control measures.
Main Methods:
- Macrorestriction analysis of bacterial DNA was used to identify epidemic strains.
- Cultures were taken from processed endoscopes and the automated disinfector to identify sources of contamination.
- Changes in endoscope disinfection protocols were implemented, including manual cleaning of a blind channel, isopropanol-air flushing, and automated disinfection cycles.
Main Results:
- The incidence of post-ERCP bacteremia significantly increased from 1.6% to 3.6% after the new automated disinfector was implemented.
- Identical bacterial strains, including Pseudomonas and Enterobacteriaceae, were isolated from patients, endoscopes, and the disinfector.
- Seven epidemic strains were identified, accounting for 55% of bacteremia cases, with contamination linked to endoscopes (42%) and the disinfector (9%).
- Following the revised disinfection protocol, bacteremia rates returned to the baseline of 1.7%.
Conclusions:
- Inadequate disinfection of endoscopes processed in an automated system led to cross-contamination and common-source outbreaks of post-ERCP bacteremia.
- Bacterial genome fingerprinting was crucial in identifying the multi-strain outbreak and its sources.
- Implementing enhanced endoscope reprocessing protocols effectively controlled the spread of infection.